For example, if we know that all men have two legs and that John is a man, it is then logical to deduce that John has two legs...... If the conclusions drawn from the original hypothesis successfully meet all these tests, the hypothesis becomes accepted as a scientific theory or law; if additional facts are in disagreement with the hypothesis, it may be modified or discarded in favor of a new hypothesis, which is then subjected to further tests.
Even an accepted theory may eventually be overthrown if enough contradictory evidence is found, as in the case of Newtonian mechanics, which was shown after more than two centuries of acceptance to be an approximation valid only for speeds much less than that of light.
Induction is contrasted with deduction, in which true premises do necessitate the conclusion......
These may occur naturally, as in the cases of radium and uranium, or may be created artificially.Roger Bacon wrote "If in other sciences we should arrive at certainty without doubt and truth without error, it behooves us to place the foundations of knowledge in mathematics." In philosophy, the concept fact is considered in epistemology and ontology.Questions of objectivity and truth are closely associated with questions of fact.All of the activities of the scientific method are characterized by a scientific attitude, which stresses rational impartiality.Measurementmeasurement,determination of the magnitude of a quantity by comparison with a standard for that quantity.First, information, or data, is gathered by careful observation of the phenomenon being studied.