A supposition is a guess or a hypothesis. Your supposition that your kids will automatically wash their hands before dinner is probably false. You'd best remind them to do it or risk dirty hands at dinner.

What's the difference between an assumption and a supposition — both nouns that are often taken as synonyms for each other? An assumption is an idea or theory that is usually made without proof. A supposition, on the other hand, has the connotation that the idea or theory is testable and provable. If you are to meet someone named Hunter, you may make the assumption that you are meeting a man. But if you know that Hunter lives in an all-female dorm, you may have the supposition that Hunter is a woman.

Definitions of supposition

n the cognitive process of supposing

the act of presupposing; a supposition made prior to having knowledge (as for the purpose of argument)
Type of:
reasoning that involves the formation of conclusions from incomplete evidence

n a message expressing an opinion based on incomplete evidence

conjecture, guess, hypothesis, speculation, surmisal, surmise
successful conjecture by unusual insight or good luck
Type of:
opinion, view
a message expressing a belief about something; the expression of a belief that is held with confidence but not substantiated by positive knowledge or proof

n a hypothesis that is taken for granted

assumption, supposal
show 6 types...
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an intuitive assumption
base, basis, cornerstone, foundation, fundament, groundwork
the fundamental assumptions from which something is begun or developed or calculated or explained
given, precondition, presumption
an assumption that is taken for granted
basic assumption, constatation, self-evident truth
an assumption that is basic to an argument
non sequitur
(logic) a conclusion that does not follow from the premises
meat and potatoes
the fundamental part
Type of:
hypothesis, possibility, theory
a tentative insight into the natural world; a concept that is not yet verified but that if true would explain certain facts or phenomena

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