What does supposition mean?
A supposition is something taken to be true, usually so that an argument, decision, or investigation can proceed. The word is especially associated with formal reasoning: a supposition may serve as a starting point that is later supported, challenged, or disproved. For example, a theory might begin with the supposition that a particular pattern in the data has a non-random explanation. In ordinary use, “supposition” is more formal and deliberate than “guess” and more explicitly conditional than “idea.” It can also denote the act of assuming something, although this sense is less common. The word is useful when describing the provisional foundations of an argument or plan, while also making clear that the proposed starting point has not necessarily been established as a fact.
nounAn idea or statement accepted as true for the sake of argument or investigation, especially as a starting point. It can also refer to the act of assuming something to be true.
- An idea or proposition accepted as true as the basis for an argument, decision, or investigation.
- The act of assuming something to be true.
- A proposition introduced in a logical or mathematical argument as an assumption.
"The entire plan rested on the supposition that demand would remain steady."
"The investigation began with the supposition that the missing document had been removed."
"Under the supposition that costs would not rise, the committee approved the design."
Supposition can be countable when referring to individual assumptions and uncountable when referring to the act of assuming something.
"The researchers tested several competing suppositions about the origin of the signal."
A supposition is the grammatical engine of “What if?”
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of supposition
Supposition comes through Latin suppositio, a noun meaning an assumption or supposition. That Latin word is derived from supponere, formed from sub- meaning “under” and ponere meaning “to place” or “to put,” and is also the source of the English verb suppose. English developed several related forms, including suppositional, while supposition became especially established in formal logical and philosophical writing.
Related word forms
How supposition is actually used
Supposition is formal and especially common in academic, legal, logical, and mathematical writing. It is less typical in casual conversation than assumption or guess.