To: Natasha G.
From: Geoffrey Klempner
Subject: Can the solipsist be refuted?
Date: 20 May 2003 11:43

Dear Natasha,

Thank you for your e-mail of 8 May, with your fifth and final essay for the Philosophy of Mind program, in response to the question, "''The world is my world.' - Explain how the theory of Solipsism arises in the context of the Mind-Body Problem. Can the Solipsist be refuted?"

You have given a very clear characterization of solipsism. However, more needs to be said about how solipsism arises in the context of Descartes solution to the mind-body problem.

Descartes states, in Meditation 1, that his aim, in seeking to 'doubt everything' is to provide knowledge with an unshakeable foundation. Later in the Meditations, he uses the result of this exercise in his argument for mind-body dualism.

One part of the foundation is immediate experience, how things seem at this moment in time to myself, to the subject making the judgement. The other part of this foundation is the conviction (which Descartes tries to back up with proof) that not only is there *something* which gives rise to experience which is not just more of the same, but that this something is connected to experience in a reliable way, so that experience can be trusted as a guide to how things are in the external world. Hence the idea of a God who would not deceive me.

Descartes never in fact considers radical solipsism, of the kind we are considering, as a serious possibility. If you look at what he says in Meditation 1, he never doubts that there is *something* outside experience which causes experience. The problem is that this might be an evil demon who uses this power to deceive me, rather than a God who can be relied on not to deceive me.

However, we can be more radical than Descartes and raise the question why there has to be a 'cause' of my experience. Why can't everything just be my experience?

You say, 'The Solipsist needs some sort of private language in order for his theory to be confirmed'. The issue is not so much with confirmation of a theory (because according to solipsist, there is no other possible theory, no competitor to solipsism) but rather with the possibility of *stating* the solipsist theory.

The solipsist wants to be able to make the metaphysical statement, 'The world is my world', as well as being able to make empirical (non-metaphysical) statements like, 'I am now eating a sandwich', 'The sun has just come up' and so on, which he/ she re-interprets in terms of the solipsist theory.

In attacking the solipsist, it is not enough to say, 'But you don't have anyone to talk to because according to solipsism you are all alone.' There is no point in my talking aloud at this moment because there is no-one to hear me. But that does not prevent me from making sense.

The aim of using the private language argument against the solipsist is to show that the conditions necessary for words to have meaning cannot obtain in the solipsist's world. I think that it is possible by this means to prove that solipsism is internally incoherent.

By coincidence, this morning I answered an e-mail from Mike, one of my students taking the Philosophy of Language program who had raised a question about solipsism (Wittgenstein puts forward a version of solipsism in his early work, 'Tractatus Logico-Philosophicus'.) This is what I wrote:

"The solipsist is committed to finding an absolute epistemological foundation for truth and meaning in whatever is available to the first person perspective only. This leads to incoherence, because *there is no experience which guarantees its own interpretation*. There is always room for more than one judgement - more than one way to apply the rules, indeed more than one set of rules - given *any* amount of experience."

- The difficulty with saying this is that if we say that in addition to a first person perspective there is also a third person perspective, why doesn't that simply reduplicate the problem? Suppose I say that I am not a solipsist because I believe that you really exist, and you say that you are not a solipsist because you believe that I really exist. So now we have two subjects and their experiences instead of one. Why does that make things any better? How does that get you, or me off the hook? Suppose we agree that other people besides us exist? Why does that make any difference?

It seems that one say the very same thing as before, substituting 'we' for 'I' - "There is always more than one way to apply the rules...given any amount of experience."

To prevent this consequence, we cannot allow our confidence that our words have meaning to be undermined by the doubts which were legitimate in the case of solipsism. Wittgenstein, in his later work 'Philosophical Investigations' makes clear that he rejects the idea of seeking an absolute foundation for knowledge in the Cartesian sense. So when he says that 'following a rule is a practice', or that public language does not derive its meaning from a private language, he is not simply replacing 'my experience' with 'our experience'.

As this letter, and also my letter to Mike has reminded me, after thinking about these things for quite a while now, I still do not feel that I *fully* grasp what is going on here. However, I remain convinced that the question of solipsism and how to refute it is one of the most important pivot points in philosophy.

All the best,

Geoffrey