Gerald J. Massey

When they abandoned the analytic-synthetic distinction, analytic philosophers substituted for it uncritical appeals to thought experiments or conceivability arguments. Although the history of philosophy is replete with thought experiments, medieval and early modern philosophers developed sophisticated theories concerning what governs what happens in thought experiments. By contrast, contemporary philosophers subscribe to the thesis of facile conception according to which casual allegations of conceivability or inconceivability are taken as good evidence of possibility or impossibility. Philosophers need to adopt standards of thought experimentation like those found in science and to ground them in a general theory of conceivability.

Despite their centrality and importance to both science and philosophy, relatively little has been written about thought experiments. This volume brings together a series of extremely interesting studies of the history, mechanics, and applications of this important intellectual resource. A distinguished list of philosophers and scientists consider the role of thought experiments in their various disciplines, and argue that an examination of thought experimentation goes to the heart of both science and philosophy

A bivalent valuation is snt iff sound (standard PC inference rules take truths only into truths) and non-trivial (not all wffs are assigned the same truth value). Such a valuation is normal iff classically correct for each connective. Carnap knew that there were non-normal snt valuations of PC, and that the gap they revealed between syntax and semantics could be "jumped" as follows. Let $VAL_{snt}$ be the set of snt valuations, and $VAL_{nrm}$ be the set of normal ones. The bottom row in the table for the wedge 'v' is not semantically determined by $VAL_{snt}$ , but if one deletes from $VAL_{snt}$ all those valuations that are not classically correct at the aforementioned row, one jumps straights to $VAL_{nrm}$ and thus to classical semantics. The conjecture we call semantic holism claims that the same thing happens for any semantic indeterminacy in any row in the table of any connective of PC, i.e., to remove it is to jump straight to classical semantics. We show (i) why semantic holism is plausible and (ii) why it is nevertheless false. And (iii) we pose a series of questions concerning the number of possible steps or jumps between the indeterminate semantics given by $VAL_{snt}$ and classical semantics given by $VAL_{nrm}$.