Sandra asked:

How is Kant's philosophy a synthesis of Rationalism and Empiricism?

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Descartes held that we have 'innate ideas' planted in our minds by God. Locke said that all human
knowledge comes from experience: the infant's mind at birth islike a blank sheet waiting for
knowledge to be written on it - a tabula rasa.The rationalists Spinoza and Leibniz agreed with
Descartes, the empiricists Berkeley and Hume agreed with Locke.

So the story goes.

A keen student will be quick to point out that the empiricists couldn'thave held that the mind lacked
any innate powers.And what is an 'idea', a 'concept' but a power to organize perceptions in a
particular way? So what was the dispute really about? and what was Kant's contribution to the
debate?

There are just three concepts that we need to think about: the concept of oneself,the concept of
things occupying spaceand the concept of a cause.How are we able, from a barrage of
uninterpreted sensations, to identify ourself as the subject or owner of those experiences? How do we
succeed in sticking our experiences together to make things that occupy space and persist through
time? Where do we get the idea of one thing causing something else to happen?

Kant agreed with the empiricists that there is no rational faculty that enables me to perceive the
innate ideas inside my own mind, as Descartes thought he could perceive his own soul and his idea
of God. David Hume, in response to Descartes' claim about the soul reported that,

For my part, when I enter most intimately into what I call myself,I always stumble on some particular
perception or other, of heat or cold, light or shade, love or hatred, pain or pleasure. I never can catch
myselfat any time without a perception, and never can observe any thing but the perception.
Treatise on Human NatureBook I, Part IV, Sec vi.

When philosophers' intuitions clash like this it's the end of the debate. Kant took the side of the
empiricists in absolutely rejecting anyspeculations about what God mighthave planted in the human
mind, that cannot be established by means of a logically compelling proof.

...in this kind of investigation it is in no wise permissible to hold opinions.Everything, therefore, which
bears any manner of resemblance to an hypothesis is to be treated as contraband; it is not to be put
up for sale even at the lowest price, but forthwith confiscated, immediately upon detection.
Critique of Pure ReasonPreface to First Edition, A xv.

Yet Kant also believed - and this is where he found himself on the side of the rationalists - that if the
innate powers of the mind were not specifically targeted on forming a concept of self, identifying
things in space and their causal relations, then the infant would never get to first base. It could never
succeed in making sense of its experiences.

Kant thought he had found the proof. He called it, rather grandly, his Transcendental Deduction of the
Categories.It is the centrepiece of the Critique.- It is also incredibly badly written, obfuscating and
repetitious. The essential core of the argument, without which the whole thing falls to pieces, is
tacked on as an afterthought in the 'Refutation of Idealism' of the Second Edition.

For what it's worth, this is my interpretation how the argument goes:

1. I have experience.No-one could doubt that, could they?

2. Having experience means my remembering experiences I have had before, along with being
   aware of the experiences I am having now.You need a moment to think about this, to see why it's
   true.

3. The two 'I's, and 'my' in the previous statement all refer to the same subject I.Need to think
   about this too. If the present 'I' seemsto remember experiences which someone else had rather than
   me, then my memory claim is false. Kant calls this feature the 'transcendental unity of apperception'.

4. I have to conceive of myself as being located ina world which my experiences are of,
   meeting up with objects I have met up with before.Now we are getting to the crux. Note that this
   isn't yet the world as we know it. You could think of the 'objects' of experience as just strung along in
   a line, like a melody that can be played forwards or backwards.

5. Objects which I perceive, then meet up with later, must be conceived as continuing to exist
   meanwhile.Not true of the melody.

6. Objects which continue to exist must have a placeto exist in.This is where the categories of
   substanceand a spatial worldcome in.

7. If things have changed when I get back to them, there must be a way of knowing whether
   they really have changed, or whether my memory is wrong. Changes happen in the world
   predictably, as the result of other changes happening.This is where the category of causecomes
   in.

So the mere fact that I have experience provesthat the concepts of substance and cause can't be
constructed out of my experience but must be - innate. An amazing result, don't you think?

Geoffrey Klempner