The purpose of this article is to explain the differences between the two types of modality: deontic and epistemic.

Deontic modality refers to possible worlds where an agent performs an action. For example, if I say “I can speak French”, then I am talking about a possible world where I speak French. Similarly, if I say “I could have been a doctor”, then I am talking about a different possible world where I am a doctor but also that I did not become one.

In both cases, the agent has not actually performed the action in question (speaking French or becoming a doctor) but it is still possible for him to do so. Epistemic modality in contrast refers to beliefs or knowledge claims rather than actions. For example, when someone says “I know that she is dancing” they are referring to their belief that she is dancing even though we might be mistaken about this fact (she may not be dancing after all).

The reason why these two meanings are often conflated is that there are cases where they overlap such as when we say “She could have danced better” or “She will dance better next time” These statements.

Last modified: September 6, 2022