To: Matthew M.
From: Geoffrey Klempner
Subject: Objections to Berkeley's theory of immaterial substance
Date: 4th February 2010 13:33

Dear Matthew,

Thank you for your email of 28 January, with your essay for the University of London Modern Philosophy: Descartes et. al. module, in response to the question, 'Berkeley's belief in immaterial substance faces the very objections he levels against the materialist's belief in material substance.' Discuss.

You have gone about this the right way. You've looked at the arguments which Berkeley deploys against material substance, and you have tried to see how they work, mutatis mutandis, against the idea of spiritual substance. It appears that you are prepared to defend Berkeley, on the grounds that his view of spiritual substance is derived from Descartes' cogito: our idea of the soul or spiritual substance is concrete because we perceive our own being as such.

I think you have missed something here. There are actually two lines of argument that I would deploy. The first, deriving from Hume, directly challenges the Cartesian claim. The second is more controversial, engaging with the idealist strategy of describing our experience without recourse to the notion of matter.

Here is a famous quote from David Hume, from Book I, Part 4, Section 6 of A Treatise of Human Nature:

'When I turn my reflection on myself, I never can perceive this self without some one or more perceptions; nor can I ever perceive any thing but the perceptions. Tis the composition of these, therefore, which forms the self. We can conceive a thinking being to have either many or few perceptions. Suppose the mind to be reduc'd even below the life of an oyster. Suppose it to have only one perception, as of thirst or hunger. Consider it in that situation. Do you conceive any thing but merely that perception? Have you any notion of self or substance? If not, the addition of other perceptions can never give you that notion.'

This looks to me like a direct challenge to Berkeley, using Berkeley's own strategy. When I look into my mind, I see my ideas but I don't see the spiritual substance in which those ideas inhere.

In 'Three Dialogues' one of the arguments Berkeley deploys against materialism is that we have no notion of how material 'causes' can produce material 'effects' -- echoing Hume's own destructive analysis of the naive idea of causation. Yet Berkeley contrasts this with the causation involved in willing an action. When I form the idea of moving my arm, which is followed by my experience of my arm moving, I am directly aware of the causal link between my desire or intention, and an event. Hume, of course, rejects this, for the same reason as he rejects the idea that we can 'see' causal links in the external world.

So, why do we need spiritual substance? Why do we need substance, period?

This question takes us into an examination of the coherence of Hume's radical empiricist philosophy. However, we can bypass Hume and just consider what are the minimal 'ingredients' for an idealist account of reality.

The idea of defining the world purely in terms of sense data was the project undertaken by phenomenalists, in the early part of the 20th century, under the general banner of 'logical positivism'. A.J. Ayer's earlier writings are a notable example, following the lead of Rudolph Carnap. The world can be completely described in terms of hypothetical statements about sense impressions. Selves are 'constructions' out of sense impressions, no less than the 'physical objects' that selves perceive.

The project failed. Berkeley had already put his finger on the weakest link: the idea that a subjunctive conditional statement, or rather a whole set of subjunctive conditional statements, can adequately stand proxy for a statement about the external world. For we are still left with the question of what it is, by virtue of which, the statement or statements in question is or are *true*.

For Berkeley, hypothetical statements about sense data or experiences are true
by virtue of how things are in a reality consisting of God and finite spirits.

The second of the two lines of argument which I mentioned earlier bears on idealism generally, as opposing account of reality to materialism (i.e. mental monism versus material monism).

It does seem very plausible that if one can give an account of your entire life in terms of your experiences, and hypothetical statements about those experiences, then the notion that there is 'something else' in reality is redundant: because you never get to see it, hear it, touch it.

However, there is an exactly parallel argument which is used by materialists, specifically Armstrong and Smart (so called 'Australian materialists') which goes as follows. A red sensation can be defined in physical terms as the state of an individual which renders that individual capable of, e.g., sorting out red tomatoes from green tomatoes. We don't know exactly how material bodies are able to perceive -- exactly how the brain processes visual data -- but we don't need this knowledge in order to state the materialist view: All statements about mental states and phenomena can, in principle, be given a 'topic-neutral analysis'.

Hence: 'If one can give an account of your entire life in terms of your physical movements and responses to the physical conditions in your environment, and hypothetical statements about your physical states, then the notion that there is 'something else' -- mental states -- is redundant, because it serves no function in a complete description of the material world.'

All the best,

Geoffrey