The Nature of Necessity

Alvin Plantinga

1. broadly logical necessity is not equivalent to--
causal necessity or natural necessity
unrevisability or ungiveupability
self-evident
a priori

2. modality de dicto & modality de re
modality de re can be explained in terms of modality de dicto
(so if one accepts modal de dicto, one has no good reason to reject de re modality)

on the other hand, de dicto modality can be thought of as a special case of de re modality.

a scheme of translating de re to de dicto modality--
A is necessarily P.
A is P and that A is not P is necessarily false.

e.g. Socrates is necessarily a person.
Socrates is a person and that Socrates is not a person is necessarily false.