The act of presupposing; an antecedent implication; presumption.
PH Initial assumptions upon which all thought is based. Presuppositions are often difficult to observe or prove because they stand prior to proof and become the standard by which other ideas or arguments are tested. A presupposition may be fundamental to all inquiry ("I exist") or simply agreed upon by the parties to a discussion without prior proof ("For the purposes of this debate, let us assume . . . . "). All arguments are based upon presuppositions, such as the uniformity of nature (in the case of scientific proofs) or the universality of the laws of logic (a contradiction today will remain a contradiction tomorrow).
1 - Something that has to be taken for granted for a behavior or statement to make sense. 2 - The linguistic equivalents to assumptions. Of NLP, Convenient beliefs or assumptions you make when you are doing therapy with someone.