This will include a basic introduction to logic and logical fallacies.

2. Critical Thinking I: How to be a
Reasonable Person
Critical thinking is about reasoning clearly and effectively to achieve our goals. The
traditional goal in critical thinking courses is getting at the truth and avoiding falsehoods.
Our conception of critical thinking can be expanded to include other goals and
appropriate standards for achieving these. So, for instance, an architect isn’t concerned
with getting at the truth, but with good design. So, an architect will be concerned with
standards and methods appropriate to achieving good design. But even in this context,
it would be irrational for an architect to ignore truths about, say, the load bearing
properties of various building materials. Whatever our goals, getting at the truth about
many things will matter. So, truth oriented critical thinking in the context of inquiry is a
vital and indispensable foundation for reasoning effectively.
Biases and confusions about the nature of truth and reason are widespread. So, we are
going to start here by introducing the metaphysical and conceptual framework typically
presupposed in inquiry. We will also discuss the personal traits and social conditions
that are required for inquiry to proceed productively. In the next chapter we will get
acquainted with the methods and skills employed in reasoning clearly and effectively.
This will include a basic introduction to logic and logical fallacies.
Subjects and Objects
Let’s start with the modest metaphysical assumption that we all live on planet Earth.
This means we have a shared reality. One that is populated with various and sundry
objects (or better, containing stuff that can be divided in to objects in any number of
ways). This is the realm of objects, or the objective world. As embodied creatures, we
are among the objects populating the objective realm. But in addition to being objects
we are also subjects.
As subjects we have some experience of our shared reality, the objective realm. But,
our experience of the world is limited by our perspectives. Further our impressions and
beliefs are liable to be distorted by biases and assorted other intellectual bad habits. So,
one thing we can all recognize about being subjects is that our impressions, beliefs and
opinions are fallible. We are limited and imperfect in ways that make error quite
possible. That’s just life as a subject, having subjective impressions and beliefs means
being prone to error. Fortunately, we can always expand the basis of evidence we
reason from by sharing our impressions and beliefs with each other. And we can
improve the reliability of our reasoning by cultivating the intellectual habits that steer us
away from biased and distorted ways of thinking. This is the point of critical thinking.
Philosophers typically use the word “subjective” to refer to what is mind dependent. All
of your thoughts, feelings and beliefs exist in the subjective realm in this sense of the
word. But then your beliefs are about the objective world. When I believe I have
chocolate ice cream in the freezer, I’m representing a part of the objective world as
being a certain way. So, my belief while it exists in the subjective realm as a property of
me, a subject, is about the objective realm and it can accurately represent an aspect of
the objective world. In which case my belief is true. Or it can fail to fit the way things are,
say, if my son has finished the chocolate ice cream. In this case my belief is false.
So, your beliefs, are aspects of you, a subject, but they aim at representing things that
are going on in our shared reality, aspects of the objective realm. For your belief to be
true is just for your representation of how things are in the objective realm to fit or
correspond with what is actually going on in the objective realm. That is, your belief is
true when it represents some aspect of our shared reality the way it is.
Subjective realm includes whatever
depends on your mind as a subject
Objective realm includes all aspects of
our shared reality
All your thoughts, sense impressions,
feelings, beliefs, fears and hopes are
aspects of you as a subject.
The objective realm includes all the
things, states of affairs and ways things
are independent of you as a subject.
As subjects, it is generally good for us to have true beliefs and avoid false beliefs. When
we have true beliefs, we are more capable of acting effectively, achieving goals,
avoiding hazards, and generally having a good time. I suppose this is a value
statement, but not the sort of value statement anyone is likely to dispute. This much of
the value of having true beliefs comes along with being subjects who have needs and
goals in a world full of objects (and subjects) that can be helpful or harmful to us. So,
special cases aside, it’s good to have true beliefs.
Truth
We just claimed that for your belief to be true is for it to represent things as they are.
The basic idea here is that beliefs and claims are true when they correspond to how
things are in our shared reality. Ordinary declarative sentences say something about
how things are. What a declarative sentence says represents some aspect of reality.
So, take a few everyday examples:
• There is a spruce tree in Stuart’s front yard.
• Lake Washington is east of downtown Seattle
• Your keys are on the kitchen counter.
Each of these sentences represents some aspect of our shared reality as being a
certain way. The sentence is true if that part of the world is the way the sentence says it
is. Since truth is about correspondence with our shared reality, it concerns the objective
realm. Truth is objective.
Our society is currently riddled with some confusing ways of talking about truth. We
have become accustomed to talking about “my truth” or “your truth.” But if we stay
focused on our ordinary understanding of truth as correspondence to reality, we can
avoid confusions about truth being subjective or relative. Corresponding to our shared
reality is obviously what we mean when we count the belief that Lake Washington is
east of Seattle as true. For my belief or claim to be true is just for it to represent some
aspect of our shared reality as it is. What is true depends only on how things are
objectively in our shared reality. Beyond shaping what is true about my own mind, I
can’t make things true merely by willing, wishing or believing them.
Given this ordinary everyday understanding of truth, it should be clear the truth doesn’t
belong to anyone. Nobody gets to dictate, define or decide what is the case, except in
the very limited respect where a person decides what to do, how to think, or who to be.
As a subject, I have this much power to shape our shared reality and no more. There is
no “my truth” or “your truth.” The only way to make sense out of truth being subjective
would be to deny the existence of a shared reality. Truth could be subjective only if I live
in my own little world and you live in your own separate reality. This would be to reject
the very modest metaphysical assumptions we started this chapter with. I can’t prove
that we have a shared reality, but not having one sure sounds lonely.
When I believe something, I take it to be true. I suspect this is all most talk of “my truth”
or “your truth” amounts to, a confusing way of talking about what we believe. But this
kind of talk involves a rhetorical cheat in suggesting that my belief, which could well be
just plain false, is still somehow to be associated with what is true. Worse, talk of “my
truth” and “your truth” blurs the difference between the subjective and the objective.
Finally, before we leave the topic of truth, let’s consider the difference between these
two questions:
• What is it for a claim to be true?
• How do we determine that a claim is true?
It’s important to keep these two questions separate. Questions about how we know
whether something is true are epistemic questions. These questions are concerned with
how our minds relate to the world. But the question of what it is for something to be true
is not an epistemic issue. The truth of a claim is quite independent of how or whether
we know it to be true. There are many truths we don’t know and some of the things we
think we know just aren’t true. If you are not sure about this, consider these two claims:
• There is intelligent life on other planets.
• There is no intelligent life on other planets.
One of these claims is true. We can be sure of this on the basis of logic alone. Either
claim being false would make the other true. We don’t know which of these two claims
is true and yet one of them is true. Whichever of these claims is true, its being true
doesn’t depend on whether we know it to be true. There are many truths that will never
be known or believed by anyone, and appreciating this is enough to see that the truth of
a claim is not relative to belief, knowledge, proof, or any other epistemic notion.
So, what it takes for a claim to be true doesn’t depend on what we believe, or what we
think we know, (except in the special case of claims about what we believe). What it
takes for a claim to be true only depends on what on how things are in our shared
reality. Once we get clear on subjects, objects and truth, the answer to our first question
above is pretty clear. All it is for a claim to be true is for what it says to fit with how
things are. But, naturally most of us are more concerned with how we can determine
when the claims people make and the things we believe are true. This question is more
challenging. It’s also what critical thinking and epistemology are about. We we will get to
the issue of how to determine whether a claim is true or false in the next chapter when
we turn to the basic methods for evaluating reasons and evidence.
Rationality
For your beliefs to be rational, or reasonable (we’ll treat these terms as synonyms), is
just for them to be held on the basis of the best available reasons. To be reasonable, in
the literal sense of the word, is to be amenable to reason. That is, the reasonable
person is the person who forms or revises beliefs by yielding to the best reasons.
Good reasons are reasons that are truth-oriented. So, all it means for your belief to be
rational, or reasonable, is for it to be held for the most truth-oriented reasons available
to you. This much should make it clear why it is good to be rational. Being rational is
more likely to get you true beliefs and true beliefs are good because they help you act
effectively, achieve your goals, avoid hazards, and they give you a shared basis for
understanding and communicating with others.
[We should note that the words “rational” and “reasonable” can also refer to choosing or
acting in ways that aim at maximizing some goal or value Words are often ambiguous.
The way to be comfortable with ambiguity is to get clear on how words are being used
and to track the various usages. Talk of rational or reasonable belief (as opposed to
choice or action) can generally be understood as truth-oriented simply because to
believe something is to take it to be true].
Rationality is not a kind of human imposed authority over what is true or what we should
believe. The only thing that is authoritative concerning what we should believe is how
things are in our shared reality. Again, to believe something is to take it to be true. To
believe rationally is just to believe in a ways that target the truth well. To believe
irrationally is to aim badly at the truth. Rational belief isn’t guaranteed to hit the target of
truth. But irrational belief involves a kind of unforced error.
Talk of rationality, objectivity and truth have some difficult connotations in the minds of
many. These concepts often get associated with things like maleness, authority, power,
and now even “whiteness.” These difficult associations appear to be based on
antiquated stereotypes of one sort or another. But thinking based on stereotypes is
highly unreliable and perhaps we are in a position now to see how thinking in terms of
stereotypes misleads many of us concerning these fundamental concepts. To be
reasonable literally means to be amenable to good reasons (this especially includes the
good reasons of others who think differently). To be a reasonable or rational believer
involves a good measure of intellectual humility and a constant awareness of how easy
it is be misled in the pursuit of knowledge and understanding. So reasonable people are
careful and cautious thinkers. Good critical thinkers get well acquainted with lots of
logical fallacies, mistakes in reasoning, in order to avoid known pitfalls in thinking. The
rational believer doesn’t let ego and willfulness get in the way of her evaluation of claims
and reasons. The reasonable or rational believer doesn’t force things, but rather yields
to best reasons and evidence. I won’t delve into stock stereotypes here except to point
out that being amenable to other perspectives, intellectually humble and cautious, and
yielding to the better ideas don’t stereotypically characterize maleness, authority or
whiteness. But they do characterize reasonableness and rationality.
We started with two metaphysical assumptions here. Namely that we have a shared
reality and that we each have limited and fallible experience of that reality. To this we’ve
added a few definitional remarks about truth, rationality, reason, belief, subjectivity and
objectivity. And we’ve reasoned a bit on the basis of these assumptions and definitions.
In the definitional remarks I’ve tried to lay out standard philosophical usage clearly and
straightforwardly.
The reason it is good to understand truth, rationality etc. in the manner I’ve laid out here
is that it facilitates clearer communication and understanding of our diverse experiences
and diverse ways of thinking. This allows us to cooperatively improve our ways of
thinking and our limited grasp of what’s true. And as a result of this, we are empowered
to act more effectively, avoid hazards in our interactions, appreciate each other more
significantly, and enjoy things.
Some will be tempted to object to what I’ve laid out here on the grounds that people are
free to define things like truth and rationality as they please. In a sense, people are free
to do so. Nobody has the power to prevent it. All the other concepts we might be
tempted to attach to these words are out there and as a linguistic community of a couple
people or of a couple billion we could agree to name those concepts as we please. But
to insist on defining things as we like amounts to the privatization of language, with the
primary result of undermining our capacity to communicate with one another and
understand each other in the limited ways that are open to us. I am no fan of such
hyper-individualism. While we could quibble about how to define truth and rationality,
the only result of this would be to talk about something else instead. Something other
than how we stand as subjects to each other and our shared reality.
Philosophy as Inquiry
Philosophy is a branch of inquiry. Inquiry or investigation is the effort to figure something
out, to get at the truth of some matter. Fruitful inquiry that produces lasting knowledge
and understanding is typically a community affair. As individuals, all we have to work
with is our own individual point of view based on our limited experience and whatever
thought processes we are used to or comfortable with. In this predicament, an individual
has only new evidence to help check for errors. Worse, many of us are quite adept at
only noticing the evidence that supports what we already think, which precisely misses
all the evidence that might check for errors in our thinking. This is the problem is known
as confirmation bias. So, as individuals we are stuck with very limited evidence and little
significant error checking. But as a community of inquirers, we can pool our diverse
evidence and review our various thought processes. This is how inquiry has always
proceeded. The current understanding in an area of science or philosophy is the result
of a great many conversations, sometimes going back centuries or millennia, some in
person, some in print, some on YouTube.
Once a philosophical position is considered, we want to ask what arguments can be
advanced in support of or against that position. In order to get at the best reasons, it is
vital that our community of inquirers include people with diverse perspectives and
diverse ways of thinking. Otherwise, we are liable to miss important evidence, overlook
good reasons, or fail to find flaws in the arguments we do consider. A community of likeminded people will tend to share the same blind spots and hence ignore illuminating
alternative perspectives and neglect the error checking these can provide.
We then want to examine the quality of the arguments for and against a given position.
Evaluating flawed arguments often points the way towards other arguments and the
process of formulating, clarifying, and evaluating arguments continues.
This method of question and answer in which we recursively formulate, clarify, and
evaluate arguments is known as dialectic. Dialectic looks a lot like debate, but a big
difference lies in the respective goals of the two activities. The goal of a debate is to win
by persuading an audience that your position is right and your opponent’s is wrong.
Dialectic, on the other hand, is aimed at inquiry. The goal is to learn something new
about the issue under discussion. Unlike debate, in dialectic your sharpest critic is your
best friend. Critical evaluation of your ideas and arguments brings new evidence and
reasoning to light. The person you disagree with on a philosophical issue is often the
person you stand to learn the most from (and this doesn’t necessarily depend on which
of you is closer to the truth of the matter).
Dialectic is sometimes referred to as the Socratic Method after the famous originator of
this systematic style of inquiry. We will get introduced to some of Plato’s dialogues
chronicling the exploits of Socrates later. This will give you a good sense for how the
Socratic Method works. Then watch for how the Socratic Method is deployed throughout
the rest of the course.
The Fruits of Inquiry
We come to know what is true through inquiry. Sometimes this is as straightforward as
making some observations. I know that it is sunrise by looking out the window.
Sometimes inquiry is an involved process of formulating questions, identifying possible
answers, formulating arguments that bear on these and then critically evaluating the
arguments in light of whatever evidence we have to work with. The steps in this process
may be repeated or elaborated as needed depending on the complexity of the issues
raised.
Sometimes inquiry fails to yield definitive knowledge. Sometimes we don’t have the
evidence we need to settle an issue. And sometimes it is not so clear how to reason
well from the evidence we have. As we heard from Bertrand Russell last week,
philosophers often fail to uncover the truth of issues they inquire into. So, where inquiry
yields no definitive right answer, what’s the point of inquiry?
Inquiry bears many fruits even when it doesn’t yield final answers. Inquiry can help us:
• clarify our questions
• distinguish different if closely related issues
• identify the plausible answers
• rule out some wrong answers
• appreciate the implications of some possible answers for other related issues
• increase our understanding of issues by doing some or all of the above
As we will see throughout the course, philosophical inquiry often follows a dialectical
pattern where we propose a view, offer arguments for that view, critically evaluate the
arguments, learn from our mistakes, rinse and repeat. Inquiry proceeds incrementally
through a dialectical process of trial and error. As the Muslim philosopher, Alhazan, put
it (around 1025):
The seeker after the truth is not one who studies the writings of the ancients and,
following his natural disposition, puts his trust in them, but rather the one who
suspects his faith in them and questions what he gathers from them, the one who
submits to argument and demonstration, and not to the sayings of a human being
whose nature is fraught with all kinds of imperfection and deficiency. Thus, the
duty of the man who investigates the writings of scientists, if learning the truth is
his goal, is to make himself an enemy of all that he reads, and, applying his mind
to the core and margins of its content, attack it from every side. He should also
suspect himself as he performs his critical examination of it, so that he may avoid
falling into either prejudice or leniency
Notice in this rather militarized analogy that the discovery of truth happens when your
attack fails and you “submit to argument and demonstration,” but not to human
authority. The real action in this iterated process of dialectical inquiry happens in
formulating and evaluating arguments. We’ll get to this shortly, but first I want us to
examine the personal traits and social conditions that lead to fruitful reasoning based on
our diverse perspectives as ways of thinking.
Conditions for Critical Thinking
We’ve discussed how inquiry draws us towards knowledge and understanding through
sharing and critically reviewing the ideas and arguments that emerge from diverse
perspectives, experiences and ways of thinking. But this doesn’t happen automatically.
Diverse perspectives and ways of thinking can also drive polarization, conflict and
hostility. In this section we want to explore how diversity can be harnessed to mutual
benefit rather than mutual destruction. We’ve already alluded to a few of these
conditions. Here I will list and characterize them more specifically. We’ll start with the
personal traits of effective critical thinkers, or just reasonable people. Then we’ll
consider the social conditions to be found in communities populated by reasonable
people.
• Fallibilism: We mentioned earlier that as subjects we are fallible beings. Our
evidence is limited and we are liable to make mistakes in reasoning. Given our
nature as fallible subjects, we should never be entirely convinced that we have
settled a matter once and for all. To be completely convinced we are right would
lead us to neglect any further evidence and argument that might warrant some
revision of our views.
• Intellectual Humility: Closely related to the idea of fallibilism is intellectual humility.
Intellectual humility goes beyond merely recognizing our capacity for error.
Fallibilism is not directly concerned with our attitudes towards others and their views
and thought processes. Intellectual humility does concern these social factors. The
intellectually humble person will keep ego out of their engagement with other people
in inquiry. Pride and celebration of your excellence is fine in competitive contexts,
but inquiry isn’t a competition, it’s a cooperative activity where respect for others is
critical. Arrogance and pride are liable to drive others from the project of inquiry with
the result of losing their insights and perspectives. Of course, there are times when
someone understands more than others and it may be tempting to see arrogance in
expertise. Dismissing expertise as arrogance, however, will be a failure of
intellectual humility itself. Seeing arrogance in expertise is a self-protective way of
propping up one’s ego by judging another as flawed instead of trying to understand
them and make good use of a learning opportunity. Bear in mind that genuine
expertise is only acquired through the exercise of intellectual humility. This may be
hard to see in people who have some hard-earned expertise, but even the smartest
among us only move past ignorance by humbly yielding to the better argument.
• Open Mindedness: The open-minded person is open to fairly evaluating the
reasons and evidence. Note that open mindedness focuses on our openness to
reasons and evidence. A popular but misguided conception of open mindedness is
that we should never have much confidence in our own beliefs but always grant that
we are just as likely to be wrong as someone who disagrees with us. The problem
with way of thinking about open mindedness is that the person who knows what they
are talking about and holds a view with some conviction as a result of rigorous
inquiry would not count as open minded. You might, for instance, encounter a
climate change skeptic alleging that climate scientists are not open minded because
they are unwilling to consider the possibility the warming of our climate is the result
of sun spots. This is a fallacious attempt to undermine the science. We should hold
our beliefs with as much conviction as the best available reasons and evidence
warrant. Often our reasons justify high levels of confidence, if not absolute
confidence (see fallibilism).
• Intellectual Courage: Reasonable people, being open minded and intellectually
humble, take the risk of discovering that they have things wrong once in a while.
This can be hard. It’s generally not pleasant to find to find that you are mistaken. It
takes intellectual courage to bear this risk with grace. It helps to have a sense of
humor here. It’s best if curiosity and delight in discovery outweigh the dread we often
feel about getting things wrong. But while critical thinking involves a degree of
intellectual risk, it should not involve putting your personal safety on the line in any
way. Critical thinkers attack ideas and arguments, not each other. If somebody
attacks you, they are not being reasonable. It is possible for a person to feel
attacked if they self-identify with an idea that comes under scrutiny. But feeling
personally attacked when an idea you like faces criticism would be a failure of
intellectual humility that results from investing ego into something that isn’t you. You
are not your ideas. You can change your mind about something without being
personally harmed. When reasonable people do change their minds, it will not be
because any other person is dominating or compelling them. Reasonable people
change their own minds in response to compelling reasons, not domineering people.
• Perseverence: Even once we’ve acquired the traits discussed so far, clarifying and
evaluating arguments can be challenging and frustrating work. You might feel this
way about some things some things you’ve already read in this text. For an ounce of
encouragement, bear in mind that confusion is often what it feels like to grow
intellectually. Of course, sometimes things are confusing because they just don’t
make sense. But things that do make sense can feel confusing when they are novel,
abstract or just complicated. Stick with it. That confusion is what it feels like to grow
new neural pathways. You’ll be smarter if you see it through. Even after 40 years of
studying philosophy, I sometimes find myself feeling lost and confused in my first
pass at reading the work of a philosopher I haven’t studied before. Then in the
second reading things will begin to make sense. Take some rest between passes. It
also helps enormously to take notes on how terms are defined and how arguments
are structured. Your brain will continue to sort things out even when you aren’t
actively reflecting on the material. By the third or fourth pass, maybe over the course
of a few days, rich and clear understanding will emerge and you’ll be wiser than you
were before.
Now let’s consider what a community of reasonable people who uphold these
intellectual virtues will look like. I think it will be a community characterized by freedom
from domination, tolerance and respect for diverse others, good humored civility, a
healthy political capacity to deal with shared problems and challenges cooperatively and
effectively, and intimacy in friendship. Let’s consider each of these in more detail.
• Freedom from domination: Critical thinking provides a way of exploring,
understanding and sometimes resolving differences between people. This is an
alternative to bullying, manipulation, deceit and domination. Again, critical thinkers
are responsive to good reasoning and they cultivate intellectual defenses against
rhetorical bullying and propaganda aimed at social control. Critical thinkers will resist
dominating attempts to by-pass their own intellectual capacities through
manipulation or deceit.
• Tolerance and Respect for Diverse Others: People who recognize their own
fallibility and value intellectual humility will recognize that intolerance bars others
from sharing their evidence and argument. This will introduce blind spots in inquiry
and frustrate attempts to understand things and figure things out. Likewise
disrespectful treatment of others is liable to drive them from participating in inquiry
with the same result of ignoring potentially important evidence and argument.
Intolerance and disrespectful treatment of others is literally a recipe for ignorance.
• Politics: I’m sure you have noticed how divisive politics is in America at the
moment. Passionate conflict in politics often reflects a struggle for power aimed at
sustaining or overcoming oppressive domination. But even here, conflict is driven
and amplified by poor critical thinking. The political polarization in we current see in
America is the result of people refusing to try to understand each other and evaluate
each other’s reasons and perspectives fairly. I’m afraid a great many Americans
have become unreasonable people, disastrously poor critical thinkers. If we were
better able to understand and evaluate each other’s perspectives, we would be
much more capable of finding common ground in addressing our shared problems. If
we were better able to identify fallacies, mistakes in reasoning, we would be much
less vulnerable to manipulation that divides us and undermines mutual
understanding.
• Friendship: There may be no more basic human need than the need to be loved.
As subjects, we are doomed to a sort of isolation. No other person, not matter how
well they know you and care for you can share your subjectivity. We can only hope
to understand each other to limited degrees. But I’d submit that the drive to
charitably understand another people is itself a form of love.
This probably sounds idealistic to the point of being unrealistic. That is understandable
given the current state of our world. We face multiple crises from political dysfunction to
climate change and this engenders a great deal of fear and anxiety. In this state, critical
thinking is not just intellectually challenging, but it is likely to feel emotionally remote as
well. When people are fearful and anxious it natural to seek security in the familiar and
defend that against all intrusions. The need for intellectual courage is all the more dire
and may seem to carry with it a need for emotional courage just when this seems least
available. What I want to suggest here, is that we can seek comfort and security not
only in the familiar, but also in the project of building communities of critical thinkers.
This obviously starts with cultivating our own critical thinking skills. And this may require
loosening our grip on ideological security blankets. But as we saw last week in
connection with Russell, clinging to opinions as a security blanket doesn’t really provide
security. A better strategy is to seek comfort and security in friends and loved ones.
Critical thinking provides an avenue to expanding your community of friends and loved
ones even across great differences of perspective.
2. Critical Thinking II: Logic
Philosophers, as we’ve previously mentioned, are mainly in the business of formulating,
clarifying and evaluating arguments. This is how inquiry proceeds. In any realm of
inquiry, this is how we determine what is true, when we can. An argument is a reason
for thinking something is true. An argument consists of a set of premises which work
together to provide a reason for accepting a conclusion as true. In this chapter we will
get introduced to the basic standards and procedures for formulating, clarifying and
evaluating arguments.
We’ve introduced the idea of an argument as a reason for believing something and
most the chapter will focus on this primary function of arguments. But arguments are
multifunction tools in inquiry and we will also want to discuss their various other uses
along the way. Here are a few:
Arguments can be useful for
• Providing a reason for thinking their conclusions are true
• Clarifying our reasons
• Teasing out false premises
• Clarifying our own conceptual understanding
• Recognizing gaps on our own reasoning
• Understanding the views of others
We’ll have to say more about how to clarify and evaluate arguments before explaining
these points.
Arguments
The way to determine whether a claim is true or false, when this is possible, is to
evaluate the evidence and argument for and against it. Sometimes good reasons take
the form of simple observations. I have a good reason for thinking my bicycle has a flat
tire when I see the tire sagging on the rim. But often the business of identifying and
evaluating reasons is a bit more involved.
An argument is a reason for taking something to be true. Arguments consist of two or
more claims, one of which is a conclusion. The conclusion is the claim the argument
aims to establish as true. The other claims, there can be one or many, are the premises.
The premises of an argument taken together are offered as a reason for believing its
conclusion to be true.
Some arguments provide better reasons for believing their conclusions than others. In
case you have any doubt about that, consider the following examples:
1. Sam is a line cook.
2. Line cooks generally have good of kitchen skills.
3. So, Sam can probably cook well.
1. Sam is a line cook.
2. Line cooks usually aren’t paid very well.
3. So, Sam is probably a millionaire.
The premises in the first argument provide pretty good support for thinking Sam can
cook well. That is, assuming the premises in the first argument are true, we have a good
reason to think that its conclusion is true. The premises in the second argument
constitute a pretty poor reason to think Sam is a millionaire. So, whether or not the
premises of an argument support its conclusion is one important factor in evaluating an
argument.
Now consider these examples:
1. Boston is in Massachusetts.
2. Massachusetts is east of the Rockies.
3. So, Boston is east of the Rockies.
1. Boston is in California.
2. California is west of the Rockies.
3. So, Boston is west of the Rockies.
Again, the first of these two arguments looks good, the second not so much. But the
problem with the second of these arguments is different. The premises of both
arguments provide good support for the conclusion. That is, in both arguments, if the
premises were true, we’d have good reason for accepting the conclusion. In fact, for
both arguments, if the premises were true, the conclusion would have to be true. So, in
both of these arguments we have a good relation of logical support between the
premises and the conclusion. But the first premise of the second argument just isn’t
true. Boston is not in California. So, the latter pair of arguments suggests another key
issue for evaluating arguments. Good arguments have true premises.
That is pretty much it. A good argument is an argument that has true premises that
support its conclusion. So, evaluating an argument involves these two steps:
• Determine whether or not the premises are true.
• Determine whether or not the premises support the conclusion (that is, whether
we have grounds to think the conclusion is true if all of the premises are true).
Determining whether an argument’s premises are true may involve evaluating further
arguments in support of those premises. An argument might be the last link in a long
chain of reasoning. In this case, the quality of the argument depends on the whole
chain. And since arguments can have multiple premises, each of which might be
supported by further arguments, evaluating an argument might be more involved yet,
since its conclusion is really supported by a rich network of reasoning, not just one link
and then another. While the potential for complication should be clear, the basic idea
should be pretty familiar. Think of the regress of “why” questions many of us tormented
our parents with as children. Even at a young age we understood that the reasons for
believing one thing can depend on the reasons for believing a great many other things.
However involved the network of reasons supporting a given conclusion might be, it
seems that there must be some starting points. That is, it seems there must be some
reasons for believing things that don’t themselves need to be justified in terms of further
reasons. Otherwise, the network of supporting reasons would go on without end. The
issue we are facing here is one of identifying the ultimate foundations of knowledge and
justified belief. This is a big epistemological issue and we will return to it later in the
course. For now, let’s consider one potential answer we are already familiar with. In the
sciences our complex chains of reasoning seem to proceed from the evidence of the
senses. We think that evidence provides the foundation for our edifice of scientific
knowledge. Sounds great for science, but where does this leave philosophy? Does
philosophy entirely lack evidence on which its reasoning can be based?
Philosophy does have a kind of evidence to work from and that evidence is provided by
philosophical problems. When we encounter a problem in philosophy this often tells us
that the principles and assumptions that generate that problem can’t all be correct. This
might seem like just a subtle clue that leaves us far from solving the big mysteries. But
clues are evidence just the same. As we will discuss in our chapter on the philosophy of
science, science doesn’t really have it much easier. Sensory evidence by itself doesn’t
tell us as much about the nature of the world as we often suppose. Scientific evidence
provides clues, but there remains a good deal of problem solving to do in science as
well as in philosophy.
So, we can assess the truth or falsity of the premises of an argument by examining
evidence or by evaluating further argument in support of the premises. Now we will turn
to the other step in evaluating arguments and consider the ways in which premises can
support or fail to support their conclusions. The question of support is distinct from the
question of whether the premises are true. The reason one of our arguments about Sam
the line cook was good but not the other had nothing to do with false premises. We can
grant that the premises in both arguments were true. The difference had to do with
whether the premises provided good support of the conclusion. When we ask whether
some premises support a conclusion, we are asking whether we would have good
grounds for accepting the conclusion if we assume that the premises are true. It is
important that we keep the two steps in evaluating arguments distinct in our minds.
When we evaluate arguments wholistically, as people often do, we wind up accepting or
rejecting arguments based on how we feel about them overall without looking into
whether the premises of the arguments really support the conclusions we draw. This is
one of the ways we fall victim to confirmation bias, by endorsing just the arguments that
point towards the conclusions we like without scrutinizing the logic of the argument.
Consider again the two good arguments in our examples above:
1. Sam is a line cook.
2. Line cooks generally have good of kitchen skills.
3. So, Sam can probably cook well.
In this example the premises do support the conclusion. We have pretty good reason to
think Sam can cook well if he is a line cook. But these premises don’t guarantee that
Sam can cook well. It might be his first day on the job. He might be a really lousy line
cook. Or he might be a breakfast cook and pretty useless in the kitchen beyond frying
eggs and making hash browns. Still, the premises of this argument would give us good
reason for trusting him with dinner. The premises being true would make it pretty likely
he’d feed us well.
Now consider this one again:
1. Boston is in Massachusetts.
2. Massachusetts is east of the Rockies.
3. So, Boston is east of the Rockies.
In this argument the premises don’t just make the conclusion likely. The premises being
true would guarantee the truth of the conclusion. These two examples point us towards
our two standards of support, deductive validity and inductive strength. A deductively
valid argument is one where the premises, if they are true, would guarantee the truth
conclusion. The support relation in the case of deductively valid arguments is logically
necessary. Inductively strong arguments are arguments where the premises, if they are
true, would provide good reasons for thinking the conclusion is true. But good reasons
in inductively strong arguments are a matter of probability, not necessity. A strong
inductive argument with true premises doesn’t guarantee the truth of the conclusion.
Deductive Validity
The deductive standard of support is validity. An argument counts as deductive
whenever its aiming at validity. Deductive validity is the strictest standard of support we
can uphold. In a deductively valid argument, the truth of the premises guarantees the
truth of the conclusion. Here are two equivalent definitions of deductive validity:
(D) A valid argument is an argument where if its premises are true, then its
conclusion must be true.
(D’) A valid argument is an argument where it is not possible for all of its
premises to be true and its conclusion false.
Here are a few examples of deductively valid arguments
1. If Socrates is human, then Socrates is mortal
2. Socrates is a human.
3. Therefore, Socrates is mortal
1. All monkeys are primates
2. All primates are mammals
3. So, all monkeys are mammals
If you think about these two examples for a moment, it should be clear that there is no
possible way for the premises to all be true and the conclusion false. The truth of the
conclusion is guaranteed by the truth of the premises. In contrast, the following
argument is not valid:
1. If Sue misses her plane, she will be late for the conference.
2. Sue is late for the conference.
3. Therefore, she missed her plane.
Again, to say that an argument is deductively valid is to say that it is impossible for all of
its premises to be true and its conclusion to be false. To see why the last argument is
not valid, try to think of a possible scenario that makes both of the premises true and the
conclusion false. One scenario is where Sue catches her plane, but her cab from the
airport gets stuck in traffic. Another would be where Sue makes her flight, but the plane
is delayed due to bad weather. If we can think of any possible way for the premises of
an argument to be true and its conclusion false, then we have shown that the
conclusion does not deductively follow from the premises. That is, we’ve shown that the
argument is not valid.
Our intuitive test for validity is to think about whether it is possible for the argument’s
premises to be true and its conclusion to be false. A key point to notice here is that
validity is not directly about the truth or falsity of the premises or the conclusion. The
concept of validity is really a concept about what is and isn’t logically possible. A
deductively valid argument may or may not have true premises. Consider this argument:
1. All planets are stars.
2. All stars are bodies that shine steadily.
3. All planets are bodies that shine steadily.
Both of the premises in this argument are false, but the argument is still valid. Suppose,
contrary to fact, that the premises were true. The conclusion would have to be true if
this were the case. Validity isn’t about whether the premises or the conclusion are in
fact true. It is only about whether the conclusion logically follows from the premises.
Given this, a deductively valid argument only provides one with a good reason for
believing its conclusion if its premises are true. If a deductively valid argument has all
true premises, we say that it is deductively sound. For an argument to be deductively
sound is one way for it to pass both steps for evaluating arguments. A deductively
sound argument has all true premises that support its conclusion.
The deductive arguments we’ve looked at here are pretty intuitive. We only need to
think about whether the conclusion could be false even if the premises were true. But
most deductive arguments are not so obvious. Logic is the science of deductive validity.
Philosophy has made some historic advances in logic over the past century. Bertrand
Russell, who we got acquainted with in the last chapter, was among the key contributors
to developments in logic early in the 20th century.
Logical Form
Since Aristotle, the first major logician, it’s been recognized that deductive validity is a
matter of an argument’s logical form. We can display an argument’s logical form by
replacing all but the logically operative vocabulary with symbols (we’ll use capital letters
for this). So, consider the logical form of a few of our examples so far.
1. All planets are stars.
2. All stars are bodies that shine steadily.
3. All planets are bodies that shine steadily.
This argument has the following form:
1. All P are S
2. All S are B
3. All P are B
Any argument that has this logical form will be valid. So,
1. All fish are vertebrates.
2. All vertebrates are animals.
3. So, all fish are animals.
Remember, validity is just a standard of support. Validity does not assume true
premises or a true conclusion. So even though it sounds a bit “off,” this argument is also
valid:
1. All red things are bricks,
2. All bricks are rocket ships.
3. So, all red things are rocket ships.
Of course, this argument sounds silly. Both premises are ridiculously false. But then any
possible world where both premises are true would be a possible world where all red
things are rocket ships. The argument is valid in virtue of its valid logical form. Now
consider this familiar argument:
1. If Socrates is human, then Socrates is mortal
2. Socrates is a human.
3. Therefore, Socrates is mortal
This argument has the following logical form:
1. If H, then M
2. H
3. M
Similarly, any argument that has this logical form will be valid. Plug any declarative
sentences you like in for H and M and you will have a valid argument. The premises
might be false, or even absurd, but it will remain the case that any way the world could
be that makes both premises true will also make the conclusion true. Once you
appreciate how deductive validity is a function of the logical form of an argument, it soon
becomes clear that a valid argument can be constructed for any possible conclusion,
true, false, or completely absurd. So, for instance:
1. If pigs fly, then the oceans will dry up.
2. Pigs fly
3. Therefore, the oceans will dry up.
So, you might be wondering what the point of all this silliness is. It’s partly to limber up
your logical sense and help you recognize that logical validity is only about what follows
from what, not about what is in fact true or false. Of course, the oceans aren’t going to
dry up. But if both premises were true, then the conclusion would follow logically and
also be true. But there is a further point to the hypothetical silliness. The fact that the
conclusion of the “pigs fly” argument is absurdly false is a good indicator that at least
some of the premises of this valid argument are also false. And this is a very useful
thing to recognize. To see this, let’s look at another valid argument pattern that captures
what we’ve just said about the pigs fly argument:
1. If P, then C
2. Not C
3. So, not P
This is a valid pattern of reasoning that we use routinely. For instance:
1. If I have milk, then it will be in the fridge
2. There’s no milk in the fridge
3. So, I am out of milk.
Now notice how we used this pattern of reasoning in our analysis of the “pigs fly”
argument. It is valid, which means that if its premises are all true, then its conclusion is
true. But obviously, its conclusion isn’t true. So, its premises are not all true.
Reductio ad Absurdum
I mentioned near the beginning of this chapter that arguments are multifunctional tools
in inquiry. Arguments aren’t always used directly to show the truth of some conclusion.
As we’ve just seen, the concept of a valid argument can be used to tease out falsity in
the premises. For instance, we might consider a claim that sounds pretty good and ask
what follows from that claim deductively. What conclusion could we validly argue for on
the basis of that claim? If we find that by deductively valid reasoning we can get from
our claim that sounds pretty good to an absurd conclusion, then we have shown that our
starting point, the claim that sounded pretty good, is false. This strategy is known as
reductio ad absurdum, which is a handy bit of Latin for “reducing to absurdity.” We can
use this strategy to test an idea for problems by considering what follows from that idea
by valid argument and making sure it doesn’t lead to anything obviously false or absurd.
To illustrate reductio ad adsurdum, let’s consider a view we mentioned briefly in the first
chapter of this text about the nature of morality. A view that many people find attractive:
moral relativism. According to moral relativism, there are no objective moral standards,
rather morality is relative to groups depending on what is considered right in that group.
When we consider what follows from moral relativism deductively, we wind up with
some pretty unsavory results. The first premise in this argument is just a statement of
moral relativism as a view about the nature of morality. From here, bad things start to
happen.
1. If a society considers something morally good, then it is morally good (relative to
that society).
2. Nazi Germany considered the extermination of Jewish people good.
3. The extermination of Jewish people was good (relative to Nazi Germany).
The argument here is valid. It’s logical form is a minor variation on a valid pattern we
examined above. If the premises are true, then the conclusion must be true. This means
that if the conclusion is false, at least one of the premises must be false. Note that the
conclusion here is not about what the Nazis considered to be good, its about what is
good in the only sense that matters according to moral relativism. Since the conclusion
of this argument is obviously false, not to mention horrible, and the second premise is a
matter of historical fact, moral relativism must be false. Here we have reasoned validly
from a view about the nature of morality that many people find attractive to a conclusion
that is obviously absurdly false and horrible. A view about the nature of morality that has
obviously and horribly bad logical consequences has got to be false. Moral relativism
reduces to absurdity, reductio ad adsurdum. We will get to examine moral relativism in
greater detail when we get around to studying ethics. The point here is just to see how
deductive argument is useful not just for getting at true conclusions, but also for teasing
out false premises using the strategy we’d just identified as reductio ad absurdum.
Revealing Hidden Assumptions
Another very helpful function of valid argumentation is as an aid to revealing hidden
assumptions. In everyday life we don’t generally formulate formally valid arguments
when we give reasons for what we believe. And often these unmentioned premises are
where our biases hide. A good understanding of deductively validity can help us bring
these hidden assumptions and biases to light. For example:
1. Every story I hear about politician X on Facebook says he is doing a terrible job.
2. So, Politician X is doing a terrible job.
This is not a valid argument as it stands. We would have a valid argument if we added a
premise as follows.
1. Every story I hear about politician X on Facebook says he’s doing a terrible job
2. If every story I hear about politician X on Facebook says he’s doing a terrible job,
then politician X is doing a terrible job.
3. So, Politician X is doing a terrible job.
Now we have a valid argument, but adding the premise required to have a valid
argument reveals a hidden assumption that, as some of you probably know, we have
reason to doubt. Facebook uses AI and algorithms to customize what you see in order
to maximize engagement. It turns out that anger is very engaging. As a result,
Facebook tends to feed you news stories that will stoke your anger. If you have a
history of clicking and commenting on stories that say awful things about politician X or
others of his political persuasion, Facebook will load your news feed with more articles
that say awful things about politician X. The same goes for Google, YouTube and most
search engines and social media platforms. The reason Facebook keeps showing you
stories about what a terrible job politician X is doing isn’t that politician X is actually
doing a terrible job. Rather its that the AI behind Facebook algorithms knows that
stories like this will keep you glued to the platform, posting angry comments about
politician X.
So, formulating deductively valid arguments brings our assumptions to light where they
can be scrutinized for truth or reasonableness. A good understanding of deductive
validity can be very useful in identifying and addressing our usually unspoken
assumptions and biases (well, perhaps in the example we just considered, the bias lies
mainly in the AI driven algorithms employed by Facebook).
Clarity
For reasons we just been discussing, a good understanding of deductive validity can
help you clarify your own reasons and express them clearly to others. If you can
recognize when an argument you find appealing has some deductive gaps in it, your
understanding of validity will guide you in filling in those gaps. Assuming the argument
is a good one, you will then have a clearer understanding of it and be able to express
your reason more clearly to others. Of course, as just discussed, if your argument is not
so great, your understanding of validity can alert you to this and perhaps guide you in
formulating a better argument. All of this applies to understanding the arguments offered
by others. When others formulate their reasons in incomplete, less than valid ways, your
understanding of validity can guide you in identify the questions you’d want to ask in
reconstructing a more complete version of your friend’s argument.
Charitable Interpretation
A good understanding of deductive validity will help you formulate the clearest and best
possible arguments for your view. It will also help you formulate and appreciate the best
possible arguments for views you oppose. Formulating the best possible interpretation
of and argument for opposing views is what we call “charitable interpretation. In the
dialectical spirit of cooperatively working towards truth and reasonableness, it is best to
be charitable in filling out your reconstruction of another’s reasons. While helping to
clarify arguments is a kindness, this is isn’t really the point of charitable interpretation.
Finding faults with bad arguments for a view you disagree with doesn’t really undermine
that view, it just undermines bad arguments for that view. If you have good reasons for
rejecting a view, you should aim to identify the flaws in the best possible arguments for
the view you think is wrong. Trying to make the opposing view sound outrageous or
ridiculous will only lead you into straw man attacks (see discussion of the fallacy below).
The strongest argument you can offer against a view you oppose is not the argument
that makes the view sound outrageous, but the argument that targets the best
interpretation of the opposing view and the best possible arguments for it. Being a
reasonable and effective critical thinker calls for charitable interpretation of opposing
views and the arguments for them, not just out a sense of fair mindedness, good as that
may be, but also in order to be the most effective critic of the view you oppose.
In the last few sections, I’ve tried to characterize a few useful functions for deductive
argumentation beyond merely trying to give reasons for thinking that something is true.
While sound arguments, arguments that are both valid and have all true premises,
provide good reasons for accepting their conclusions as true, valid argument isn’t only
useful for directly getting at the truth. A good understanding of validity is useful for
clarifying reasoning and bringing hidden assumptions to the surface. It can be useful for
drawing our attention to false premises. And it can help us make our criticism of views
we oppose more effective by targeting the best versions of those views. The path to
knowing truths and understanding issues is usually not a straight paved sidewalk. It
takes some skill to recognize the switchbacks and stay on the trail. A good
understanding of deductive validity is powerful guide.
Inductive Strength
I won’t have as much to say about inductive strength and cogency since you will already
be more familiar with it from science classes and because philosophy trades more in
deductive argument. Let’s start with our example argument from above:
1. Sam is a line cook.
2. Line cooks generally have good of kitchen skills.
3. So, Sam can probably cook well.
This is a decent argument. The premises do support the conclusion. And yet it might be
that both premises are true and the conclusion is false. Sam could be a brand new
cook, hired because he’s the manager’s son, but also someone who has never cooked
in his life. Many arguments give us good reasons for accepting their conclusions even
when true premises don’t guarantee the truth of the conclusion. This suggests that we
need another standard of support for arguments that aim at giving us pretty good but
not absolutely compelling grounds for accepting their conclusions. And this standard of
support is called inductive strength. Here are two equivalent ways of defining inductive
strength:
(I) An inductively strong argument is an argument in which if its premises are
true, its conclusion is probably to be true.
(I’) An inductively strong argument is an argument in which it is improbable that
its conclusion is false given that its premises are true.
If you look again at the earlier definitions for deductive validity you will find a good deal
of similarity. The only difference is in the use of the words “probably” rather than “must
be” in the first definition, and “improbable” rather than “impossible” in the second. This is
a big difference. As in the case of validity, when we say that an argument is strong, we
are not assuming that its premises are true. We are only claiming that if the premises
are true then the conclusion is likely to be true. Corresponding to the notion of deductive
soundness, an inductive argument that is both strong and has true premises is called a
cogent inductive argument. Unlike the case if deductively sound arguments, it is
possible for an inductively cogent argument to have true premises and a false
conclusion.
What makes an argument an inductive argument is that it is aiming at the standard of
inductive strength. Similarly, what makes an argument a deductive argument is aiming
at validity. Students frequently ask if an invalid deductive argument can be considered
inductively strong. Generally, not. The targets are different. Missing the target of
deductive validity doesn’t make an argument inductively strong. Invalid deductive
arguments are generally just bad arguments. Once in a while there will be a decent
inductive argument that looks a bit similar, but not typically. Deductive and inductive
refer to different kinds of reasoning.
Lots of good reasons for holding a belief fall short of the standard of deductive validity.
The sort of reasoning you were taught as “the scientific method” is inductive reasoning.
As it is taught in high school, the scientific method consists of formulating a general
hypothesis and testing it against a large sampling of data. If the data is consistent with
the hypothesis, then the hypothesis is considered confirmed by the data. Here a limited
amount of evidence is taken to support a broader more general hypothesis. In the
simplest case, inductive reasoning involves inferring that something is generally the
case from a pattern observed in a limited number of cases. For instance, if we were to
conduct a poll of 1000 Seattle voters and 600 of them claimed to be Democrats, then
we could inductively infer that 60% of the voters in Seattle are Democrats. The results
of the poll give a pretty good reason to think that around 60% of the voters in Seattle are
Democrats. But the results of the poll don’t guarantee this conclusion. It is possible that
only 50% of the voters in Seattle are Democrats and Democrats were, just by luck, over
represented in the1000 cases we considered.
When evaluating deductive arguments for validity we ask if it is possible for the
premises to be true and the conclusion to be false. This is either possible or it isn’t.
Possibility does not admit of degrees. But probability does. The truth of the conclusion
of an inductive argument can be probable to a greater or lesser degree. An argument
either is or isn’t valid. But inductive arguments can be more or less strong. We can
identify a few factors that bear on the degree of strength an inductive argument has.
One is how much evidence we have looked at before inductively generalizing. Our
inductive argument above would be stronger is we drew our conclusion from a poll of
100,000 Seattle voters, for instance. And it would be much weaker if we had only polled
100. Also, the strength of an inductive argument depends on the degree to which the
observed cases represent the makeup of the broader class of cases. So our inductive
argument will be stronger if we randomly select our 1000 voters from the Seattle phone
book than if they are selected from the Ballard phone book (Ballard being a notably
liberal neighborhood within Seattle).
So far, we’ve only discussed inductive generalization, where we identify a pattern in a
limited number of cases and draw a more general conclusion about a broader class of
cases. Inductive argument comes in other varieties as well. In the example we started
with about Sam the line cook, we inductively inferred a prediction about Sam based on
a known pattern in a broader class of cases. Argument from analogy is another variety
of inductive reasoning that can be quite strong. For instance, I know that my housecat is
very similar to cougars in the wild. Knowing that my cat can jump great heights, it would
be reasonable to expect that by analogy, or based on this similarity, cougars can jump
well too.
There are further varieties of argument that aim at the standard of inductive strength,
but we will discuss just one more in detail now. Abduction is inference to the best
explanation. Detective work provides a good example of abductive argument. When
Holmes discovers Moriarty’s favorite brand of cigar and a bullet of the sort fired by
Moriarty’s gun at a murder scene, inference to the best explanation suggests that
Moriarty was the killer. That Moriarty committed the murder provides the overall best
explanation of the various facts of the case.
The 19th century American pragmatist and logician, Charles Sanders Peirce offers
the Surprise Principle as a method for evaluating abductive arguments. According to the
surprise principle, we should count one explanation as better than competing
explanations if it would render the facts we are trying to explain less surprising than
competing explanations. The various clues in the murder case are among the facts we
want explained. The presence of the cigar and the bullet casing at the murder scene is
much less surprising if Moriarty committed the murder than if the maid did it. Inference
to the best explanation aims at strength. So a strong abductive argument in this case
needn’t rule out the possibility that the murder was committed by Moriarty’s evil twin
who convincingly frames his brother. There might an argument against the death
penalty lurking nearby. Inference to the best explanation is worth more attention than if
often receives. This kind of reasoning is pervasive in philosophy and science, but
seldom gets much notice as an integral part of the methods of rational inquiry.
Fallacies
A fallacy is just a mistake in reasoning. Humans are not nearly as rational as we’d like
to suppose. In fact, we are so prone to certain sorts of mistakes in reasoning that
philosophers and logicians refer those mistakes by name. In this section we’ll get
acquainted with a choice selection of all-to-human irrational tendencies. For thorough
catalogue of logical fallacies, I’ll refer to you The Fallacy Files
(http://www.fallacyfiles.org/taxonomy.html).
• Ad hominem: This fallacy is known is Latin for “against the person.” As the name
suggests, ad hominem consists of attacking the proponent of a position rather than
critically evaluating the reasons offered for the proponent’s position. The reason ad
hominem is a fallacy is that the attack on an individual is simply not relevant to the
quality of the reasoning offered by that person. Attacking the person who offers an
argument has nothing to do whether or not the premises of the argument are true or
whether they support the conclusion. Ad hominem is a particularly rampant and
destructive fallacy in our society. What makes it so destructive is that it turns the
cooperative social project of inquiry through conversation into polarized verbal
combat. This fallacy makes reasonable dialogue impossible while it diverts attention
from interesting issues that often could be fruitfully investigated.
Here’s an example of ad hominem: A car salesman argues for the quality of an
automobile and the potential buyer discounts the argument with the thought that the
person is just trying to earn a commission. There may be good reason to think the
salesman is just trying to earn a commission. But even if there is, this is irrelevant to
the evaluation of the reasons the salesman is offering. The reasons should be
evaluated on their own merits. We can imagine a situation where the salesman is
just trying to earn a commission and yet he is also making good arguments.
Consider a salesman who is not too fond of people and cares little for them except
that they earn a commission for him. Otherwise, he is scrupulously honest and a
person of moral integrity. In order to reconcile himself with the duties of a sales job,
he carefully researches his product and only accepts a sales position with the
business that sells the very best. He then sincerely delivers good arguments for the
quality of his product, makes lots of money, and dresses well. Perhaps this is an
unusual situation. Perhaps this salesman was a philosophy major. The customer
who rejects his reasons for buying the car he sells on the ad hominim grounds that
he is just trying to earn a commission misses an opportunity to buy the best. The
moral of the story is just that the salesperson’s motive is logically independent of the
quality of his argument. Of course, to know this, you’d want to also read some
reviews, study the car yourself and make sure his premises check out.
• False Dichotomy: A dichotomy is an either/or choice where this is no third or fourth
option. We’ve seen an example of a dichotomy in the contrast between the claim
that there is intelligent life on other planets and the claim that there is no intelligent
life on other planets. If one option is false then the other is true. There is no third or
fourth possibility. On the other hand, when you go to a restaurant and you are trying
to decide between the Impossible Burger or the Caesar Salad, you are probably not
facing a dichotomy. You also have the option of having the salmon, or perhaps the
fajita. The fallacy of false dichotomy is committed when we are presented with just
two options as if these were the only possibilities when in fact there may be a third,
forth or more other possibilities.
So here is a famous example of the false dichotomy fallacy. Shortly after 911,
George W. Bush proclaimed, “You are either with us or you are with the terrorists.”
Not long after that Bush launched a war against Iraq in the name of fighting
terrorism. Some American’s protested the invasion of Iraq, arguing that we did not
have good reason to feel threatened by that country and that given this, an unjust
war would inspire more terrorism than it prevented. People who protested the
invasion of Iraq were roundly vilified as “terrorist sympathizers.” In fact, critics of the
war in Iraq were as opposed to terrorism as the rest of America, they simply doubted
that the Bush administration’s invasion of Iraq would be an effective way to combat
terrorism. As it turns out, Iraq did not have the weapons of mass destruction it was
alleged to have and it was not at the time a sponsor of terrorism (though many
members of Iraq’s disbanded military went on to join terrorist organizations after we
invaded Iraq). The long war in Iraq took an enormous toll on human life and wellbeing both to US and international service personnel but mostly to Iraqi citizens.
With a long-term price tag of around 2 trillion for US tax payers it was enormously
expensive. The war badly damaged US standing on the international stage. And it
inspired a great deal of terrorism, mostly in Iraq and then Syria, often targeting US
military personnel but also civilians. Critics of the war here in the US were not either
with the Bush administration or with the terrorists. They shared the Bush
administration’s goal of ending terrorism but opposed it’s strategy for achieving this
goal.
• Straw Man: When soldiers fought with bayonets on their rifles, they would train by
attacking straw men. Straw men are fairly easy to stab with a bayonet since they
don’t run away or fight back. But then stabbing a straw man is no victory over an
actual opponent. The fallacy of straw man is committed when someone criticizes an
easy to attack distortion of an argument or idea rather than the actual view. Like
many fallacies, this one can be committed deliberately or inadvertently. In our highly
polarized social media environment, it is not uncommon for a disingenuous
manipulator to deliberately broadcast a straw man attack (or some other fallacy) all
the while knowing that his audience, lacking well developed critical thinking skills,
will fall for the manipulation and go on to propagate the bad argument sincerely. This
is often how propaganda works.
You may have heard a commonly propagated straw man attack committed against
efforts to address climate change. Critics will often charge that people concerned
about the environment are really just socialists looking to take our freedom away.
There’s a lot going on here and its worth pointing out the fallacies are gregarious. It
is quite possible to commit more than one at a time. So, you might also notice an
element of ad hominem in this example where reasons for taking climate seriously
get ignored in favor of attacking the people trying to do so. This sheds some light on
the old quip that lies travel half way around the world before the truth gets its shoes
on. It takes lots more work to diagnose and filter out fallacies than it does to commit
and propagate them. But aside from the ad hominem attack, this notion that people
who want to see action on climate change are just big government lovers includes a
straw man distortion of the climate advocates actual views. Yes, addressing climate
change is going to require strong government action and regulation of the use of
fossil fuels, eventually replacing them altogether. The straw man does look
something like the government loving enemy to people who commit this fallacy. The
fallacy wouldn’t work without this resemblance. But climate advocates don’t just love
big government and freedom infringing regulation. They rather recognize a dire and
pressing systemic global problem and they recognize that it can only be addressed
by coordinated government action. Many of them accept the necessity of regulation
with reluctance. Private and individual efforts to address climate change are certainly
helpful, perhaps also necessary. But the climate problem is not really going to get
addressed without effective policy that can only get enacted and administered
through government.
There are many more fallacies worth getting familiar with. I’ll leave you to explore these
on your own. The The Fallacy Files is a good place to start. I’ll wrap up here with a brief
mention of confirmation bias. Confirmation bias isn’t really a fallacy because it isn’t a
specific kind of mistake in reasoning. Confirmation bias is the intellectual bad habit of
endorsing just the evidence and argument that seems to support the view you already
hold. Just about any fallacy can be involved in confirmation bias. Confirmation bias is
about what you’d expect to see among people who lack strong critical thinking skills.
People who don’t know how to evaluate arguments have little else to go on except to
prefer the arguments with conclusions they like. The only defense anyone has against
confirmation bias is building some critical thinking skills, learning some logic and
learning to identify fallacies.

Published by

Write

View all posts