 A hypothesis plural hypothesis is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can't test it. Scientists generally base scientific hypotheses on previous observations that cannot satisfactorily be explained with the available scientific theories. Even though the words hypothesis and theory are often used synonymously, a scientific hypothesis is not the same as a scientific theory. The working hypothesis is a provisionally accepted hypothesis proposed for further research, in a process beginning with an educated guess or thought. A different meaning of the term hypothesis is used in formal logic, to denote the antecedent of a proposition, thus in the proposition of p, then q p denotes the hypothesis or antecedent q can be called a consequent. p is the assumption in a possibly counterfactual what-of question. The adjective hypothetical, meaning having the nature of a hypothesis or being assumed to exist as an immediate consequence of a hypothesis can refer to any of these meanings of the term hypothesis.