Wednesday, September 01, 2004

Logic and Possibility

The Maverick Philosopher responds to my charge of question-begging:
Rethinking this, my argument strikes me as logically impeccable. Am I assuming what I need to prove? Not that I can see. What I am arguing, very simply, is that LNC cannot be an empirical generalization since if it were, it would be logically contingent, i.e., logically possible false. But this is absurd since LNC is the criterion of logical possibility. LNC defines what it is to be a logically possible world. Hence a logically possible world in which LNC fails to be true is a world in which a contradiction is true. Hence, by RAA, (1) is false.

To make things clearer, I have emphasised in bold the exact stage which strikes me as question-begging.

I could be mistaken here, but as I understand it, to question the necessity of the laws of logic is to question their metaphysical necessity. Surely no-one would doubt that the laws of logic are logically necessary. That's as absurd as doubting that the laws of nature are 'naturally necessary' (by the definition given in my previous post). It's just an empty tautology - as Bill himself noted, "LNC is the criterion of logical possibility". So long as we remain within the framework of classical logic, it is trivially true that the laws of logic could not possibly be false. They are true by definition - by mere stipulation.

And that is why I consider it question-begging to defend the necessity of logic by merely pointing out that it is "logically necessary". For that (I take it) is not in question. Instead, we are asking whether we must be bound by the limits of classical logic. We are asking whether this system itself is necessary (in the broadest sense, which I take to be metaphysical necessity). One cannot answer this, as the Maverick Philosopher seeks to, by remaining within the system and saying that from this position, the system is necessary. That is question-begging. You could make that move of any system whatsoever. From within the framework of natural laws, the laws of physics are necessary and not merely contingent. But of course, that doesn't really say anything much at all.

So, to repeat the central point of my previous post, modal notions must be assessed against some background framework of limitations. Something might be necessary within one framework, but merely contingent within another. Perhaps this is the case with classical logic? (I take it that the Maverick Philosopher considers the metaphysically possible to be a subset of the logically possible, whereas I would consider the relation to be reversed. Indeed, as discussed in the previous post, I have trouble seeing how we could justifiably rule out anything as being impossible in the broadest sense - which is how I understand metaphysical possibility.)

Having said all that, I don't actually think the laws of logic are mere "empirical generalisations" either. I think it more likely that our brains are hardwired to think in that way, in much the same way that we are hardwired to perceive the world in terms of absolute space and absolute time. But just as our intuitions about the latter are mistaken, and just as Euclidean geometry turned out to be but one possible system among many, so do I think that classical logic might suffer from similar imperfections.

So I'm actually defending a position slightly different from that which the Maverick Philosopher was attacking. Nevertheless, I still think his 'reductio' begged the question against the empiricist. For I take it that the empiricist claims not that the laws of logic are logically contingent, but rather, that they are metaphysically contingent. Logic, he suggests, is generalised from our experience of reality, but that reality could have been different, and so our logical systems could have been different. Of course, that new logic would be 'impossible' according to the constraints of classical logic ("logical possibility"). But that is to be expected, given that it is precisely those constraints that are in question here. To appeal to those constraints (i.e. logical possibility) in their own defense is indeed to beg the question.

Update: more here.


  1. Hey there,

    I'm also an undergrad student in philosophy as well (philosophy/psychology actually) here in Canada. I looked over your site and its awesome! Keep up the good work. Very interesting thoughts and ramblings. hehe.

    Take care,

    Posted by Annie

  2. Richard,

    Would you happen to know why the notion of correspondence is a problem for epistemology? What are your thoughts concerning this?


    Posted by Annie


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