- Appearance of contingency(metaphysics)
- The seeming possibility that something could have been otherwise—for example, pain might seem like it could have been something other than what it is.
- Contingency(as a value Leibniz wanted to preserve)
- The quality of something being possible but not necessary—it could be different than it is, or might not happen at all.
- Identity (philosophical)(as used in metaphysics and logic)
- When two things are actually the same thing, not just similar—like how Clark Kent and Superman are identical (the same person with two names).
- a posteriori(Used to classify the epistemic status of necessary statements post-Kripke)
- Knowable, but not independently of empirical experience
- a posteriori identity(Philosophy of science and metaethics; contrasted with a priori identities)
- An identity claim that is established through empirical investigation rather than conceptual or logical analysis alone.
- phenomenal character(Used to distinguish the mere presence of experience from the specific qualitative nature of individual experiences)
- The qualitative, subjective 'what it is like' aspect of mental states; the property of having qualia
- rigid designation(Illustrated by the indexical 'I', which rigidly designates the speaker of the context even when evaluated at counterfactual circumstances)
- An expression rigidly designates when, uttered in a fixed context, it refers to the same entity across all circumstances of evaluation