Philosophical Battles: Empiricism versus Rationalism
The history of philosophy has seen many warring camps fighting battles over some major
issue or other. One of the major battles historically has been over the foundations of all our
knowledge. What is most basic in any human set of beliefs? What are our ultimate starting
points for any world view? Where does human knowledge ultimately come from?
Empiricists have always claimed that sense experience is the ultimate starting point for all
our knowledge. The senses, they maintain, give us all our raw data about the world, and
without this raw material, there would be no knowledge at all. Perception starts a process,
and from this process come all our beliefs. In its purest form, empiricism holds that sense
experience alone gives birth to all our beliefs and all our knowledge. A classic example of an
empiricist is the British philosopher John Locke (1632–1704).
It's easy to see how empiricism has been able to win over many converts. Think about it for
a second. It's interestingly difficult to identify a single belief that you have that didn't come
your way by means of some sense experience — sight, hearing, touch, smell, or taste. It's
natural, then, to come to believe that the senses are the sole source and ultimate grounding
of belief.
But not all philosophers have been convinced that the senses fly solo when it comes to
producing belief. We seem to have some beliefs that cannot be read off sense experience,
or proved from any perception that we might be able to have. Because of this, there
historically has been a warring camp of philosophers who give a different answer to the
question of where our beliefs ultimately do, or should, come from.
Rationalists have claimed that the ultimate starting point for all knowledge is not the senses
but reason. They maintain that without prior categories and principles supplied by reason,
we couldn't organize and interpret our sense experience in any way. We would be faced
with just one huge, undifferentiated, kaleidoscopic whirl of sensation, signifying nothing.
Rationalism in its purest form goes so far as to hold that all our rational beliefs, and the
entirety of human knowledge, consists in first principles and innate concepts (concepts that
we are just born having) that are somehow generated and certified by reason, along with
anything logically deducible from these first principles.
How can reason supply any mental category or first principle at all? Some rationalists have
claimed that we are born with several fundamental concepts or categories in our minds
ready for use. These give us what the rationalists call "innate knowledge." Examples might
be certain categories of space, of time, and of cause and effect.
We naturally think in terms of cause and effect. And this helps organize our experience of
the world. We think of ourselves as seeing some things cause other things to happen, but in
terms of our raw sense experience, we just see certain things happen before other things,
and remember having seen such before-and-after sequences at earlier times. For example, a
rock hits a window, and then the window breaks. We don't see a third thing called
causation. But we believe it has happened. The rock hitting the window caused it to break.
But this is not experienced like the flight of the rock or the shattering of the glass.
Experience does not seem to force the concept of causation on us. We just use it to
interpret what we experience. Cause and effect are categories that could never be read out
of our experience and must therefore be brought to that experience by our prior mental
disposition to attribute such a connection. This is the rationalist perspective.
Rationalist philosophers have claimed that at the foundations of our knowledge are
propositions that are self-evident, or self-evidently true. A self-evident proposition has the
strange property of being such that, on merely understanding what it says, and without any
further checking or special evidence of any kind, we can just intellectually "see" that it is
true. Examples might be such propositions as:


Any surface that is red is colored.
If A is greater than B, and B is greater than C, then A is greater than C.
The claim is that, once these statements are understood, it takes no further sense
experience whatsoever to see that they are true.
Descartes was a thinker who used skeptical doubt as a prelude to constructing a rationalist
philosophy. He was convinced that all our beliefs that are founded on the experience of the
external senses could be called into doubt, but that with certain self-evident beliefs, like "I
am thinking," there is no room for creating and sustaining a reasonable doubt. Descartes
then tried to find enough other first principles utterly immune to rational doubt that he
could provide an indubitable, rational basis for all other legitimate beliefs.
Philosophers do not believe that Descartes succeeded. But it was worth a try. Rationalism
has remained a seductive idea for individuals attracted to mathematics and to the beauties
of unified theory, but it has never been made to work as a practical matter.
PRO EMPIRICISM
Empiricism is Simpler: Compared to Empiricism, Rationalism has one more entity that
exists: Innate knowledge. According to the Empiricist, the innate knowledge is
unobservable and inefficacious; that is, it does not do anything. The knowledge may
sit there, never being used. Using Ockham’s Razor (= when deciding between
competing theories that explain the same phenomena, the simpler theory is better),
Empiricism is the better theory.
Colors: How would you know what the color blue looks like if you were born blind? The
only way to come to have the idea of blue is to experience it with your senses. (This
objection only works possibly against Plato; see the introduction above again to see
why this objection would not faze Descartes, Leibniz, or Chomsky.)
Imagination and Experience: How can we get the idea of perfect triangularity? We can
extrapolate from our experience with crooked, sensible triangles and use our
imagination to straighten out what is crooked and see what perfect triangularity is.
Rationalists have been Wrong about Their “Innate Knowledge”: Some medieval
rationalists claimed that the notion of a vacuum was rationally absurd and hence it was
impossible for one to exist. However, we have shown that it is possible. Reason is not
the only way to discover the truth about a matter.
The Advance of Science: Much of science is founded on empiricist principles, and would
not have advanced without it. If we base our conclusions about the world on
empiricism, we can change our theories and improve upon them and see our
mistakes. A rationalist seems to have to say that we’ve discovered innate knowledge
and then be embarrassed if they’re ever wrong (see examples such as the vacuum,
above).
All Rationalists do Not Agree about Innate Knowledge: Rationalists claim that there is
innate knowledge that gives us fundamental truths about reality, but even among
rationalists (e.g., Plato, who believes in reincarnation and Forms and Descartes, who
does not believe in either but does believe in a soul), there is disagreement about the
nature of reality, the self, etc. How can this be, if there is innate knowledge of these
things?
PRO RATIONALISM
Maths and Logic are Innate: Doesn’t it seem that mathematical and logical truths are true
not because of our five senses, but because of reason’s ability to connect ideas?
Morality is Innate: How do we get a sense of what right and wrong are with our five
senses? Since we cannot experience things like justice, human rights, moral duties,
moral good and evil with our five senses, what can the empiricist’s ethical theory
like? Hume (an empiricist) says morality is based solely on emotions; Locke says
experience can provide us with data to show what is morally right and wrong, but does
it seem that way to you?
Verifying Empiricism: Locke (an empiricist) says that our experiences tell us about the
nature of reality, but how can we ever check our experience with what reality really is,
in order to know that? Rationalists do not think we can, so we have to rely on reason.
Poverty of Stimulus Problem: Three year olds use language in ways that they are not
explicitly taught. For example, they form original sentences from words that they
haven’t heard put together in precisely that way before. Also, they start to understand
grammatical rules before they even know what a noun or a verb is. If we can only say
what we’ve heard said by others, how can three year olds speak as well as they
do? This is known as the poverty of stimulus problem. You may think that Rationalism
is strange, but it does a better job of explaining this problem than Empiricism. One way
of choosing which of two theories is better is asking, “Which theory explains the
phenomena better?”
Empiricism Undermines Creativity? According to Empiricism, you can combine things,
separate them, and nothing else. With Rationalism, we come to experience with readymade tools for creativity. E.g., Plato would say that we’re in touch with abstract,
immutable realities, which provide lots of material with which to create.
Controllable Humans? According to Empiricism, human beings can exceptionally be
controlled and manipulated easily. If we are nothing other than what we experience,
then we should be able to be made to do whatever we’re taught. Rationalism has it
that there is an invariable core (call it “human nature”) that refuses to be manipulated,
which is what makes us unique.