From Hardegree to Chellas for Joyce + Restall

From: Bruno Marchal <marchal.domain.name.hidden>
Date: Wed, 25 Sep 2002 12:02:20 +0200

Hi Wei,

I am still thinking on books, prerequisites, etc.



I think the following paper:



Hardegree, G. M. (1976). The Conditional in Quantum Logic. In Suppes, P.,
editor, Logic and Probability in Quantum Mechanics, volume 78 of Synthese
Library, pages 55-72. D. Reidel Publishing Company, Dordrecht-Holland.


could be at the intersection of your interest in decision theory,
and the comp derivation of physics. At least both could make some use of
the Stalnaker - Lewis "other worlds" type of semantics. Unfortunately
the Hardegree-Stalnaker-Lewis counterfactuals appears in my work through
the use of the movie-graph argument (MGA), (cf Maudlin's argument we talk
some time ago)---as opposed to the UDA more easily
understandable by those open to the everything-list's "more is simpler"
principle.


Just to tell you that the Joyce book you refer to us is indeed
interesting and could motivate for mathematical tools common in decision
theory, philosophical logic, and theories related to the machine interview
I am engaged in.

Note that the "Stalnaker Hardegree Lewis semantics" belongs to the family
of modal semantics described in the last chapters of Chellas' book
(Minimal Model, Conditional). You could perhaps even bypass Kripke
semantics, and read those last chapters in priority.

So, if you study Chellas last chapter, that will help you both to deepen
your appreciation of Joyce, and will help for the understanding of my thesis.

Take a look on http://www.phil.mq.edu.au/isl/, the web page on
Greg Restall book on "substructural logics".
I have not yet read that book, but that book makes an unified treatment
of many "weak" logics (in particular those you get by weakening
the structural rules). It gives an intro to the "Goldblatt frames" for non
distributive logic(like quantum logic), to the linear logics and the coherence
conditions. Giving the importance of resource in causalist decision theory
I would bet on the relevance of such logics. He makes also a little
intro to the use of category in those logics, but not enough (imo!).
Another defect is that he changes the notation in linear logic, which is
confusing.

Bruno

PS I have found a way to explain with knot theory what "logic" is,
as a branch of math, by comparing propositions with knots, proofs with
continuous deformation, and semantics with knot's invariants. As I said
before one of the difficulty for writing a paper is the misunderstanding
between logicians and physicist ...
Received on Wed Sep 25 2002 - 03:06:55 PDT

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