Thursday, February 23, 2006

Quasi-Realism No Fictionalism (But Not Quite For Blackburn's Reasons)

I've just been leading the MRG on the Lewis/Blackburn exchange in this collection concerning whether quasi-realism is fictionalism (Blackburn's half of which is online here).

It seems to me that Lewis's claim that quasi-realism is a version of fictionalism is mistaken, but not for a reason that comes through in Blackburn's response.

Lewis's argument, in essentials, is that the quasi-realist wants to say everything the realist does, so must either be a realist or be making believe that realism is true. But he is not a realist, therefore he is making believe that realism is true, i.e. he's a fictionalist.

I think we can show what's wrong with that argument in a few lines. The sense in which the quasi-realist 'says everything the realist does' is not the one which enforces either being or pretending to be a realist. This would be enforced if the quasi-realist was making the same assertions as the realist, but he isn't (indeed, the paradigm quasi-realist isn't making assertions at all). The quasi-realist says things which sound like what the realist says, but they are to be interpreted differently - in the moral case, as expressions of attitudes, rather than as committing to moral properties. Expressing an attitude requires neither belief in moral properties (realism) or pretense that moral properties exist (making believe that realism is true).

So here's why quasi-realism is not fictionalism:
The fictionalist differs from the realist in adopting the realist account of the meaning of the target sentences but dissenting from those sentences (same content, different attitude) whereas the quasi-realist differs from the realist in adopting a different account of the meaning while continuing to accept those sentences (different content, same - or at least similar - attitude).

Wednesday, February 15, 2006

Entitlement and Rationality

My paper on Crispin Wright's notion of Entitlement is now also up - though NB still in draft form - on my home page. Comments welcome on this too!

Tuesday, February 14, 2006

Knowability Again

I've just posted the final draft of my knowability paper on my home page. Comments are still welcome!

Wednesday, February 08, 2006

New Arche Blog

Arche now has a blog on which all Arche members can create posts. The aim is to encourage philosophical interaction between Archeans and friends around the world. We also welcome participation from other philosophers - comments are publicly open.

Tuesday, February 07, 2006

Cook on Unknowability

Roy Cook has just argued that there are some unknowable propositions provided it is possible for the following situation to obtain. Ava, Brigitte and Dorothy are all inhabitants of Smullyan’s (1978) island occupied solely by knights and knaves. Knights are people who always speak truly, knaves are people who always speak falsely. Simultaneously, they utter the following:
Ava: What Brigitte is now saying cannot be known to be true
Brigitte: What Dorothy is now saying cannot be known to be true
Dorothy: What Ava is now saying cannot be known to be true

Cook shows that if this happens then at least two of Ava, Brigitte and Dorothy must be knights (see his p. 12), and goes on to show as a consequence of this that at least one of them – we do not know which one – has uttered a true but unknowable proposition. He assumes classical logic and certain facts about the behaviour of the knowability operator in order to get this result, all of which we can grant here for the sake of argument.

Cook stresses that his argument relies on the thought that the scenario he describes is free from ‘any paradox, failure of reference, or other pathology’ (p. 14). It seems to me, however, that the anti-realist who accepts the principle p --> Kp will think Cook’s scenario is paradoxical, because it presents a version of the paradox raised by what Cook would call the semantic open triple (sorry, no corner quotes):
p: ¬Tq
q: ¬Tr
r: ¬Tp
(where T is the truth predicate). No assignment of (classical) truth values to these three propositions is consistent.

Anti-realists for Cook’s purposes are those who accept that if p then p is knowable, which Cook represents as p --> Kp, the contrapositive of which is ¬Kp --> ¬p. By this and the contrapositive of disquotation for the truth predicate, ¬p --> ¬Tp, these anti-realists will also accept that ¬Kp implies ¬Tp. Hence the three characters in Cook’s story are uttering claims which are either stronger than or identical in strength to the paradox-creating claims of the semantic open triple. In fact, anti-realists will presumably think the claims are identical in strength; for they are happy to accept ¬Kp --> ¬Tp, and ¬Tp --> ¬Kp is trivial.

One might respond that this is to beg the question; the only reason that is being offered for thinking that Cook’s situation is paradoxical is adherence to p --> Kp, which, of course, one does not accept unless one is an anti-realist.

But we need to be clear about where the burden of proof lies. Cook is (tentatively) offering an argument that should be capable of persuading anti-realists that there could be an unknown truth. To do this, as he acknowledges, the situation he describes should not be paradoxical. But the anti-realist will think it generates a Liar-like paradox, namely the semantic open triple. Therefore Cook’s argument will not be persuasive to an anti-realist.