Thu 31 May 2012 09:10 AM
As I argue in several papers about realism, philosophers should give up their obsession with monolithic questions of realism and antirealism. So I try to emphasize other things when I teach philosophy of science. Some of these other things are causation, explanation, laws of nature, and attitude toward unification.
Positions on these issues arrange themselves into roughly three categories. Interestingly, although each has a different metaphysical picture, they are neutral on questions of realism or antirealism about unobservable entities. For example, adopting the Humean outlook of the epistemic package is compatible with affirming or denying that facts about electrons are on the list of Hume facts about the world.
The EPISTEMIC package
Exemplary adherents include Hempel, Lewis, et al.
Metaphysics: Only actual objects and events are real.
(Alternately: Only concreta exist.)
Causes are regularities.
Laws are the fundamental regularities that appear in the best system.
Probabilities are subjective credence.
Explanation is a matter of nomic expectability. The DN account (or some relative of it) using elements of the best unified system.
Unification of science is constitutive.
The MODAL package
Exemplary adherent: Armstrong
Metaphysics: Actual objects and events are real, but so are modal facts.
(Alternately: Concreta exist, but so do universals.)
Causes are relations between properties.
Laws are the fundamental necessities, relations between universals.
Probabilities could be subjective or objective (but I think that there's some pull toward subjective accounts).
Explanation is a matter of nomic expectability. The DN account (or some relative of it) using genuinely necessary laws.
Unification of science is contingent.
The ONTIC package
Exemplary adherent: Cartwright
Metaphysics: Actual objects and events are real, but so are causal capacities.
Causes are exercises of capacities, the powers of things.
Laws are a patchwork, summaries of what capacities can do in particular arrangements.
Probabilities are objective, determined by the capacities of things.
Explanation is a matter of identifying causes.
Unification of science is doomed.