PHIL 201
THE CHALLENGE OF SKEPTICISM TRANSCRIPT
S1:
Hello, and welcome to another presentation in Philosophy 201: Philosophy and Contemporary
Ideas. I’m Dr. Mark Foreman. We are in the process of talking about knowledge. Epistemology is
the unit that we’re dealing with at this point. In our last presentation, we defined knowledge as
“justified, true belief.” What I want to do on the next several presentation is take that definition
apart and examine each element of it. I want to talk about beliefs, I want to talk about what we
mean by truth, and I want to talk about this idea of justification. However, before we do that, I
want to first look at a view that basically says we have no knowledge. That view is called
skepticism.
S2:
What is skepticism? Skepticism is the view that says we should suspend judgment concerning
knowledge claims. It basically says that we have no knowledge. There are different varieties—
different kinds—of skepticism:
One kind is simply Common Sense Skepticism. This is a healthy kind of skepticism that
we all tend to have when we hear stories of things out of the ordinary. When somebody
claims, for example, that they saw Elvis, or that the moon landing was a hoax and didn’t
really happen, or somebody claims that they’ve seen a ghost. You know, we all kind of sit
back—we all kind of get skeptical about that. We wonder if that’s really true. There’s
nothing wrong with a healthy sort of skepticism in this sense of the word.
However, what we want to talk about here more is a Philosophical Skepticism. Now,
philosophical skepticism surrounds what’s called the skeptical thesis: no one knows
anything. And there are different kinds of philosophical skepticism:
oOne kind is called unmitigated skepticism. Unmitigated skepticism says that the
skeptical thesis is true (the thesis that no one know anything) and I know it is true.
This is sometimes referred to as absolute skepticism because it’s claiming to know
absolutely that no one knows anything at all. Or sometimes it’s referred to as
global skepticism. Global skeptics deny that we know there is an external world
out there, or that there are other minds out there, that we have free will, or
whether there are souls or anything like that. They claim that we can’t know
anything at all about the world that we experience. It’s universal doubt about
everything. This is also sometimes referred to as Pyrrhonic skepticism, named
after Pyrrho, who was a Greek philosopher who adopted this idea of skepticism.
oAnother type of skepticism is called mitigated skepticism. Mitigated skepticism
says that the skeptical thesis is true (no one know anything), but it wants to hedge
a little bit. It doesn’t want to claim to know that that’s true. He says, “I don’t
know that this is true, but I believe that it’s true that no one knows anything.”
Now mitigated skepticism sees already a problem that maybe some of you have
already seen with the unmitigated skeptic. Which is, if no one knows anything,
how do you know that? We’re going to talk a little bit about that when we talk
about some of the problems with skepticism in a little while. But mitigated
skepticism tries to escape that problem by saying, “I’m not claiming to know that
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no one knows anything; I just believe no one knows anything.” We’ll see if the
mitigated skeptic is able to escape that problem as well.
oA third type of skepticism is called metaphysical skepticism. The metaphysical
skeptic doesn’t want to claim that no one knows anything. He wants to say, “Well,
okay, there are some things I can know. But not much. And what I can know about
them isn’t much [basically analytical and empirical truths]. But I cannot know
other things [any sort of metaphysical truths].” This is sometimes referred to also
as local skepticism: I can know some things, but not other things.
Let’s look at some examples of philosophers who were skeptics.
S3:
One example of the global skeptic would be the French philosopher René Descartes—especially
his famous “search for certainty.” As a matter of fact, that represents the classical ideal of how
the global skeptic thinks. Now, you need to know a little bit about Descartes here. Descartes
lived during a time when a lot of things were being questioned. A lot of truths that had been
assumed for so many years by people were now open to doubt and questioning. And he began to
question, himself. He wondered, could we find something for certain? Is there any way that we
can find certain knowledge? And he was driven by this idea of finding knowledge 100% for
certain. Now, Descartes wondered how one would do that. He thought the best way to find
certain knowledge was to turn the question around and say, “What can I doubt? If I can doubt
something, I know that I cannot have certain knowledge about that.”
By doubt , here, what Descartes meant was it is possible I could be wrong about this. If it’s
possible that I could be wrong about it, that means I can doubt it. And if I can doubt it, then I
can’t have certain knowledge of it. So he began to start doubting all of his knowledge. As a
matter of fact, he went through kind of a systematic version of doing this (we call this systematic
doubting), where he doubted all of the knowledge that he possibly had.
He started off with the knowledge he gained with his senses—what he could see, what he
could hear. And he said, “Is it possible that my senses could be wrong about the
information that’s communicated to me? Have I ever had that experience?” Well, we’ve
all maybe had that experience at one time or another where our senses were wrong about
something—where we thought we saw something, but in fact did not see it at all. One
time I remember walking into my shed that I had in back of my house. Looking in the
corner, I thought I saw a snake, so I ran out of the shed and came back in with a rake to
grab the snake. And it turned out that it wasn’t a snake at all. It was a rope that was curled
up in the corner of my shed. And simply because I came out of the bright light into the
dark, I thought I saw something that, in fact, wasn’t there. My senses communicated
incorrect information to me. That happens once in a while. But wait a second: if it
happens once in a while, then I can’t have certain knowledge from my senses. I can doubt
what my senses tell me. Therefore, Descartes says, I am not going to arrive at any certain
knowledge through my senses.
He then said, “Is it possible that I can doubt what my reason tells me?” Reason tells me a
lot of things about mathematics and things like that, but have I ever made mistakes in
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reasoning? Of course I have: I have made a mathematical error when I’ve tried to do
some things like that, or I’ve reasoned something through and found out it wasn’t true. I
can make mistakes in reasoning. If I can make mistakes—if it’s possible I can be wrong
—then I can doubt what reason tells me.
Now, if you think about it, if we take away our senses and we take away our reason, we’ve taken
away an awful lot of how we arrive at knowledge. Therefore, now the question becomes, can I
really know anything at all? But Descartes didn’t stop there; he went on and added a couple of
other things.
He said, Maybe it’s possible that I’m dreaming everything I’m going through. I have very
lively dreams, and at the time that I’m having those dreams, I think they’re real. Maybe
what’s going on right now is nothing more than a very lively dream, and I’m just
dreaming the world that I’m in right now.
He even went on to suggest the possibility of what he called the “Evil Demon
Hypothesis.” This is a very famous hypothesis. Descartes said, Maybe there is an evil
demon that is actually out there controlling the world that I experience. And that, in fact,
none of this is really true; it’s just being manipulated by this evil demon.
Now in modern times, this Evil Demon Hypothesis becomes very famous as what’s
called the “Brain-in-the-Vat Hypothesis.” This hypothesis basically says this: your brain
inside your head is connected to your senses through a bunch of neural networks (just
like wires). What my eyes see is translated into some sort of electric impulse that goes
through this neural network, goes up into my brain, and tells my brain what I’m seeing.
Let’s suppose we were to take your brain out of your head, place it into a vat of fluid that
would keep your brain alive and functioning, and instead of plugging the neural network
into your senses (your eyes, your ears, smell), we plugged it instead into a large super-
computer that can also take these electric impulses and put them into your brain. Now
sitting at the console of this computer is a scientists, and he’s inputting data into the
computer, so that, in fact, when you look out and see something in the world, it’s not
really out there, it’s just the computer communicating that electric information to your
brain. What you hear, what you feel, what you smell—they’re all connected to this big
computer. So you may think that you’re walking outside in the sun, but in fact that is
simply not true. The computer is just giving you that sense, that input. Is that possible?
Well, certainly we could argue that it’s possible. If that’s possible, it seems I can’t know
anything that’s going on in the world at all—that none of this stuff is really real. Now if
this sounds like a familiar hypothesis to you, it was recently made into a movie a few
years ago called The Matrix. The Matrix was just taking Descartes old “Evil Demon
Hypothesis” and making it into a motion picture so we can all understand that. How
would a person who is trapped in this kind of situation really know anything about reality
at all? He would assume that everything out there is real because that is what his brain is
experiencing. But how would he know that he’s really experiencing that particular stuff?
(Here’s an example, by the way, of philosophy being made popular in Hollywood.)
So, Descartes comes to a conclusion here: I can’t have certain knowledge about anything. If all
of this is possible, if I can doubt all of this in this way, then, in fact, can I arrive at any certain
knowledge? Now, we don’t want leave Descartes hanging here. Descartes didn’t actually come to
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this as his ultimate conclusion. This kind of became his “sub-conclusion.” He goes on from here,
and we’re going to talk about that in another presentation. But at least this idea of systematic
doubt gives you a good idea of how the global skeptic tends to think about the world: I can pretty
much doubt away all of my knowledge of the world.
S4:
Whereas Descartes represented the global skeptic in his search for certainty, Hume is a great
example of the local skeptic, the person who believes we can have some knowledge of some
things, but there are some things we can’t know at all. David Hume was a philosopher who
basically divided knowledge into two kinds of knowledge:
1. First of all, he said, is what we call relations of ideas: these are ideas that are logically
true, and therefore certain, but they actually tell me nothing about reality at all.
Mathematics and definitional concepts fall into this idea. For example, let’s take the
concept that all triangles have three angles. That’s a mathematical concept that is true by
definition—the definition of a triangle is a three-angled thing. Therefore, for me to say all
triangles have three angles is true by definition. And I know that it’s certainly true or
logically true because it’s impossible for something to be a triangle (three-angled thing)
and not have three angles. So it’s logically true. But in fact, this logical truth tells me
nothing about reality. That would be true if no triangles existed at all—if there weren’t
any triangles at all, it would still be true that triangles would have three angles because
it’s simply the definition of what triangle means. That’s what Hume means when he says
that they are logically true and certain, but they don’t tell me anything about reality.
2. Now the other kind of knowledge that Hume had was what he called matters of fact.
Matters of fact were claims that were based upon perceptions. I look outside my window
here, I see my car, and I see that it’s blue. I have a blue car sitting in the parking lot. But,
in fact, Hume said, we can never really be certain about those particular claims—not
ultimately certain about them. I can be certain about what my senses tell me, but I can’t
be certain that what my senses tell me is really true.
a. You might ask, “Why? Why can’t we be certain about that?” Hume basically said
this is because of the Egocentric Predicament. The Egocentric Predicament says,
basically, that I can only know what my senses tell me—that I, in fact, am locked
in to my own ego. I’m locked in to my own mind. How do I know that what I see
out there is really true out there? The only way I can know that is to get outside of
my own mind—to get outside of what my senses tell me—and check to see if it’s
really out there. But there’s no way I can get outside of my mind or what my
senses tell me. I have to, in fact, realize that what my mind tells me is all that I
have. I can’t find out about truth outside of my mind. Therefore I can’t be certain
that my car is really blue, ultimately, out there. I can only know what my senses
tell me, and that’s as far as I can know about that.
b. Also, Hume said, we make Universal Assumptions about things. We assume that a
lot of things are true in the world, and that you experience the world in the same
way I do. For example, when I see red, you’re seeing red as well. Or we assume
cause-and-effect. We assume these kinds of things, but in fact we have no real
way to test them to find out if they’re really true or not. I cannot know if the
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world outside my experience of it is really like that. All I can know is the world of
my experience. Therefore, Hume said, I can know nothing about reality beyond
my experience—what we might call “ultimate reality.” I can know what my
experience tells me, and I do have knowledge of that. But I can’t have knowledge
outside of what my experience tells me. I can’t have what we call “metaphysical
knowledge”—knowledge about the real world. Here’s a famous quote that
summarized Hume’s thought:
“When we run over libraries, persuaded of these principles, what havoc
must we make? If we take in our hand any volume of divinity or school
metaphysics, for instance, let us ask, Does it contain any abstract
reasoning concerning quantity or number? No. Does it contain any
experimental reasoning concerning matter of fact and existence? No.
Commit it then to the flames, for it can contain nothing but sophistry and
illusion.”
And Hume thought that many of the claims we make about ultimate reality, we can’t actually
know. We can only know what our senses tell us, and that’s about it. And he uses this principle to
deny all sorts of metaphysical claims. For example, take the concept of causality. You might
remember from an earlier presentation that when we examined causality, we saw that there were
three elements to it: contiguity, which means contact; priority, which means that causal event ‘A’
occurs before effect occurs ‘B’; and then, Hume said, this necessary connection, the relationship
between ‘A’ and ‘B’, whereas ‘A’ causes ‘B’. Hume says we can observe contiguity and we can
observe priority, but there is no way you can observe the necessary connection. Why? Because
relationships are not observable. I can’t really observe causality; I assume causality (that’s my
universal assumption). I assume that ‘A’ caused ‘B’. In my experience, I see ‘A’ and ‘B’
happening in that way. But I can’t actually observe the causality itself at all. Therefore, I can’t
really claim that I know about causality or causal effects. That was just one of the many truths
Hume said metaphysically we can’t really claim we know anything about at all. So Hume is a
great example of the local skeptic.
S5:
Well, how do we answer the skeptical challenge? What can we say to them? I think we can say a
couple of things.
1. First of all, there certainly is an impracticality to skepticism. No one can really live this
way. Can we really live our lives as if we don’t know anything at all? How about when
I’m driving through an intersection? I have to know whether the light is green or red
before I can proceed through the intersection. It seems to me I can sit here constantly
wondering, “Well, is it really green? Is it really red? How can I know that?” And I think
that is part of the problem: there’s just an impracticality to it.
2. Second of all, we do recognize that the nature of skeptical claims tend to be self-
defeating. We can certainly see that with the absolute skeptic. When he claims that “no
one knows anything, and I know that,” we immediately wonder, “wait a second—if no
one knows anything, how can you say that you know that?” How about the unmitigated
skeptic? Remember, he claims that no one knows anything, but he’s going to say, “I don’t
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know it, I just believe that it’s true.” Does he escape from this problem? I don’t think so. I
think ultimately it’s self-defeating for him too. We can ask the unmitigated skeptic, “Do
you know that you believe that no one knows anything?” He might step back and say, “I
don’t know that either. I just believe that I believe that no one knows anything.” But then
we can ask him again, “Do you know that you believe that you believe that you don’t
know anything?” And again he can step back if he wants. But then he runs into another
trap, which is the trap of having an infinite regress of knowledge claims. That kind of a
problem is very dubious. Infinite regresses of knowledge claims simply have nothing to
base anything on. And if you have beliefs and don’t have anything to base your beliefs
on, that calls into question the value of that belief. It’s a dubious belief.
3. But actually, I think the real problem with skepticism—the real way we can answer this
challenge—is to note that both Descartes and Hume were equating knowledge with
certainty. The question we might ask is, “Should that really be our goal?” Is that the only
kind of knowledge to have? Is certainty necessary in order to say that I know something?
I don’t think so. I think we can have a different goal rather than certainty when it comes
to knowledge. I would like to suggest the goal is defeasibility. Defeasibility says this: in
the absence of defeaters or the absence of the likelihood of defeaters, I am justified in
saying that I know something. In other words, a defeater is something that defeats my
claim to knowledge. I claim to know something, and someone comes along and says it’s
not true because he has evidence for it not being true. That would be a defeater. But in the
absence of those, in the absence of the likelihood of a defeater coming along, I think I am
justified in saying that I know something. So, for example, when I look out and see my
blue car in the parking lot, I think I am justified in saying that my blue car is out there in
the parking lot. Somebody could come along and say, “You know, it’s possible that
you’re wrong”—they could ask that question, “Do you think it’s possible that you’re
wrong?”—and I could say, “Yes, it’s possible that I could be wrong.” But is that really
enough of a defeater to defeat me? I don’t think so. I don’t think it is good enough to
simply assert that it’s possible that I’m wrong. You need to provide reasons—defeaters—
for why I should believe that I’m wrong. Why should I believe that what my senses tell
me isn’t really out there? They’ve been pretty reliable most of my life. I can depend upon
them pretty well, and, therefore, there’s no real reason to defeat them besides simply the
possibility that I could be wrong. The possibility of something is not good enough for
anything. As we all know, anything is possible besides a contradiction. Therefore, just
because something is possible doesn’t mean that it counts as evidence against something.
The question I want to ask is, “Is it probable?” Do we have good reasons to believe that?
And if there’s no good reason to question my knowledge—if there are no defeaters out
there—then I’m justified in saying I know something and I feel pretty good about that.
However, there is one thing I want to point out that I think is important to realize, and that is
skepticism does have a certain benefit to us. It has a lesson it does teach us.
One lesson that skepticism teaches us is the importance of epistemic humility. By epistemic
humility, I simply mean that we need to be careful about what we claim to know and what we
claim that we have as knowledge. We need to recognize that there are limitations to our cognitive
abilities—to our abilities to know things. And we need to be careful about overstating our case
about what we know. Sometimes we claim we know something, when in fact we really don’t
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have a good enough reason or enough evidence to be able to state that. We need to be careful. In
that sense, I think skepticism does teach us that we need to be careful about making claims about
certain knowledge when in fact we really don’t have certain knowledge.
I’ll tell you right now, I don’t think there are many things you can know with 100% for certain.
There are some, and we’ll mention some of those down the road. There are some things we can
know for certain, but most of our knowledge is based upon probability, upon what we observe.
There’s nothing wrong with that. Again, if your goal is defeasibility, I think there are good
reasons we have to believe most of the things that we believe are true. But certainty is a goal we
need to be careful about. I think we all can learn the lesson of epistemic humility that skepticism
teaches us.
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