Evidence.html |
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Evidence in its broadest sense includes everything 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.
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Burden of proof
The burden of proof is the burden of providing sufficient evidence to shift a conclusion from an oppositional opinion. He who does not carry the burden of proof carries the benefit of assumption. He who bears the burden of proof must present sufficient evidence to move the conclusion to his own position. The burden of proof must be fulfilled both by establishing positive evidence and negating opositional evidence.
There are two primary burden-of-proof considerations:
1) The question of on whom the burden rests.
2) The question of the degree of certitude the proof must support. This depends on both the quantity and quality of evidence and the nature of the point under contention. Some common degrees of certitude include the most probable event, reasonable doubt, and beyond the shadow of a doubt.
Conclusions (from evidence) may be subject to criticism from a perceived failure to fulfill the burden of proof.
Evidence in science
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.
One must always remember that the burden of proof is on the person making this positive claim. Within science, this translates to the burden resting on presenters of a papers, in which the presenter argues for their specific findings. This paper is placed before a panel of judges where the presenter must defend the thesis against all challenges.
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.
Evidence in law
Many might say evidence forms the very foundation of any legal system, without which law would be subject to the whims of those with power. Evidence is currency of a legal system fair to all.
In law, the production and presentation of evidence depends first on establishing on whom the burden of proof lies. There are two primary burden-of-proof considerations in law. The first is on whom the burden rests. In many, especially Western, courts, the burden of proof is placed on the prosecution. The second consideration is the degree of certitude proof must reach, depending on both the quantity and quality of evidence. And these degrees are different for criminal and civil cases, the former requiring evidence beyond a reasonable doubt, the later considering only what most likely happened. The decision maker, often a jury, but sometimes a judge, is required to decide whether the burden of proof has been fulfilled.
After deciding who will carry the burden of proof, evidence is first gathered and then presented before the court:
Gathering evidence
In criminal investigation, rather than attempting to prove an abstract or hypothetical point, the evidence gatherers attempt to determine who is responsible for a criminal act. The focus of criminal evidence is to connect physical evidence and reports of witnesses to a specific person. While this is supposedly a non-biased act, detectives sometimes have agendas of their own.
Evidence before the court
Presenting evidence before the court differs from the gathering of evidence in important ways. Gathering evidence may take many forms; presenting evidence that tend to prove or disprove the point at issue is strictly governed by rules, failure to follow leading to any number of consequences. In law, certain policies allow (or require) evidence to be excluded from consideration based either on indicia relating to reliability, or broader social concerns. Testimony (which tells) and exhibits (which show) are the two main categories of evidence presented at a trial or hearing. In federal court, evidence is admitted or excluded under the Federal Rules of Evidence. [1]
Evidence in software
Evidence is a way of uniquely identifying a version of software.
Evidence in statistics
This is the key of statistical inference, for which see e.g. the work of Allan Birnbaum and others.
Types of evidence
External sources
- ASTM E141 Standard Practice for Acceptance of Evidence Based on the Results of Probability Sampling