HCJ 2/3 – KANT

Against Hume- Rejection of the validity of induction

Experience can teach us that something is the case, but it can not show that it MUST be the case – Humes problem of induction.

Science does claim to discover necessary truths; but Hume says there are no necessary truths, and even more critically no causation except as a psychological misunderstanding.

Hume showed that people were irrational, the role of reason is only to define relations of ideas. 2 + 2 = 4, but that is only a tautology, and not about any tangible or necessary.

Kant objected to this ethically. It is essential that humans should be rational, so that they can be moral and free.

He is awoken for his dogmatic slumber (of Leibniz’s rationalism). He sets out to overturn Hume.

Humes a priori is just a matter of definition (All bachelors etc)

But theres a stronger version of a priori for Kant – someting that can be known completely independently of experience (synthetic a priori)

5,000 people on uni campus, who are alive take this as a true fact.

What further things can you deduce about the football stadium, with absolute certainty.

• you would know the minimum possible size of the campus.
• You would know that the temperature, atmosphere, etc, are such that they can support life
• you would know that time is elapsing at least from the subjective point of view of these 5,000 persons (assuming they are the same sort of beings as you – a crucial axiom for Kant)

These are facts about reality which are deduced from the a priori proposition, but without experience. And these truths are not merely analytic.

Note you have proved using synthetic a priori the existence of both space and time.

Try and imagine an object that does not occupy any space. This is impossible. Then category of space is a necessary precondition of perception, it is an iea that is necessary and UNIVERSAL – this is the pure a priori.

Same is true of time. We have no direct experience of time, but we have an ability subjectively to sequence events (this came before that). For us to be able to sequence events, then necessary and UNIVERSAL that there is time. Time (like space) is a necessary pre-condition for perception.

In fact, EXISTENCE IS A PRE-CONDITION OF PERCEPTION;

Existence is not a predicate (of perception), it is not the result of anything.

There is no “Cogito”, no mind perceiving non-contingent objects in a “Cartesian theatre”.

This is the “Copernican revolution” of philosophy. OBJECTIVE REALITY HAS TO CONFORM TO HUMAN APPARATUS OF PERCEPTION – the mind does not arise from objective reality; rather objective reality is created by the mind.

But there is not solipsism. The universe (and other people) does/do exist independently of one own mind. We can infer that other people are like us – using the synthetic a priori.

 

The argument goes like this:

1. The existence of the universe (and objects such as other people) exists as a necessary pre-condition of perception to my own existence.

2) I can infer from my own first person knowledge certain things about other people.

A) they occupy a certain space

1. They experience time, subjectively as I do (eg we can arrange to meet at a certain time)
2. They generally experience the same types of subjective experience as we – “cut me, I bleed” etc.

 

A priori we know that there is space-time; and this persists independently of perception (necessary and universal).

KANT: SPACE AND TIME ARE THE PRE-CONDITIONS OF ALL EXPERIENCE (these things are not the result of perception).

Main categories	analytic	synthetic	pure
A priori (Hume – ROI) Necessary, universal – to deny/ break the law of non-contradiction.	All bachelors are unmarried	Cause and effect The self exists Persistence of unobserved objects Fire causes pain 2+1=3 (Possible for Kant, but not for Hume)	Objects exist in space and time
A posteriori (Hume – MOF) Contingent, situational	(not possible for Kant or Hume or anyone else)	Some bachelors are bald; Drinking causes intoxication; Some objects are Some types of cheese taste tangy; others bland	Raw sense data; dissociated perception (“sensations” – Hume)

PHENOMENA AND NOUMENA

The Copernican revolution in philosophy.

“we see the world in terms of space and time because we wear space-time goggles” – Bertrand Russell’s summary of Kant.

“every chance requires a cause” – is a priori, but contrary to Hume it is not simply a relation of ideas, it requires JUDGEMENT which is necessary and universal, and known as first person, subjectively.

Kant “saves” science and metaphysics from Humes skepticism by restoring cause and effect to nature, via the synthetic apriori.

Observations such as “every change has a cause” is necessary and can be known a priori, subjectively.

Observations such as “all bodies are heavy” is only a generalization of aposteriori experience, and could be falsified without denying THE TRANSCENDENTAL UNITY OF PERCEPTION (OR MIND).

“Unity of perception” means that individual thoughts and sense date are synthesised into a whole picture. Like Descartes Kant discusses dreams; the subject experience in a dream state of consciousness.