To: John D.
From: Geoffrey Klempner
Subject: Idealism and the nature of metaphysics
Date: 4 July 2007 12:48

Dear John,

Thank you for your email of 26 June, with your essay for the Metaphysics program in response to the question, 'What is Metaphysics? Is there anything special about the methods of metaphysics, or about its subject matter? Illustrate your answer with one example of a metaphysical problem or controversy.'

This is an engaging piece which shows that you feel gripped by the grand project of metaphysics and its promise to give a deeper insight into the nature of reality than empirical science can provide.

You have chosen as your example the controversy over idealism, and in particularly the immaterialism of Berkeley and the transcendental idealism of Kant.

Let's look at Berkeley first.

The first question to ask is, what, according to Berkeley is a 'sheer illusion'? It is not sheer illusion that I am tapping the keys of my computer keyboard, or that it is cloudy outside, or that I was born in 1951, or that the Earth is the third planet from the sun. All these are true, for the Berkeleian idealist as much as for the materialist (thinking or otherwise).

In the language of unit 1, these are 'mundane' facts. The adoption of a metaphysic is, or ought to be, indifferent to mundane facts. That is why a metaphysical theory cannot be empirically confirmed or refuted.

Berkeley, rather ironically - or cheekily - claimed that he was defending common sense. How could that be?

The 'illusion' in question for Berkeley is a philosophical illusion, a false or incoherent philosophical theory. He would emphatically reject your criticism, 'in order to reject something, we must have some idea of what we're rejecting'. We reject the concept of 'witch' because we do not believe what the witch hunters believed, that there is such a thing as 'witchcraft', although there are men and women who call themselves 'witches'. Scientists reject the concept of 'phlogiston' for empirical reasons (e.g. Lavoisier's famous experiment with mercury). In both cases, we can say that there might have been witches, or if the laws of nature had been different, there might have been such a thing as phlogiston.

By contrast with these examples, Berkeley rejects 'matter' because, according to him, the notion of 'matter' is incoherent. We think we know what we are talking about when we talk of 'matter' but it turns out that we are just talking nonsense.

In arguing against matter, Berkeley took Descartes' speculation about the possibility of an evil demon who deceives us into thinking that there exists a world of objects in space outside our minds, and asked a very simple but devastating question: what difference would it make if now and forever more experience 'as of' an external world will be reliably produced in us by some unknown external agency? Assuming that a benevolent God would never deceive us, what can he actually DO to bring into existence a world of material objects in space corresponding to our experience? The Earth is the third planet from the sun on either view. The earth and the sun 'exist' on either view. Berkeley concludes that philosopher's talk of 'matter' is logically redundant. Or, as Wittgenstein would put it, 'a wheel which can be turned, although nothing turns with it, is not part of the mechanism'.

This kind of argument is one that you will come across repeatedly in metaphysics. In effect (as Wittgenstein noted) it is a version of Occam's Razor which, unlike the application of Occam's Razor to empirical theories where we are seeking the 'best explanation', depends on the principle that in order to have meaning, a concept must 'do work', it must have a valid role to play in our conceptual scheme.

It is true, of course, that Berkeley needs a sufficiently powerful concept to replace 'matter'. When we look out at the world, we are looking at the inside of God's mind. Why choose 'God' over 'matter'? Simply because God is defined in terms of something we are already given, namely subjectivity. God is the infinite subject, while we are finite subjects.

There is considerable room for debate over the question just how far Kant succeeded in distancing himself from Berkeley. He was stung by criticisms of the first edition of the Critique of Pure Reason into producing an additional argument, his 'Refutation of Idealism' (which will be discussed in unit 4). However, arguably, all Kant succeeds in doing is explain why our experience must take the form that it takes, of being 'as of' an external world of objects in space. Berkeley could happily agree to that.

Where Berkeley and Kant finally disagree is over what ultimately exists, in virtue of which we exist as subjects whose experience is 'as of' an external world. Attending more closely to the limits of meaning than Berkeley, Kant insists that there is nothing intelligible that can be said about the ultimate reality, or the world of 'things in themselves' which he calls 'noumena'. Noumena represent the far side of the limit of human understanding and reason.

In Kant's theory of the phenomenal world, space and time are a priori 'forms of sensibility' (not 'sensations') while the principles of causality and the permanence of substance are a priori principles which account for the possibility of experience. To repeat, there is nothing here with which Berkeley need disagree. It is only when Kant turns his attention to what exists beyond the world of phenomena that we find a sharp division of views.

All the best,

Geoffrey