Problems of method : how to think about the a posteriori part of the inquiry ? Remarks on the relationship between metaphysics and science

Secondly, we must be wary of the a priorist temptation: remember that logic and semantics are linked to our empirical "reasons" and therefore to scientific discoveries. This requires us to take science into account, but not to be taken in by it. There are remedies againsta priorism: the practice of modal logic; the use and questioning of our intuitions; thought experiments, taking into account the contributions of the sciences of cognition and experimental psychology (links between norms and nature). So we mustn't give in too quickly to the "anti-reductionist consensus", but rather look for new reductionist models. Some remedies against scientism: stop thinking that metaphysics begins where science ends; accept methods other than those prevalent in the sciences: conceptual analysis, abduction, prima facie justifications; admit that metaphysical statements can make sense, even if they are not susceptible to empirical confirmation or invalidation, that there can be, if not non-scientific, at least a-scientific reasons to believe (Putnam), which does not imply that these reasons must necessarilyprevail over the reasons given to us by science. A few rules, then, of good conduct and a double wager: in the event of conflict between a scientific theory and a metaphysical theory, operate a double work of undermining and counter-argument; remember that the "unity" of science remains an "ideal"; satisfy the double constraints of categorization and empirical adequacy. Last but not least, we rely on scientific realism to interpret theories, and on a metaphysical commitment to the nature of things and their properties. Do the sciences come into conflict with dispositional essentialism? This is the question that the following lectures (5 to 9) set out to address, by subjecting it to the test of empirical science.