METAPHYSICS – AN OVERVIEW : What Is Metaphysics?

A Definition of Metaphysics:  Metaphysics is the philosophical investigation of the ultimate nature of reality.

Some Basic Types of Questions in Metaphysics:  (1) Questions concerning reality as a whole;  (2) Questions concerning things that must be true of absolutely everything that exists;  (3) Questions concerning possibilities for existence;  (4) Questions concerning fundamental aspects of contingent things;  (5) Questions concerning the nature of human beings.

The Problem of Method in Metaphysics:  Science, especially physics, is also concerned with arriving at knowledge of the ultimate nature of reality.  How do the methods used in metaphysics relate to, and differ from, the methods used in science?  Is metaphysics a legitimate discipline, rather than pure speculation, or armchair science?

Methods Used in Metaphysics, and Some Examples:  (1) The appeal to what one can imagine – where imagining some state of affairs involves forming a vivid image of that state of affairs. (2) The appeal to what one cannot imagine. (3) The appeal to what one can coherently conceive. (4) The appeal to what one cannot coherently conceive. (5) The appeal to intuitions about what is logically possible, or logically impossible, to support claims about what really is logically possible, or logically impossible.  (Comment:  Appeals of these five sorts occur, for example, in connection with the evaluation of proposed analyses of concepts, and in connection with attempts to formulate truth conditions.)  (6) Conceptual analysis  (7) The proof of propositions using logic alone.  (Bertrand Russell and (a) the non-existence of set of all sets that do no belong to themselves, and (b) the non-existence of a set of all sets)  (8) The proof of propositions using logic plus conceptual analysis.  (Analytic truths as derivable from logical truths in the narrow sense by the substitution of synonymous expressions.)  (Examples:  A cause cannot succeed its effect.  All properties are completely determinate.) 
(9) The use of inference to the best causal explanation.  (Examples:  God; other minds)  (10) The use of inference to the best non-causal explanation.  (Examples:  Laws of nature; causal relations) (11) The use of a system of logical probability to show that certain things are likely to be the case, or that certain things are unlikely to be the case.  (12) The use of inference to the best account of the truth conditions of some statement.  (The idea of a robust correspondence theory of truth)  (Example:  David Lewis's account of the truth conditions of statements about possibilities.)  (13) The appeal to direct acquaintance.  (Example:  The existence of emergent, sensuous properties)

The Status of Metaphysical Truths, and Questions of Method:  Are some metaphysical propositions merely contingently true?  If so what methods can be used to establish such contingent truths?  Are some metaphysical propositions necessarily true?  What methods are appropriate in such cases?

Truthmakers and Metaphysical Propositions:  Do all true statements require truthmaking states of affairs that are external to the statements?  What about logically true, or analytically true statements?  (Compare Lewis's postulation of possible worlds to supply truthmakers for modal statements.)