Evidence in its broadest sense includes anything that is used to determine or demonstrate the truth of an assertion.

Philosophically, evidence can include propositions which are presumed to be true used in support of other propositions that are presumed to be falsifiable. The term has specialized meanings when used with respect to specific fields, such as policy, scientific method, criminal procedures, and legal discourse.

The most immediate form of evidence available to an individual is the observations of that person's own senses. For example an observer wishing for evidence that the sky is blue need only look at the sky. However this same example illustrates some of the difficulties of evidence as well:

• someone who was blue-yellow color blind, but did not know it, would have a very different perception of what color the sky was than someone who was not. Even simple sensory perceptions (qualia) ultimately are subjective; guaranteeing that the same information can be considered somehow true in an objective sense is the main challenge of establishing standards of evidence.
• there is also the question of what is meant by 'blue', and how we measure it. (If determined by a particular wave-length of colour - then how do we actually measure this?)
• there is also the question of how evidence 'translates' e.g. is 'blau' in German universally translated as 'blue' in English: Germans may have different words for different parts of the spectrum; thus 'evidence' is a social construction.

Burden of Proof

Contemporary concepts about evidence revolve largely around the Burden of Proof Beyond a Reasonable Doubt.

In Science: the Burden of Proof is on the presenter of a Thesis paper, in which the presenter of a specific argument is to present a paper of findings. This paper is then placed before a panel of judges where the presenter must defend the Thesis against all challenges.

In the court of law: the Burden of Proof is placed on the Prosecution. Prosecution presents a suit of charges with which to accuse another party. Defense, representing the accused, must make a plea about the truth of the accusation. Before trial is adjourned, the Jury must render a verdict of guilty or not guilty based on each individual charge.

Evidence in science

main: Scientific evidence In scientific research evidence is accumulated through observations of phenomena that occur in the natural world, or which are created as experiments in a laboratory. Scientific evidence usually goes towards supporting or rejecting a hypothesis. When evidence is contradictory to predicted expectations, the evidence and the ways of making it are often closely scrutinized (see experimenter's regress) and only at the end of this process the hypothesis is rejected: this can be referred to as 'refutation of the hypothesis'. The rules for evidence used by science are collected systematically in an attempt to avoid the bias inherent to anecdotal evidence: nonetheless even anecdotal evidence is enough to reject a theory incompatible with that evidence, if there are sufficient repeated examples.