Epistemic modality is a linguistic modality that expresses how certain a speaker is about the proposition being uttered. It is expressed by the use of modal verbs such as "might" or "must" and adverbials such as "probably" or "possibly." Evidentiality is a kind of epistemic modality that denotes the source of the information being given. The second type of epistemic modality is judgment modality which connotes the speaker's degree of confidence or strength of inference in what they are saying.
The linguistic expression of hypothetical situations is based on interpretation or evaluation and this is expressed using modal verbs, adverbials, intonation patterns, affixes or particles. An epistemic modality presents the possibility or the necessity of an underlying proposition which is known as the prejacent. This is expressed relative to some kind of evidence or knowledge. Modality allows the evaluation of a proposition, or modal force, in relation to a set of other propositions, the modal base.
In linguistics, modality usually follows this template: "According to (certain wishes, rules, conditions, beliefs), it is (possible, probable, necessary) that (the proposal being stated) is the case." "According to.." is the restrictor phrase which quantifies the word being determined in the statement. There are different types of modality of which epistemic modality is only one. The others are deontic, bouletic, circumstantial and teleological. The same modal verb can express each of these modalities and the difference will depend on contextual factors.
Epistemology is the study of knowledge and justified belief. It is concerned with the source of the knowledge being expressed and how justified the claims being made. This creation and dissemination of knowledge is a part of everyday conversation and socialization and the trust one person has in the utterances of another is based on a tripartite of knowledge which is that knowledge requires belief which requires justification.
Epistemic probability is a school of thought which comes under the umbrella of Bayesianism, a philosophy that believes the mathematical theory of probability can be applied to the degree of plausibility of statements. As probability can be a vague subjective concept, the aim of epistemic probability was to provide a mathematical model and make the concept more objective. When one person says "might," it does not always comply with the probability assumed by another when they use the same word. Thus, believability is dependent on the reliability inspired by the speaker. An epistemic probability has to do with the possession of knowledge or information which allows the making of statements.