Philosophical
Bits #2:
Skepticism
But how do I know “this is
real”? Epistemology tries to answer the
question: How do I know? Related
questions: What is knowledge? What
distinguishes knowledge from mere belief, even true belief?
Everyone agrees we would rather have
true beliefs than false beliefs. But a
true belief is not the same thing as knowledge.
In the Meno, Socrates points out that some people may adopt a
belief, a belief which turns out to be true, without good evidence or by bad
reasoning. They might believe something
merely because their hated enemy doesn’t believe it or because no one has
proved it false. They might fall into a
belief by accident. Mere true belief is
not enough, says Socrates. We know
when the truth of our belief is tied to the belief by the “bonds” of good
reasons.
This traditional answer, that
knowledge is justified true belief, received scrutiny in the 20th
century. In 1963 Edmund Gettier
published a short article, “Is Justified True Belief Knowledge?” in which he
gives examples of persons who believe a proposition for good reasons (so the
belief is justified), and the proposition is in fact true, but do not seem to
be cases of knowledge. Other
philosophers quickly created more examples.
Here’s one: While driving in the Willamette Valley, Debbie sees what
looks to be a sheep and forms the belief, “There is a sheep in that
field.” In fact, the animal she sees is
a dog wearing a sheep outfit made by a middle-school student as part of a
prank. However, unknown to Debbie, there
is another animal, a real sheep, standing in a portion of the field but hidden
from her sight by a large sign. Debbie’s
belief is true (there really is a sheep in the field), and her belief is
justified (she sees an animal that looks like a sheep), but it seems that her
justified belief is true only by accident.
It seems her justified true belief isn’t knowledge.
Philosophers have tried to repair
their understanding of knowledge in a variety of ways. I won’t discuss the details. In general, the answer to Gettier problems is
that justification must hook up to the true belief in the right way. But the devil is in the details. What is the right way? Disagreement persists on that score.
Skeptics watch from the
epistemological sidelines, as it were. The
players in the epistemology game strive to define knowledge, with the goal of
better guiding our pursuit of knowledge.
The game is pointless, say the skeptics.
Knowledge is a chimera.
Epistemology might produce some guidance about the way we adopt or
reject beliefs, but we should abandon the hope of attaining knowledge. Regarding any particular belief, the skeptics
say, we must face the truth: we might be wrong.
What about science? Four centuries of modern science have
dramatically changed our beliefs.
Technology, based on scientific discoveries, has dramatically changed
our practical world in thousands of ways: electricity, telephones, antibiotics,
plastics, radio, Internet, blood transfusions, cars, telescopes, airplanes,
microscopes, genetic tests, photographs, videos, recorded music, man-made
fibers, and so on. Surely science gives
us knowledge, and the knowledge given by science has made technology possible.
The skeptics say no. Science gives us new beliefs. Technology based on those beliefs has changed
our practices. But are we guaranteed those
beliefs are true? Do we have knowledge? No. We
might be wrong.
20th century skeptics
were certainly aware of modern science. The
scientific method combines empirical observations with theories. We propose the theories to make sense of the
observations, and we use further observations to test the theories. Therefore, some philosophers said (these
philosophers identified themselves as “positivists”), empirical observations
must lie at the heart of science.
Scientific and philosophical theories are meaningless, the positivists
said, unless they can be verified empirically.
A.J. Ayer’s 1936 book, Language, Truth, and Logic is an
enthusiastic presentation of positivism by one of its exponents. According to Ayer’s “verification principle,”
all meaningful statements are either tautologous or verifiable (at least in
principle).
Now, the verification principle is
self-referentially incoherent. It is
itself neither tautologous nor verifiable.
In the second half of the 20th century, philosophers rejected
it. Along the way, though, positivism
taught an important lesson.
Positivism inspired a conceptual
search for pure empiricism, empirical observations untainted by theory. What would an “observation statement” look
like? Obviously, if you use a scientific
instrument like a telescope, all your observations must be qualified; you
didn’t simply look at the stars, you looked at them with this instrument, with
a specific description, and that description implicitly drags in a host of
assumptions about light, mirrors, the construction of the telescope, and many
other things. And in everyday scientific
practice, that’s fine. But if scientific
theories are to be tested by observations, at bottom we need some observations
that are theory-free. What would “pure”
observation be like?
For a decade or two, in the middle
of the century, positivist philosophers of science tried to conceptualize
theory-free observations. By the time
positivism collapsed (because of its self-referential incoherence), philosophers
of science had adopted a truism: there are no theory-free observations. All our empirical observations are
loaded with assumptions.
Does this mean we don’t have
knowledge? Are the skeptics right?
For example, can we know that
everyday empirical experiences yield truth?
Is the grass really green? (Fido
doesn’t see color. Is color real?) Is there a tree over there? Should I modestly say only that it seems
to me that there is a tree over there?
Some skeptics would say I know only that it looks like a tree to me; the
world outside my mind may be different than what I perceive.
Can we know that other people have minds? I might know that I have a mind, by direct
experience. But can I know that other
people have minds, that they are not cleverly designed robots? The skeptics would say we can’t know these
things. After all, maybe the world was
created five minutes ago by an evil demon who made the world just to deceive
me. For all I know, the whole world is
just a figment of my imagination, and everything other than my mind is nothing
more than an item in my mental universe.
Against the skeptics, G.E. Moore published a paper in 1939, “Proof of an
External World.” In a public reading of
the paper, Moore held up his hand. “I
know this is a hand,” he said. “And here
is another.” Since Moore and his
audience both know these two things, there must be a world external to their
minds.
It is said, perhaps apocryphally,
that Ludwig Wittgenstein told Moore this paper was the best thing Moore had
written. Wittgenstein certainly wrestled
with the problem. A collection of his
notes, written in the last months of his life and called On Certainty,
begins: “If you really do know ‘Here is one hand,’ we’ll grant you all the
rest.”
On Certainty is not a
polished book, but a collection of notes, published after Wittgenstein’s death
in 1951 by his literary executors.
Philosophers have struggled with it ever since. My own notes on On Certainty are
almost as long as On Certainty.
Wittgenstein thought something had
gone wrong on both sides. The skeptics
want to say we don’t know everyday facts that we observe or remember. Moore wanted to insist that he did know he
had two hands, and his audience knew this as well. Wittgenstein thought both sides had lost
touch with the “language game” of knowing.
The meaning of language is in its
use, Wittgenstein wrote in Philosophical Investigations. How do ordinary people talk about knowledge
when they are not wrestling with skepticism?
When would we, in real life, say, “This is a hand”? The language game of knowing includes things
like doubting and being sure.
Example. Bob asks, “Did you go to the club
Thursday?” Sally replies, “Sure. I always go.”
Bob: “But they moved the meeting last week.” Sally: “Oh! That’s right. I forgot.
I went to the meeting Wednesday.
But I also went to the club Thursday.
I know I did because I had to return a book.”
This is an unremarkable use of
“know,” completely at home in ordinary language. Both the skeptic and the commonsense realist
(Moore) are tempted to take knowing away from such examples. I think Wittgenstein praised Moore’s essay
because “Proof of an External World” shows how the skeptics had gone too
far. But he worried that Moore’s
refutation—“I know this is a hand”—was also language gone on holiday.
Perhaps the best answer to
skepticism is that we live this way.
We live in a world where water boils at 100 degrees Celsius and freezes
at 0 (an example in Wittgenstein’s notebook).
We are confident that the world of my morning walks is real, but the
world of my novel is not. We cannot “refute”
the extreme skeptic, but we live this way. And the skeptic is one of us.