Rationalism and Empiricism
Knowledge based on reason, such as mathematical truths (e.g. 2+2=4) can be said to be
absolutely true. They are true by definition. Philosophers refer to these truths as rational
or a priori truths, meaning that they are true prior to experience. These statements can
take the form of two equal sides, like an equation, or the statement "A spinster is female
and unmarried". They may also take the form of describing properties of a definable or
theoretic concept, such as 'all triangles have three sides'. It is significant that we could
not say this of something we encounter in the world. We could not say 'All spinsters have
curly hair' and know it to be true without experience. Thus, because we can know rational
truths without having to experience the world, then by definition they can tells us nothing
about the world as we experience it. The source of rational knowledge is independent of
experience, as these truths remain equally true whether an individual is aware of them or
not. However, we know that we do learn by experience, and as such experience is
another source of knowledge. However, experience is a less reliable teacher as we can
always imagine these statements to be false. Philosophers call these statements empirical
or a posteriori truths, meaning true after experience. We could imagine that cats were
normally green, or the sun would not come up tomorrow; experience might tells us that
this is not the case, but we know that it is possible for new experience to disprove the old
(for example, if you moved to the dark side of the moon and the sun didn't come up).
These, then are our two sources of knowledge: rationalism and empiricism, but
which is the stronger source for knowledge?
Knowing rational truths gives us reliability and certainty. We can expand rational truths
and use them as tools, for example if we know A=B, and B=C, then we necessarily know
that A=C. However, because these truths tell us nothing about the world in which we live,
then they are of little relevance in day to day living. They have little utility in helping us
to do things, such as crossing the road safely or building a shed. In addition, there is
relatively little that we can know based upon pure reason alone. As a source of
knowledge the strength of rational statements lies in reliability and predictability, but not
in breadth or applicability. However, when we look not just at single rational statements,
but at rational arguments (such as 'All men are tall, Fred is a man, therefore Fred is tall')
we can see that the logic is useful. Yet, if the premises ('All men are tall, Fred is a man')
are not true then although the argument is rational and logical, it remains false.
Experience allows us to test the truth of logical arguments. Experience allows us to
survive, acquire skills and to hone those skills as we gain more and more experience in
using them. However, whilst experience has great utility, it does not seem to adequately
explain the scale of human knowledge compared to other beings that experience the
world, for example animals.
How then, do humans gain knowledge? Is it solely from some rational truths we are born
with and the rest we learn through experience? Consider a child learning to speak. A
young child can utter a sentence they have never heard before once they have learnt the
words and how they fit together. An adult with a basic vocabulary can create more
sentences than can be spoken in a lifetime, they are not copying a sentence they have
heard or read, so how can they have learnt solely by experience? The key is the
interaction between the two sources of knowledge. In language we need not only to know
the words of the language, but how they fit together to provide meaning. This involves
knowing the structure and rules of the language and not just the words within it (for
example it is not possible to learn a language simply by studying a dictionary). By
understanding or deducing the underlying principles of the language (the logical, rational
part) as well as the words (the experienced part), anyone can create a sentence they
have never heard before. Their rational knowledge will provide the structure, their
empirical knowledge the content.
We know that if A=B and B=C then A=C. By applying rationalism to experience, humans
can make logical leaps. For example if my experience tells me that A=B, and also that B
is similar to C then I might reasonably surmise that A is also similar to C. From a rational
perspective this is not totally valid, as A, B, and C are not all exactly equal. However, in
the empirical world it is possible to test this and thus learn from it.
In this way it is possible to use empirical knowledge and predict what other experiences
might be like. Although we are using empirical knowledge, we are performing a rational
operation on it. We are using logical extrapolation of experience to understand things
before we have experienced them (in this way it can be said to be a priori). This is
fundamental to the workings of the human brain. Human thought patterns allow us to
conceptualise. A child can easily understand the relationship between the word 'bee' and
what they experience as a 'bee'. Thus we can manipulate the concept of 'bee' in our
minds when we are not experiencing a bee. This allows us to perform logical operations
on our empirical knowledge and in doing so arrive at potentially new knowledge.
This is the approach taken in science. The scientific method involves making a logical
prediction based upon previous. We do not know that it is true, but we can test this
hypothesis with further experience. In order to record and communicate this experience
logical systems or mathematical models are used to describe the experience, for example
by applying a mathematical formula to match the results of an experiment.
This shows us that by applying rational and logical methods to experience we can
accelerate the acquisition of empirical knowledge. As we can communicate logical
concepts via our structured language we can give people some knowledge of something
when they may not have experienced it first-hand. For example, you may not have
experienced a ride in a rocket, but you could gain some understanding of this by listening
to someone who explained his or her experience. This is not strictly a priori, as you have
had some experience (the explanation) of the rocket ride, but you do not need to have
first-hand experience of the rocket ride to have some knowledge of what it may be like.
Thus, it is possible to gain more empirical knowledge than simply that from your own
direct experiences.
We cannot imagine having no experience. The existence of an individual necessarily
implies that that person has experience, even if their senses are deprived. Assuming that
someone with no experience could exist, then we could say that they had no knowledge.
In fact, we could go further and say that were not alive as all life reacts to its
environment, by definition, and to react you must therefore be able to perceive. We know
that rational knowledge exists before experience, so if to exist is to experience we must
always have both sources of knowledge.
Therefore, we can conclude that neither reason nor experience is the stronger source for
knowledge, and that although knowledge may come from either source, they are
inextricably linked in the acquisition, storing, manipulation and use of that knowledge.
Full knowledge comprises both rational and empirical knowledge and thus is not whole
without both of its parts.