evidence

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Evidence for a
proposition In logic and linguistics, a proposition is the meaning of a declarative sentence (linguistics), sentence. In philosophy, "Meaning (philosophy), meaning" is understood to be a non-linguistic entity which is shared by all sentences with the same mea ...
is what supports this proposition. It is usually understood as an indication that the supported proposition is true. What role evidence plays and how it is conceived varies from field to field. In
epistemology Epistemology (; ) is the concerned with . Epistemologists study the nature, origin, and scope of knowledge, epistemic , the of , and various related issues. Epistemology is considered a major subfield of philosophy, along with other major ...

, evidence is what justifies
beliefs A belief is an Attitude (psychology), attitude that something is the case, or that some proposition about the world is truth, true. In epistemology, philosophers use the term "belief" to refer to attitudes about the world which can be either tru ...
or what makes it
rational Rationality is the quality or state of being rational – that is, being based on or agreeable to reason Reason is the capacity of consciously making sense of things, applying logic Logic (from Ancient Greek, Greek: grc, wikt:λογι ...
to hold a certain doxastic attitude. For example, a perceptual experience of a tree may act as evidence that justifies the belief that there is a tree. In this role, evidence is usually understood as a private mental state. Important topics in this field include the questions of what the nature of these mental states is, for example, whether they have to be propositional, and whether misleading mental states can still qualify as evidence. Other fields, including the sciences and the legal system, tend to emphasize more the public nature of evidence. In philosophy of science, evidence is understood as that which '''' or ''disconfirms'' scientific hypotheses. Measurements of Mercury's "anomalous" orbit, for example, are seen as evidence that confirms Einstein's theory of general relativity. In order to play the role of neutral arbiter between competing theories, it is important that scientific evidence is ''public'' and ''uncontroversial'', like observable physical objects or events, so that the proponents of the different theories can agree on what the evidence is. This is ensured by following the
scientific method The scientific method is an empirical Empirical evidence for a proposition is evidence, i.e. what supports or counters this proposition, that is constituted by or accessible to sense experience or experimental procedure. Empirical evidence ...

and tends to lead to an emerging scientific consensus through the gradual accumulation of evidence. Two issues for the scientific conception of evidence are the problem of underdetermination, i.e. that the available evidence may support competing theories equally well, and theory-ladenness, i.e. that what some scientists consider the evidence to be may already involve various theoretical assumptions not shared by other scientists. It is often held that there are two kinds of evidence: ''intellectual evidence'' or what is self-evident and ''
empirical evidence Empirical evidence for a proposition In logic and linguistics, a proposition is the meaning of a declarative sentence (linguistics), sentence. In philosophy, "Meaning (philosophy), meaning" is understood to be a non-linguistic entity which is s ...
'' or evidence accessible through the senses. In order for something to act as evidence for a hypothesis, it has to stand in the right relation to it, referred to as the "evidential relation". There are competing theories about what this relation has to be like. Probabilistic approaches hold that something counts as evidence if it increases the probability of the supported hypothesis. According to hypothetico-deductivism, evidence consists in
observation Observation is the active acquisition of information Information can be thought of as the resolution of uncertainty; it answers the question of "What an entity is" and thus defines both its essence and the nature of its characteristics. Th ...

al consequences of the hypothesis. The positive-instance approach states that an observation sentence is evidence for a universal hypothesis if the sentence describes a positive instance of this hypothesis. The evidential relation can occur in various degrees of strength. These degrees range from direct
proof Proof may refer to: * Proof (truth), argument or sufficient evidence for the truth of a proposition * Alcohol proof, a measure of an alcoholic drink's strength Formal sciences * Formal proof, a construct in proof theory * Mathematical proof, a co ...
of the
truth Truth is the property of being in accord with fact or reality.Merriam-Webster's Online Dictionarytruth 2005 In everyday language, truth is typically ascribed to things that aim to represent reality or otherwise correspond to it, such as beliefs ...

of a hypothesis to weak evidence that is merely consistent with the hypothesis but does not rule out other, competing hypotheses, as in
circumstantial evidence Circumstantial evidence is evidence that relies on an inference Inferences are steps in reasoning, moving from premises to logical consequences; etymologically, the word ''wikt:infer, infer'' means to "carry forward". Inference is theoretical ...

. In
law Law is a system A system is a group of Interaction, interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundari ...
,
rules of evidence The law of evidence, also known as the rules of evidence, encompasses the rules and legal principles that govern the proof of facts in a legal proceeding. These rules determine what evidence must or must not be considered by the trier of ...
govern the types of evidence that are admissible in a legal proceeding. Types of legal evidence include
testimony In law and in religion, testimony is a solemn attestation as to the truth of a matter. Etymology The words "testimony" and "testify" both derive from the Latin word ''testis'', referring to the notion of a disinterested Third-party source, thir ...
,
documentary evidence Documentary evidence is any evidence Evidence for a proposition is what supports this proposition. It is usually understood as an indication that the supported proposition is true. What role evidence plays and how it is conceived varies from f ...
, and
physical evidence Physical evidence (also called real evidence or material evidence) is any material object A bubble of exhaled gas in water In common usage and classical mechanics, a physical object or physical body (or simply an object or body) is a collection ...
. The parts of a legal case that are not in controversy are known, in general, as the "facts of the case." Beyond any facts that are undisputed, a judge or jury is usually tasked with being a
trier of fact A trier of fact, or finder of fact, is a person, or group of persons, who determines what fact A fact is something that is truth, true. The usual test for a statement of fact is verifiability—that is whether it can be demonstrated to corre ...
for the other issues of a case. Evidence and rules are used to decide
questions of factIn law, a question of law, also known as a point of law, is a question that must be answered by applying relevant legal principles to interpretation of the law. Such a question is distinct from a question of fact, which must be answered by reference ...
that are disputed, some of which may be determined by the
legal burden of proof Burden of proof is a legal duty that encompasses two connected but separate ideas that apply for establishing the truth of facts in a trial before tribunals in the United States: the "burden of production" and the "burden of persuasion." In a lega ...
relevant to the case. Evidence in certain cases (e.g.
capital crime Capital punishment, also known as the death penalty, is the state-sanctioned killing of a person as punishment for a crime. The sentence ordering that someone is punished with the death penalty is called a death sentence, and the act of ca ...
s) must be more compelling than in other situations (e.g. minor civil disputes), which drastically affects the quality and quantity of evidence necessary to decide a case.

# Nature of evidence

Evidence for a proposition is what supports this
proposition In logic and linguistics, a proposition is the meaning of a declarative sentence (linguistics), sentence. In philosophy, "Meaning (philosophy), meaning" is understood to be a non-linguistic entity which is shared by all sentences with the same mea ...
. Evidence plays a central role in
epistemology Epistemology (; ) is the concerned with . Epistemologists study the nature, origin, and scope of knowledge, epistemic , the of , and various related issues. Epistemology is considered a major subfield of philosophy, along with other major ...

and in the
philosophy of science Philosophy of science is a branch of philosophy concerned with the foundations, methodology, methods, and implications of science. The central questions of this study concern Demarcation problem, what qualifies as science, the reliability of sc ...
. Reference to evidence is made in many different fields, like in the legal system, in history, in journalism and in everyday discourse. A variety of different attempts have been made to conceptualize the nature of evidence. These attempts often proceed by starting with intuitions from one field or in relation to one theoretical role played by evidence and go on to generalize these intuitions, leading to a universal definition of evidence. One important intuition is that evidence is what justifies
beliefs A belief is an Attitude (psychology), attitude that something is the case, or that some proposition about the world is truth, true. In epistemology, philosophers use the term "belief" to refer to attitudes about the world which can be either tru ...
. This line of thought is usually followed in epistemology and tends to explain evidence in terms of private mental states, for example, as experiences, other beliefs or knowledge. This is closely related to the idea that how
rational Rationality is the quality or state of being rational – that is, being based on or agreeable to reason Reason is the capacity of consciously making sense of things, applying logic Logic (from Ancient Greek, Greek: grc, wikt:λογι ...
someone is, is determined by how they respond to evidence. Another intuition, which is more dominant in the philosophy of science, focuses on evidence as that which confirms scientific hypotheses and arbitrates between competing theories. On this view, it is essential that evidence is public so that different scientists can share the same evidence. This leaves publicly observable phenomena like physical objects and events as the best candidates for evidence, unlike private mental states. One problem with these approaches is that the resulting definitions of evidence, both within a field and between fields, vary a lot and are incompatible with each other. For example, it is not clear what a bloody knife and a perceptual experience have in common when both are treated as evidence in different disciplines. This suggests that there is no unitary concept corresponding to the different theoretical roles ascribed to evidence, i.e. that we do not always mean the same thing when we talk of evidence. Important theorists of evidence include
Bertrand Russell Bertrand Arthur William Russell, 3rd Earl Russell (18 May 1872 – 2 February 1970) was a British , , , , , , , , and .Stanford Encyclopedia of Philosophy"Bertrand Russell" 1 May 2003 Throughout his life, Russell considered himself a , a and ...
,
Willard Van Orman Quine Willard Van Orman Quine (; known to his friends as "Van"; June 25, 1908 – December 25, 2000) was an American philosopher and logician Logic (from Greek: grc, λογική, label=none, lit=possessed of reason Reason is the capacity of ...
, the
logical positivists Logical positivism, later called logical empiricism, and both of which together are also known as neopositivism, was a movement in Western philosophy Western philosophy refers to the philosophy, philosophical thought and work of the Western worl ...
, Timothy Williamson, Earl Conee and Richard Feldman. Russell, Quine and the logical positivists belong to the empiricist tradition and hold that evidence consists in sense data, stimulation of one's sensory receptors and observation statements, respectively. According to Williamson, all and only knowledge constitute evidence. Conee and Feldman hold that only one's current mental states should be considered evidence.

## In epistemology

The guiding intuition within epistemology concerning the role of evidence is that it is what justifies
beliefs A belief is an Attitude (psychology), attitude that something is the case, or that some proposition about the world is truth, true. In epistemology, philosophers use the term "belief" to refer to attitudes about the world which can be either tru ...
. For example, Phoebe's auditory experience of the music justifies her belief that the speakers are on. Evidence has to be possessed by the believer in order to play this role. So Phoebe's own experiences can justify her own beliefs but not someone else's beliefs. Some philosophers hold that evidence possession is restricted to conscious mental states, for example, to sense data. This view has the implausible consequence that many of simple everyday-beliefs would be unjustified. The more common view is that all kinds of mental states, including stored beliefs that are currently unconscious, can act as evidence. It is sometimes argued that the possession of a mental state capable of justifying another is not sufficient for the justification to happen. The idea behind this line of thought is that justified belief has to be connected to or grounded in the mental state acting as its evidence. So Phoebe's belief that the speakers are on is not justified by her auditory experience if the belief is not based in this experience. This would be the case, for example, if Phoebe has both the experience and the belief but is unaware of the fact that the music is produced by the speakers. It is sometimes held that only propositional mental states can play this role, a position known as "propositionalism". A mental state is propositional if it is an attitude directed at a propositional content. Such attitudes are usually expressed by verbs like "believe" together with a that-clause, as in "Robert believes that the corner shop sells milk". Such a view denies that sensory impressions can act as evidence. This is often held as an argument against this view since sensory impressions are commonly treated as evidence. Propositionalism is sometimes combined with the view that only attitudes to true propositions can count as evidence. On this view, the belief that the corner shop sells milk only constitutes evidence for the belief that the corner shop sells dairy products if the corner shop actually sells milk. Against this position, it has been argued that evidence can be misleading but still count as evidence. This line of thought is often combined with the idea that evidence, propositional or otherwise, determines what it is
rational Rationality is the quality or state of being rational – that is, being based on or agreeable to reason Reason is the capacity of consciously making sense of things, applying logic Logic (from Ancient Greek, Greek: grc, wikt:λογι ...
for us to believe. But it can be rational to have a false belief. This is the case when we possess misleading evidence. For example, it was rational for Neo in the Matrix (movie), Matrix movie to believe that he was living in the 20th century because of all the evidence supporting his belief despite the fact that this evidence was misleading since it was part of a simulated reality. This account of evidence and rationality can also be extended to other doxastic attitudes, like disbelief and suspension of belief. So rationality does not just demand that we believe something if we have decisive evidence for it, it also demands that we disbelieve something if we have decisive evidence against it and that we suspend belief if we lack decisive evidence either way.

# Nature of the evidential relation

The term "evidential relation" refers to the relation between evidence and the proposition supported by it. The issue of the nature of the evidential relation concerns the question of what this relation has to be like in order for one thing to justify a belief or to confirm a hypothesis. Important theories in this field include the ''probabilistic approach'', '' hypothetico-deductivism'' and the ''positive-instance approach''. ''Probabilistic approaches'', also referred to as Bayesian epistemology#Confirmation theory, Bayesian confirmation theory, explain the evidential relation in terms of probabilities. They hold that all that is necessary is that the existence of the evidence increases the likelihood that the hypothesis is true. This can be expressed mathematically as $P\left(H \mid E\right) > P\left(H\right)$. In words: a piece of evidence (E) confirms a hypothesis (H) if the conditional probability of this hypothesis relative to the evidence is higher than the unconditional probability of the hypothesis by itself. Smoke (E), for example, is evidence that there is a fire (H), because the two usually occur together, which is why the likelihood of fire given that there is smoke is higher than the likelihood of fire by itself. On this view, evidence is akin to an indicator or a symptom of the truth of the hypothesis. Against this approach, it has been argued that it is too liberal because it allows accidental generalizations as evidence. Finding a nickel in one's pocket, for example, raises the probability of the hypothesis that "All the coins in my pockets are nickels". But, according to Alvin Goldman, it should not be considered evidence for this hypothesis since there is no lawful connection between this one nickel and the other coins in the pocket. ''Hypothetico-deductive model, Hypothetico-deductivism'' is a non-probabilistic approach that characterizes the evidential relations in terms of deductive consequences of the hypothesis. According to this view, "evidence for a hypothesis is a true
observation Observation is the active acquisition of information Information can be thought of as the resolution of uncertainty; it answers the question of "What an entity is" and thus defines both its essence and the nature of its characteristics. Th ...

al consequence of that hypothesis". One problem with the characterization so far is that hypotheses usually contain relatively little information and therefore have few if any deductive observational consequences. So the hypothesis by itself that there is a fire does not entail that smoke is observed. Instead, various auxiliary assumptions have to be included about the location of the smoke, the fire, the observer, the lighting conditions, the laws of chemistry, etc. In this way, the evidential relation becomes a three-place relation between evidence, hypothesis and auxiliary assumptions. This means that whether a thing is evidence for a hypothesis depends on the auxiliary assumptions one holds. This approach fits well with various scientific practices. For example, it is often the case that experimental scientists try to find evidence that would confirm or disconfirm a proposed theory. The hypothetico-deductive approach can be used to predict what should be observed in an experiment if the theory was true. It thereby explains the evidential relation between the experiment and the theory. One problem with this approach is that it cannot distinguish between relevant and certain irrelevant cases. So if smoke is evidence for the hypothesis "there is fire", then it is also evidence for conjunctions including this hypothesis, for example, "there is fire and Socrates was wise", despite the fact that Socrates's wisdom is irrelevant here. According to the ''positive-instance approach'', an observation sentence is evidence for a universal hypothesis if the sentence describes a positive instance of this hypothesis. For example, the observation that "this swan is white" is an instance of the universal hypothesis that "all swans are white". This approach can be given a precise formulation in first-order logic: a proposition is evidence for a hypothesis if it entails the "development of the hypothesis". Intuitively, the development of the hypothesis is what the hypothesis states if it was restricted to only the individuals mentioned in the evidence. In the case above, we have the hypothesis "$\forall x \left(swan\left(x\right) \rightarrow white\left(x\right)\right)$" (all swans are white) which, when restricted to the domain "", containing only the one individual mentioned in the evidence, entails the evidence, i.e. "$swan\left(a\right) \land white\left(a\right)$" (this swan is white). One important shortcoming of this approach is that it requires that the hypothesis and the evidence are formulated in the same vocabulary, i.e. use the same predicates, like "$swan$" or "$white$" above. But many scientific theories posit theoretical objects, like electrons or strings in physics, that are not directly observable and therefore cannot show up in the evidence as conceived here.

# Intellectual evidence (the evident)

The first thing discovered in history is that evidence is related to the senses. A footprint has stayed in the language: the word anchors its origin in the Latin term ''evidential'', which comes from ''videre,'' vision. In this sense, the evidence is what falls under our eyes. Something similar happened in ancient philosophy with Epicurus. He considered all knowledge to be based on sensory perception: if something is perceived by the senses, it is evident, it is always true (cf. Letter to Diogenes Laertius, X, 52). Aristotle went beyond that concept of evidence as the simple passive perception of the senses. He observed that, although all superior animals could have sensory experiences of things, only human beings had to conceptualize them and penetrate more and more into their reality (cf. Metaphysics, 449, b; About the Memory, 452, a; Physics I, c. 1). This certain understanding that the intellect obtains things when it sees them, makes it in an innate and necessary way (it is not something acquired, as can be the habit of science, of which he speaks in Ethics IV). For Aristotle, the evidence is not the merely passive perception of reality, but a gradual process of discoveries, a knowledge that "determines and divides" better and better the "undetermined and undefined": it begins with what is most evident for us, in order to end with what is truer and more evident in nature. Aquinas would later deepen the distinction of evidence ''quad nos'' and ''quad se'' already suggested by Aristotle (cf. ''Summa Th.'' I, q. 2, sol.). Neither of the two understood evidence in purely logical or formal terms, like many schools of thought, tend to understand today. His theory of knowledge proves to be much richer. In philosophical realism, the senses (sight, sound, etc.) provide correct data of what reality is; they do not lie to us unless they are atrophied. When the ''sensitive species'' (or the Aristotelian ''phantom'') formed by the inferior powers is captured by intelligence, it immediately knows and abstracts data from reality; the intelligence with its light, through "study", "determination" and "division" will end up forming concepts, judgments, and reasoning. That first immediate acquisition of reality, devoid of structured reasoning, is the first evidence captured by the intellect. Then the intellect is aware of other obvious truths (such as 2+2=4 or that "the total is greater than or equal to the part") when it compares and relates the previously assimilated knowledge. Scholastic tradition considered that there existed some "primary principles of practical reason", known as immediately and clearly, that could never be broken or repealed. These moral principles would be the most nuclear of natural law. But in addition to those, there would be another part of natural law (formed by deductions or specifications of those principles) that could vary with time and with changing circumstances (cf. ''Summa Th.'' I-II, q. a. 5, sol.). In this way, the natural law would consist of some small immutable principles and enormous variable content. Finnis, Grisez and Boyle point out that what is self-evident cannot be verified by experience, nor derived from any previous knowledge, nor inferred from any basic truth through a middle ground. Immediately they point out that the first principles are evident ''per se nota'', known only through the knowledge of the meanings of the terms, and clarify that "This does not mean that they are mere linguistic clarifications, nor that they are intuitions-insights unrelated to data. Rather, it means that these truths are known (nota) without any middle term (per se), by understanding what is signified by their terms." Then when speaking specifically about the practical principles, they point out that they are not intuitions without contents, but their ''data'' comes from the object to which natural human dispositions tend, that motivate human behavior and guide actions (p. 108). Those goods to which humans primarily tend, which cannot be "reduced" to another good (it is to say, that they are not means to an end), they are considered "evident": "as the basic good are reasons with no further reasons" (p. 110). George Orwell (2009) considered that one of the principal duties of today's world is to recover what is obvious. Actually, when the manipulation of language for political ends grows strongly, when "war is peace", "freedom is slavery", "ignorance is strength", it is important to rediscover the basic principles of the reason. Riofrio has designed a method to validate which ideas, principles or reasons can be considered "evident", testing in that ideas all the ten characteristics of the evident things.

# Empirical 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 or other controlled conditions. Scientific evidence usually goes towards supporting or rejecting a hypothesis. The burden of proof is on the person making a contentious claim. Within science, this translates to the burden resting on presenters of a paper, in which the presenters argue 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 is the hypothesis 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.

# Law

In law, the production and presentation of evidence depend first on establishing on whom the Legal burden of proof, burden of proof lies. Admissible evidence is that which a court receives and considers for the purposes of deciding a particular case. Two primary burden-of-proof considerations exist in law. The first is on whom the burden rests. In many, especially Western, courts, the burden of proof is placed on the prosecution in criminal cases and the plaintiff in civil cases. The second consideration is the degree of certitude proof must reach, depending on both the quantity and quality of evidence. These degrees are different for criminal and civil cases, the former requiring evidence beyond a reasonable doubt, the latter considering only which side has the preponderance of evidence, or whether the proposition is more likely true or false. The decision-maker, often a jury, but sometimes a judge decides whether the burden of proof has been fulfilled. After deciding who will carry the burden of proof, the evidence is first gathered and then presented before the court:

## Collection

In a criminal investigation, rather than attempting to prove an abstract or hypothetical point, the evidence gatherers attempt to determine who is responsible for a Crime, criminal act. The focus of criminal evidence is to connect physical evidence and reports of witnesses to a specific person.

## Presentation

The path that physical evidence takes from the scene of a crime or the arrest of a suspect to the courtroom is called the chain of custody. In a criminal case, this path must be clearly documented or attested to by those who handled the evidence. If the chain of evidence is broken, a defendant may be able to persuade the judge to declare the evidence Admissible evidence, inadmissible. Presenting evidence before the court differs from the gathering of evidence in important ways. Gathering evidence may take many forms; presenting evidence that tends to prove or disprove the point at issue is strictly governed by rules. Failure to follow these rules leads 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 the United States, evidence in federal court is admitted or excluded under the Federal Rules of Evidence.

## Burden of proof

The ''burden of proof'' is the obligation of a party in an argument or dispute to provide sufficient evidence to shift the other party's or a third party's belief from their initial position. The burden of proof must be fulfilled by both establishing confirming evidence and negating oppositional evidence. Conclusions drawn from evidence may be subject to criticism based on a perceived failure to fulfill the burden of proof. Two principal considerations are: # On whom does the burden of proof rest? # To what degree of certitude must the assertion be supported? The latter question depends on the nature of the point under contention and determines the quantity and quality of evidence required to meet the burden of proof. In a criminal procedure, criminal trial in the United States, for example, the Prosecutor, prosecution carries the burden of proof since the defendant is Presumption of innocence, presumed innocent until proven guilty Reasonable doubt, beyond a reasonable doubt. Similarly, in most civil procedures, the plaintiff carries the burden of proof and must convince a judge or jury that the preponderance of the evidence is on their side. Other legal standards of proof include "reasonable suspicion", "probable cause" (as for arrest), "''prima facie'' evidence", "credible evidence", "substantial evidence", and "clear and convincing evidence". In a philosophical debate, there is an implicit burden of proof on the party asserting a claim, since the default position is generally one of neutrality or unbelief. Each party in a debate will therefore carry the burden of proof for any assertion they make in the argument, although some assertions may be granted by the other party without further evidence. If the debate is set up as a resolution (law), resolution to be supported by one side and refuted by another, the overall burden of proof is on the side supporting the resolution.

# Types

*Digital evidence *Personal experience *Physical evidence *Relationship evidence *Scientific evidence *Testimony, Testimonial evidence *Trace evidence