[lit-ideas] Re: Mackie on Popper and Popper in reply

From: Donal McEvoy <donalmcevoyuk@xxxxxxxxxxx>
To: lit-ideas@xxxxxxxxxxxxx
Date: Fri, 1 Apr 2011 18:04:00 +0100 (BST)
Somewhere [_Mind_?] Mackie reviewed Popper's Schilpp volumes and, if memory 
serves, suggested that Popper's conception of World 3 was logically flawed. 
Popper conceives W3 as 'growing' with the addition of new theories etc., yet 
also allows that W3 contains true and false theories and contradictory 
theories. Mackie retorts that as anything and everything follows from two 
contradictory propositions, then from the point contradictory propositions are 
admitted to W3 it must contain everything as a matter of logic, and as such W3 
cannot 'grow'.

Without mentioning Mackie, I put to this point to Popper when a college friend 
and I visited him at his home in Kenley in about 1988. We were seated outside 
on a patio. Popper said nothing but dashed inside. We waited. He returned with 
a book and found a footnote on a page. The book turned out to be his 'LdF' and 
in the footnote Popper said he had introduced into British philosophy an 
important distinction that even Russell had overlooked (I think it may have 
been the distinction between logical and material implication, in some form).

Popper then gave his reply by using one of the coffee cups on the table as 
representing W3 qua container. We can then put a proposition on a piece of a 
paper into the container and then another piece of paper containing the 
negation of that proposition. This admits a contradiction into the container, 
but it does not make the container into a contradiction and it does not fill up 
the container with other pieces of paper. All it means is that whatever further 
proposition on a piece of paper we might put in the container, that proposition 
is not ruled out from being put in the container on the basis that it stands in 
some contradictory position to something already in the container.

My understanding of his reply was that while everything follows from two 
contradictory propositions, all this means is that given any two contradictory 
propositions any other proposition is logically permissible (because by 
admitting contradictions everything becomes logically permissible): it does not 
follow that any further proposition follows in any more concrete sense. By 
admitting contradictory propositions to W3, Popper is therefore being 
permissive as to the conditions of admissibility to W3 but those permissive 
conditions do not themselves constitute or entail the existence of any specific 
theory. Therefore, by admitting contradictions Popper is not committed to the 
view that it is not then possible for the content of W3 to be enlarged (or to 
'grow') through the addition of further specific theories.

If Popper was correct here (perhaps suggesting btw that certain critics might 
avoid misplaced criticism if they paid more addition to footnotes in some of 
his very old work), then perhaps Mackie is capable of some headlong logical 
blunder such as Dworkin seemingly implies.

Donal
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[lit-ideas] Re: Mackie on Popper and Popper in reply

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