Thursday, June 04, 2009

The Theory of Descriptions according to Wikipedia

So Peter Smith couldn't help correcting Wikipedia's entry about the Theory of Descriptions here. I am not sure if his point is entirely fair. (Certainly there are far worse things on Wikipedia philosophy and logic he could have tried to fix, e.g. this abomination).

It depends on what problem the Theory of Descriptions is intended to fix. The medieval Latin philosophers faced a similar problem and they arrived at a substantially similar solution to Russell, but they didn't have a distinction between 'a' and 'the' (which is the focal point of Peter's correction). So logicians such as Ockham were no wiser than Wikipedians?

The problem that Ockham (and the early Scotus, Robert Kilwardby and many others) were trying to fix was that 'Chimera is white' and 'Chimera is not white' are both false. But Aristotle says that de quolibet dicitur affirmatio vel negatio vera - either the affirmation of any sentence is true, or its negation is. Ockham argues that the second sentence is not really a negation of the first, for it can be unpacked as 'Chimera is something and it is not white'. The real negation, by contrast, is 'Chimera is not something or it is not white'. (Ockham like the other medievals was not worried here about uniqueness claims).
If the problem to be solved is not a 'non denoting description' but rather the one outlined above, namely that '[the] present King of France is bald' '[the] present King of France is not bald' are both false, then the original Wikipedia entry is not off the rails entirely.

Or perhaps he is objecting to something else, namely that unpacking 'chimera is white' into 'chimera is something-white' leads to an infinite regress. The medievals discussed this problem too. They saw that if 'Caesar est homo' = 'Caesar est ens homo', i.e. 'est' always unpacks into 'est ens', then this leads to an infinite regress, 'Caesar est ens homo' = 'Caesar est ens ens homo' and so on. Nicholas of Paris, Robert Bacon (not to be confused with Roger) discussed this in the early 13th century. But that is something else.

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