   __notoc__ empirical evidence (also empirical data, sense experience, empirical knowledge, or the a posteriori) is a source of knowledge acquired by means of observation or experimentation. the term comes from the greek word for experience, ÎÎ¼ÏÎµÎ¹ÏÎ¯Î± (empeirÃ­a). empirical evidence is information that justifies a belief in the truth or falsity of a claim. in the empiricist view, one can claim to have knowledge only when one has a true belief based on empirical evidence. this stands in contrast to the rationalist view under which reason or reflection alone is considered to be evidence for the truth or falsity of some propositions. the senses are the primary source of empirical evidence. although other sources of evidence, such as memory, and the testimony of others ultimately trace back to some sensory experience, they are considered to be secondary, or indirect. in another sense, empirical evidence may be synonymous with the outcome of an experiment. in this sense, an empirical result is a unified confirmation. in this context, the term semi-empirical is used for qualifying theoretical methods which use in part basic axioms or postulated scientific laws and experimental results. such methods are opposed to theoretical ab initio methods which are purely deductive and based on first principles. in science, empirical evidence is required for a hypothesis to gain acceptance in the scientific community. normally, this validation is achieved by the scientific method of hypothesis commitment, experimental design, peer review, adversarial review, reproduction of results, conference presentation and journal publication. this requires rigorous communication of hypothesis (usually expressed in mathematics), experimental constraints and controls (expressed necessarily in terms of standard experimental apparatus), and a common understanding of measurement. statements and arguments depending on empirical evidence are often referred to as a posteriori ("from the later") as distinguished from a priori ("from the earlier"). (see a priori and a posteriori). a priori knowledge or justification is independent of experience (for example "all bachelors are unmarried"); whereas a posteriori knowledge or justification is dependent on experience or empirical evidence (for example "some bachelors are very happy"). the notion of the distinction between '
Empiricism Epistemology_of_science Evidence Experiments Justification Observation Sampling_(statistics) Scientific_method Sources_of_knowledge Statistical_terminology