11 August 1997
Thank you for your letter of 4 August. I suppose in urging you to 'consider the challenge' of solipsism I more or less deserved your impatient response! How can I make a case for taking this kind of problem seriously?
First, what is it to take a problem 'seriously' in philosophy? I am not thinking of the angst-ridden teenager quaking at the thought that solipsism just might be true, or the philosophy student leading a secret life as a murderous psychopath who has come to the conclusion (worrying indeed for us) that it is true. You and I know solipsism is false. That's great: I believe in you and you believe in me.
Or, on second thoughts, not so great. For the solipsist's worry isn't analogous, say, to the worry that the letters and course units which I send to 'Margaret' are actually being fed to a giant computer the philosophic equivalent of Deeper Blue (Kasparov's victorious 'opponent').
That worry, it might be argued, is factual not metaphysical. However, one could easily turn the factual worry into a full-blown sceptical hypothesis of the 'evil demon' variety: then we're onto the 'challenge of global scepticism' (where exactly the same considerations apply with regard to 'taking the problem seriously' as apply in the case of solipsism).
One aspect of the challenge is to grasp what claim the solipsist is making, and how that differs from scepticism. 'So what?', you might say. I would argue that the falsity of solipsism lies at the heart of the truth of another metaphysical theory, the theory that you and I believe in or at least say we believe in.
The challenge is to understand that theory, to grasp what exactly it claims and also to grasp the logical reasons why what it claims is indeed true (sc. that solipsism is false). This is what philosophers do. Bradley defines metaphysics as 'The finding of bad reasons for what we believe on instinct; but to search for those reasons is no less an instinct'. (That may not be an exact quote: I don't have Appearance and Reality with me.) I don't necessarily go along with the 'bad' bit, but I find myself broadly in agreement.
Getting onto scepticism and Berkeley, though sometimes you will find the text books treating Berkeley as an easy target, I am unimpressed by their knock-down 'refutations'. Berkeley may use confusing terminology at times, but his basic argument and his metaphysical vision are a lot stronger than many give him credit for. But is this scepticism? No! Refuting Berkeley's immaterialist metaphysic is a different matter from refuting sceptical hypotheses, such as the one mentioned above: that is to say, the structure of the dialectic is different. Having said that, my own view is that the ultimate solution to the challenges both of scepticism and immaterialism (at this point in the dialectic we have effectively refuted solipsism) is to be found in the primacy of the standpoint of the agent.
Is the private language argument relevant? The gap between Kant's refutation of idealism and the private language argument is the very gap that has to be crossed in refuting solipsism. (For reasons given in the text, I am not accusing Kant of being a solipsist.)
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'Are there any questions (statements) that everyone would agree are undecidable? Or do people only ask questions/formulate propositions when they think the issue is decidable?' It's easy enough to generate undecidable statements (put a die in a box: shake it then shake again. Did the first shake produce an even number?) More realistic examples would be the thoughts of people on their death beds, love letters thrown into the fire, etc. There are circumstances that prompt us to muse about undecidable questions. (One says, 'We shall never know whether...'.)
The anti-realist does not say 'it is impossible to say' whether it is true or false that my mother's last conscious thoughts were of me. That's something both the realist and anti-realist agree on. The anti-realist says that the question does not 'have an answer in reality'. (I don't think any mileage can be got by comparing true and false with the logician's 'T' and 'F'.)
Your worries about propositions remind me of what Margaret Thatcher said about 'society'! You are quite right: We are talking of an abstraction, an abstraction that has or purports to have a certain utility, both in philosophical and logical theory and indeed (as I claimed) in ordinary speech.
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It is crucially important for understanding the metaphysics programme to distinguish between issues concerned with the nature of truth and issues concerned with the existence of this or that class of objects, or with the nature of existence as such.
There are indeed, as Dummett claims, certain questions of existence which do ultimately turn on the logical form of the relevant class of sentences/propositions, as revealed by a theory of meaning for such sentences. To take one example from Davidson, the philosopher of language might enquire whether the notion of an event is fundamental to our ontology, or whether it may be analysed in terms of other notions. However, I would disagree strongly with Dummett's estimate of the scope for the theory of meaning in resolving such issues.
The most fundamental disagreement of all, however, is that I do not accept that the realist/anti-realist debate about the nature of truth is a question about the 'form of a theory of meaning'.
Is 'true' ambiguous?
'It was the logician Alfred Tarski who formulated what he took to be a minimal requirement of any interpretation of the predicate, '...is true' ('On the Concept of Truth in formalised Languages' in Logic, Semantics, Metamathematics OUP 1956). Take any sentence, say, 'Snow is white' (Tarski's own example.) There are a number of things one can say about that sentence. For example, it contains three words, it occurs in unit 11, paragraph 220 of the moral philosophy programme, it does not contain the letter 'x', and so on. It is also true. What is so special about talk of truth is that, whatever sentence you put in quotation marks, the result of adding the predicate '...is true' is effectively to remove the quotation marks. No other predicate has this power. Or, rather what amounts to the same thing according to Tarski any predicate which has that power is the truth predicate.'
(From Pathways Reason, Values and Conduct unit 11.)
The existence of such a powerful device in a language makes possible the use of talk of truth merely as a device for emphasis. In assuring you that what I say is true, I am not adding anything of substance to what I said, but I may succeed in conveying how certain I am, or alternatively how strongly I feel about the matter in question.
Now aren't we all in pursuit of truth (as so characterised)? Don't we all want to have true beliefs rather than false ones?