Assumption, from the latin suppositĭo, refers to the action and the effect of assuming (believe or consider something as real or existing, guess by signs). Examples: «do not get angry with me, it was just a guess, "the assumption of Juan Carlos was not a mistake: we will have to work overtime", "a president cannot move to simple assumptions.
An assumption is an assumption. This takes place when the situation has not yet occurred, and although there is no evidence in this regard. A person who comes out and meets the wet can assume that, a few hours before, it was raining. However, it will not be able to verify this assumption unless, for example, she meets someone else who testified of the rain. It may be that the soil is wet because someone threw a bucket of water to clean.
Furthermore, an assumption may be a forecast or a prediction. Before a football tournament, one can assume that both teams will go to the finals because their context and the quality of their players allow to deduct such results. To test this assumption, it will take the tournament takes place because the games must be played to determine the winners.
In some circles, the assumptions are worth nothing. A judge cannot convict a suspect just because it assumes that he is guilty. It must make its verdict based on irrefutable evidence. Thus, the assumption ceases to be, and becomes a certainty.