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Tuesday, May 21, 2013

Plantinga on Antirealism

So I decided to read Alvin Plantinga's How to be an Anti-Realist which I thought might be interesting. Unfortunately I was disappointed.

I won't present a thorough discussion of the paper but I will draw upon one bit of reasoning I found a bit goofy.

On pages 64-66 (19-21 of the pdf), Plantinga presents an argument against anti-realism. The argument runs a page and a half and goes something like this:
(3) p is true if and only if (if there were an Ideally Rational Scientific Community (IRS), it would accept p). 

[insert a bunch of modal logic nonsense1]

(14) Necessarily, there is an IRS.
I immediately noticed a problem with his premise (3) which will become obvious in a moment as I will offer a much simpler argument than Plantinga offered that won't require the use of any modal logic.

First we'll take (3) as given as Plantinga begins. Here's the proof (by contradiction).

Assume that there is no IRS. 

Since there is no IRS, then the antecedent in the conditional - (if there were an Ideally Rational Scientific Community (IRS), it would accept p) - is false which means the conditional is true. Therefore p is true for any p. Hence, we can conclude that both p and ¬p are true which is a contradiction.

Therefore there is an IRS.

Granted, I haven't technically proven (14) since I lack the necessary operator but it's still in the spirit of his argument (without all of the modal fuss). 

I'm not sure why any anti-realist that Plantinga is discussing would need to accept his (3). My guess is that many anti-realists of the flavor Plantinga is discussing would consider, in the event that there is no IRS, that p has no truth value whatsoever.  So (3) would have to be considered a straw man.

What are alternatives? I suppose we can change the conditional statement in (3) to an "and":
p is true iff (there is an IRS and that IRS accepts p).
With regard to my own sympathies with anti-realism (and I have realist sympathies as well), I tend to side more with a form of contextualism2, so I wouldn't postulate an IRS at all.

1 I don't actually object to modal logic per se but I'm not a huge fan of how these systems typically get axiomatized and I've never much cared for the "worlds" heuristics that are used. But that discussion would have to be reserved for another time.
2 Contextualism is, more or less, a less pejorative term for "relativism".

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