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Evidence for a
proposition In logic and linguistics, a proposition is the meaning of a declarative sentence. In philosophy, " meaning" is understood to be a non-linguistic entity which is shared by all sentences with the same meaning. Equivalently, a proposition is the no ...
is what supports this proposition. It is usually understood as an indication that the supported proposition is
true True most commonly refers to truth, the state of being in congruence with fact or reality. True may also refer to: Places * True, West Virginia, an unincorporated community in the United States * True, Wisconsin, a town in the United States * ...
. What role evidence plays and how it is conceived varies from field to field. In
epistemology Epistemology (; ), or the theory of knowledge, is the branch of philosophy concerned with knowledge. Epistemology is considered a major subfield of philosophy, along with other major subfields such as ethics, logic, and metaphysics. Episte ...
, evidence is what justifies
beliefs A belief is an attitude that something is the case, or that some proposition is true. In epistemology, philosophers use the term "belief" to refer to attitudes about the world which can be either true or false. To believe something is to tak ...
or what makes it
rational Rationality is the quality of being guided by or based on reasons. In this regard, a person acts rationally if they have a good reason for what they do or a belief is rational if it is based on strong evidence. This quality can apply to an abi ...
to hold a certain
doxastic Doxastic logic is a type of logic concerned with reasoning about beliefs. The term ' derives from the Ancient Greek (''doxa'', "opinion, belief"), from which the English term ''doxa'' ("popular opinion or belief") is also borrowed. Typically, a d ...
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. In
phenomenology Phenomenology may refer to: Art * Phenomenology (architecture), based on the experience of building materials and their sensory properties Philosophy * Phenomenology (philosophy), a branch of philosophy which studies subjective experiences and ...
, evidence is understood in a similar sense. Here, however, it is limited to intuitive knowledge that provides immediate access to truth and is therefore indubitable. In this role, it is supposed to provide ultimate justifications for basic philosophical principles and thus turn
philosophy Philosophy (from , ) is the systematized study of general and fundamental questions, such as those about existence, reason, Epistemology, knowledge, Ethics, values, Philosophy of mind, mind, and Philosophy of language, language. Such quest ...
into a rigorous science. However, it is highly controversial whether evidence can meet these requirements. Other fields, including the
science Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence for ...
s and the
law Law is a set of rules that are created and are enforceable by social or governmental institutions to regulate behavior,Robertson, ''Crimes against humanity'', 90. with its precise definition a matter of longstanding debate. It has been vari ...
, tend to emphasize more the public nature of evidence (for example, scientists tend to focus on how the data used during
statistical inference Statistical inference is the process of using data analysis to infer properties of an underlying distribution of probability.Upton, G., Cook, I. (2008) ''Oxford Dictionary of Statistics'', OUP. . Inferential statistical analysis infers properti ...
are generated). In
philosophy of science Philosophy of science is a branch of philosophy concerned with the foundations, methods, and implications of science. The central questions of this study concern what qualifies as science, the reliability of scientific theories, and the ult ...
, evidence is understood as that which '' confirms'' or ''disconfirms'' scientific hypotheses. Measurements of Mercury's "anomalous"
orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such ...
, for example, are seen as evidence that confirms
Einstein Albert Einstein ( ; ; 14 March 1879 – 18 April 1955) was a German-born theoretical physicist, widely acknowledged to be one of the greatest and most influential physicists of all time. Einstein is best known for developing the theor ...
's
theory of general relativity General relativity, also known as the general theory of relativity and Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics. G ...
. 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 method for acquiring knowledge that has characterized the development of science since at least the 17th century (with notable practitioners in previous centuries; see the article history of scientific ...
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 In the philosophy of science, observations are said to be "theory-laden" when they are affected by the theoretical presuppositions held by the investigator. The thesis of theory-ladenness is most strongly associated with the late 1950s and early 1 ...
, 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 is evidence, i.e. what supports or counters this proposition, that is constituted by or accessible to sense experience or experimental procedure. Empirical evidence is of central importance to the sciences a ...
'' 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. In
philosophy Philosophy (from , ) is the systematized study of general and fundamental questions, such as those about existence, reason, Epistemology, knowledge, Ethics, values, Philosophy of mind, mind, and Philosophy of language, language. Such quest ...
, this is referred to as the "evidential relation" and 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 The hypothetico-deductive model or method is a proposed description of the scientific method. According to it, scientific inquiry proceeds by formulating a hypothesis in a form that can be falsifiable, using a test on observable data where the out ...
, evidence consists in
observation Observation is the active acquisition of information from a primary source. In living beings, observation employs the senses. In science, observation can also involve the perception and recording of data via the use of scientific instruments ...
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 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 belie ...
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 to connect it to a conclusion of fact—such as a fingerprint at the scene of a crime. By contrast, direct evidence supports the truth of an assertion directly—i.e., without need ...
. In
law Law is a set of rules that are created and are enforceable by social or governmental institutions to regulate behavior,Robertson, ''Crimes against humanity'', 90. with its precise definition a matter of longstanding debate. It has been vari ...
,
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 f ...
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 witness. ...
,
documentary evidence Documentary evidence is any evidence that is, or can be, introduced at a trial in the form of documents, as distinguished from oral testimony. Documentary evidence is most widely understood to refer to writings on paper (such as an invoice, a con ...
, and
physical evidence In evidence law, physical evidence (also called real evidence or material evidence) is any material object that plays some role in the matter that gave rise to the litigation, introduced as evidence in a judicial proceeding (such as a trial) to ...
. 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 who determines which facts are available in a legal proceeding (usually a trial) and how relevant they are to deciding its outcome. To determine a fact is to decide, from the evidence present ...
for the other issues of a case. Evidence and rules are used to decide questions of fact that are disputed, some of which may be determined by the
legal burden of proof In a legal dispute, one party has the burden of proof to show that they are correct, while the other party had no such burden and is presumed to be correct. The burden of proof requires a party to produce evidence to establish the truth of facts ...
relevant to the case. Evidence in certain cases (e.g.
capital crime Capital punishment, also known as the death penalty, is the state-sanctioned practice of deliberately killing a person as a punishment for an actual or supposed crime, usually following an authorized, rule-governed process to conclude that t ...
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

Understood in its broadest sense, evidence for a
proposition In logic and linguistics, a proposition is the meaning of a declarative sentence. In philosophy, " meaning" is understood to be a non-linguistic entity which is shared by all sentences with the same meaning. Equivalently, a proposition is the no ...
is what supports this proposition. Traditionally, the term is sometimes understood in a narrower sense: as the intuitive knowledge of facts that are considered indubitable. In this sense, only the singular form is used. This meaning is found especially in phenomenology, in which evidence is elevated to one of the basic principles of philosophy, giving philosophy the ultimate justifications that are supposed to turn it into a rigorous science. In a more modern usage, the plural form is also used. In academic discourse, evidence plays a central role in
epistemology Epistemology (; ), or the theory of knowledge, is the branch of philosophy concerned with knowledge. Epistemology is considered a major subfield of philosophy, along with other major subfields such as ethics, logic, and metaphysics. Episte ...
and in the
philosophy of science Philosophy of science is a branch of philosophy concerned with the foundations, methods, and implications of science. The central questions of this study concern what qualifies as science, the reliability of scientific theories, and the ult ...
. Reference to evidence is made in many different fields, like in science, 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 that something is the case, or that some proposition is true. In epistemology, philosophers use the term "belief" to refer to attitudes about the world which can be either true or false. To believe something is to tak ...
. 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 of being guided by or based on reasons. In this regard, a person acts rationally if they have a good reason for what they do or a belief is rational if it is based on strong evidence. This quality can apply to an abi ...
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 mathematician, philosopher, logician, and public intellectual. He had a considerable influence on mathematics, logic, set theory, linguistics, a ...
,
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 in the analytic tradition, recognized as "one of the most influential philosophers of the twentieth century ...
, the
logical positivists Logical positivism, later called logical empiricism, and both of which together are also known as neopositivism, is a movement in Western philosophy whose central thesis was the verification principle (also known as the verifiability criterion o ...
,
Timothy Williamson Timothy Williamson (born 1955) is a British philosopher whose main research interests are in philosophical logic, philosophy of language, epistemology and metaphysics. He is the Wykeham Professor of Logic at the University of Oxford, and fe ...
, 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 that something is the case, or that some proposition is true. In epistemology, philosophers use the term "belief" to refer to attitudes about the world which can be either true or false. To believe something is to tak ...
. 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 of being guided by or based on reasons. In this regard, a person acts rationally if they have a good reason for what they do or a belief is rational if it is based on strong evidence. This quality can apply to an abi ...
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 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.

## In phenomenology

The meaning of the term "evidence" in phenomenology shows many parallels to its epistemological usage, but it is understood in a narrower sense. Thus, evidence here specifically refers to intuitive knowledge, which is described as "self-given" (). This contrasts with empty intentions, in which one refers to states of affairs through a certain opinion, but without an intuitive presentation. This is why evidence is often associated with the controversial thesis that it constitutes an immediate access to truth. In this sense, the evidently given phenomenon guarantees its own truth and is therefore considered indubitable. Due to this special epistemological status of evidence, it is regarded in phenomenology as the basic principle of all philosophy. In this form, it represents the lowest foundation of knowledge, which consists of indubitable insights upon which all subsequent knowledge is built. This evidence-based method is meant to make it possible for philosophy to overcome many of the traditionally unresolved disagreements and thus become a rigorous science. This far-reaching claim of phenomenology, based on absolute certainty, is one of the focal points of criticism by its opponents. Thus, it has been argued that even knowledge based on self-evident intuition is fallible. This can be seen, for example, in the fact that even among phenomenologists, there is much disagreement about the basic structures of experience.

## In philosophy of science

In the sciences, evidence is understood as what '' confirms'' or ''disconfirms'' scientific hypotheses. The term "confirmation" is sometimes used synonymously with that of "evidential support". Measurements of Mercury's "anomalous" orbit, for example, are seen as evidence that confirms Einstein's theory of general relativity. This is especially relevant for choosing between competing theories. So in the case above, evidence plays the role of ''neutral arbiter'' between Newton's and Einstein's theory of gravitation. This is only possible if scientific evidence is ''public'' and ''uncontroversial'' so that proponents of competing scientific theories agree on what evidence is available. These requirements suggest scientific evidence consists not of ''private mental states'' but of ''public physical objects or events''. It is often held that evidence is in some sense prior to the hypotheses it confirms. This was sometimes understood as ''temporal priority'', i.e. that we come first to possess the evidence and later form the hypothesis through induction. But this temporal order is not always reflected in scientific practice, where experimental researchers may look for a specific piece of evidence in order to confirm or disconfirm a pre-existing hypothesis.
Logical positivists Logical positivism, later called logical empiricism, and both of which together are also known as neopositivism, is a movement in Western philosophy whose central thesis was the verification principle (also known as the verifiability criterion o ...
, on the other hand, held that this priority is ''semantic'' in nature, i.e. that the meanings of the theoretical terms used in the hypothesis are determined by what would count as evidence for them. Counterexamples for this view come from the fact that our idea of what counts as evidence may change while the meanings of the corresponding theoretical terms remain constant. The most plausible view is that this priority is ''epistemic'' in nature, i.e. that our belief in a hypothesis is justified based on the evidence while the justification for the belief in the evidence does not depend on the hypothesis. A central issue for the scientific conception of evidence is the problem of underdetermination, i.e. that the evidence available supports competing theories equally well. So, for example, evidence from our everyday life about how gravity works confirms Newton's and Einstein's theory of gravitation equally well and is therefore unable to establish consensus among scientists. But in such cases, it is often the gradual accumulation of evidence that eventually leads to an emerging consensus. This evidence-driven process towards consensus seems to be one hallmark of the sciences not shared by other fields. Another problem for the conception of evidence in terms of confirmation of hypotheses is that what some scientists consider the evidence to be may already involve various theoretical assumptions not shared by other scientists. This phenomenon is known as
theory-ladenness In the philosophy of science, observations are said to be "theory-laden" when they are affected by the theoretical presuppositions held by the investigator. The thesis of theory-ladenness is most strongly associated with the late 1950s and early 1 ...
. Some cases of theory-ladenness are relatively uncontroversial, for example, that the numbers output by a measurement device need additional assumptions about how this device works and what was measured in order to count as meaningful evidence. Other putative cases are more controversial, for example, the idea that different people or cultures perceive the
world In its most general sense, the term "world" refers to the totality of entities, to the whole of reality or to everything that is. The nature of the world has been conceptualized differently in different fields. Some conceptions see the wor ...
through different, incommensurable conceptual schemes, leading them to very different impressions about what is the case and what evidence is available. Theory-ladenness threatens to impede the role of evidence as neutral arbiter since these additional assumptions may favor some theories over others. It could thereby also undermine a consensus to emerge since the different parties may be unable to agree even on what the evidence is. When understood in the widest sense, it is not controversial that some form of theory-ladenness exists. But it is questionable whether it constitutes a serious threat to scientific evidence when understood in this sense.

# Nature of the evidential relation

Philosopher A philosopher is a person who practices or investigates philosophy. The term ''philosopher'' comes from the grc, φιλόσοφος, , translit=philosophos, meaning 'lover of wisdom'. The coining of the term has been attributed to the Greek th ...
s in the 20th century started to investigate the "evidential relation", 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 The hypothetico-deductive model or method is a proposed description of the scientific method. According to it, scientific inquiry proceeds by formulating a hypothesis in a form that can be falsifiable, using a test on observable data where the out ...
'' and the ''positive-instance approach''. ''Probabilistic approaches'', also referred to as 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 Alvin Ira Goldman (born 1938) is an American philosopher who is Emeritus Board of Governors Professor of Philosophy and Cognitive Science at Rutgers University in New Jersey and a leading figure in epistemology. Education and career Goldman ea ...
, 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-deductivism The hypothetico-deductive model or method is a proposed description of the scientific method. According to it, scientific inquiry proceeds by formulating a hypothesis in a form that can be falsifiable, using a test on observable data where the out ...
'' 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 from a primary source. In living beings, observation employs the senses. In science, observation can also involve the perception and recording of data via the use of scientific instruments ...
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 First-order logic—also known as predicate logic, quantificational logic, and first-order predicate calculus—is a collection of formal systems used in mathematics, philosophy, linguistics, and computer science. First-order logic uses quantifi ...
: 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.

# 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
experiment An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried. Experiments provide insight into cause-and-effect by demonstrating what outcome occurs whe ...
s in a
laboratory A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratory services are provided in a variety of settings: physi ...
or other controlled conditions. Scientists tend to focus on how the data used during
statistical inference Statistical inference is the process of using data analysis to infer properties of an underlying distribution of probability.Upton, G., Cook, I. (2008) ''Oxford Dictionary of Statistics'', OUP. . Inferential statistical analysis infers properti ...
are generated.
Scientific evidence Scientific evidence is evidence that serves to either support or counter a scientific theory or hypothesis, although scientists also use evidence in other ways, such as when applying theories to practical problems. "Discussions about empirical ev ...
usually goes towards supporting or rejecting a
hypothesis A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous o ...
. 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 Bias is a disproportionate weight ''in favor of'' or ''against'' an idea or thing, usually in a way that is closed-minded, prejudicial, or unfair. Biases can be innate or learned. People may develop biases for or against an individual, a group ...
inherent to
anecdotal evidence Anecdotal evidence is evidence based only on personal observation, collected in a casual or non-systematic manner. The term is sometimes used in a legal context to describe certain kinds of testimony which are uncorroborated by objective, independ ...
. Nina Teiholz and Eric Bass propose a ranking system for forms of empirical evidence in the field of medicine. According to their view,
systematic review A systematic review is a scholarly synthesis of the evidence on a clearly presented topic using critical methods to identify, define and assess research on the topic. A systematic review extracts and interprets data from published studies on t ...
s are the best source, followed by control trials and
observational studies In fields such as epidemiology, social sciences, psychology and statistics, an observational study draws inferences from a sample to a population where the independent variable is not under the control of the researcher because of ethical conc ...
with expert opinion on the lowest level.

# Law

In law, the production and presentation of evidence depend first on establishing on whom the burden of proof lies.
Admissible evidence Admissible evidence, in a court of law, is any testimonial, documentary, or tangible evidence that may be introduced to a factfinder—usually a judge or jury—to establish or to bolster a point put forth by a party to the proceeding. For ...
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 Beyond a reasonable doubt is a legal standard of proof required to validate a criminal conviction in most adversarial legal systems. It is a higher standard of proof than the balance of probabilities standard commonly used in civil cases, be ...
, 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
criminal In ordinary language, a crime is an unlawful act punishable by a state or other authority. The term ''crime'' does not, in modern criminal law, have any simple and universally accepted definition,Farmer, Lindsay: "Crime, definitions of", in C ...
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 Chain of custody (CoC), in legal contexts, is the chronological documentation or paper trail that records the sequence of custody, control, transfer, analysis, and disposition of materials, including physical or electronic evidence. Of particular ...
. 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 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 trial Criminal procedure is the adjudication process of the criminal law. While criminal procedure differs dramatically by jurisdiction, the process generally begins with a formal criminal charge with the person on trial either being free on bail or ...
in the United States, for example, the
prosecution A prosecutor is a legal representative of the prosecution in states with either the common law adversarial system or the civil law inquisitorial system. The prosecution is the legal party responsible for presenting the case in a criminal tr ...
carries the burden of proof since the
defendant In court proceedings, a defendant is a person or object who is the party either accused of committing a crime in criminal prosecution or against whom some type of civil relief is being sought in a civil case. Terminology varies from one ju ...
is presumed innocent until proven guilty beyond a reasonable doubt. Similarly, in most
civil procedure Civil procedure is the body of law that sets out the rules and standards that courts follow when adjudicating civil lawsuits (as opposed to procedures in criminal law matters). These rules govern how a lawsuit or case may be commenced; what kin ...
s, the
plaintiff A plaintiff ( Π in legal shorthand) is the party who initiates a lawsuit (also known as an ''action'') before a court. By doing so, the plaintiff seeks a legal remedy. If this search is successful, the court will issue judgment in favor of ...
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 An arrest is the act of apprehending and taking a person into custody (legal protection or control), usually because the person has been suspected of or observed committing a crime. After being taken into custody, the person can be questi ...
), "''
prima facie ''Prima facie'' (; ) is a Latin expression meaning ''at first sight'' or ''based on first impression''. The literal translation would be 'at first face' or 'at first appearance', from the feminine forms of ''primus'' ('first') and ''facies'' (' ...
'' evidence", "credible evidence", "substantial evidence", and "clear and convincing evidence". In a philosophical
debate Debate is a process that involves formal discourse on a particular topic, often including a moderator and audience. In a debate, arguments are put forward for often opposing viewpoints. Debates have historically occurred in public meetings, ...
, 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 Resolution(s) may refer to: Common meanings * Resolution (debate), the statement which is debated in policy debate * Resolution (law), a written motion adopted by a deliberative body * New Year's resolution, a commitment that an individual ma ...
to be supported by one side and refuted by another, the overall burden of proof is on the side supporting the resolution.

# Specific types of evidence

* Digital evidence * Personal experience *
Physical evidence In evidence law, physical evidence (also called real evidence or material evidence) is any material object that plays some role in the matter that gave rise to the litigation, introduced as evidence in a judicial proceeding (such as a trial) to ...
* Relationship evidence *
Scientific evidence Scientific evidence is evidence that serves to either support or counter a scientific theory or hypothesis, although scientists also use evidence in other ways, such as when applying theories to practical problems. "Discussions about empirical ev ...
* Testimonial evidence *
Trace evidence Trace evidence is created when objects make contact. The material is often transferred by heat or induced by contact friction. The importance of trace evidence in criminal investigations was shown by Dr. Edmond Locard in the early 20th century. ...

*
Argument An argument is a statement or group of statements called premises intended to determine the degree of truth or acceptability of another statement called conclusion. Arguments can be studied from three main perspectives: the logical, the dialecti ...
*
Belief A belief is an attitude that something is the case, or that some proposition is true. In epistemology, philosophers use the term "belief" to refer to attitudes about the world which can be either true or false. To believe something is to tak ...
*
Empiricism In philosophy, empiricism is an epistemological theory that holds that knowledge or justification comes only or primarily from sensory experience. It is one of several views within epistemology, along with rationalism and skepticism. Empir ...
* Evidence packaging *
Falsifiability Falsifiability is a standard of evaluation of scientific theories and hypotheses that was introduced by the philosopher of science Karl Popper in his book '' The Logic of Scientific Discovery'' (1934). He proposed it as the cornerstone of a ...
*
Logical positivism Logical positivism, later called logical empiricism, and both of which together are also known as neopositivism, is a movement in Western philosophy whose central thesis was the verification principle (also known as the verifiability criterion o ...
*
Mathematical proof A mathematical proof is an inferential argument for a mathematical statement, showing that the stated assumptions logically guarantee the conclusion. The argument may use other previously established statements, such as theorems; but every pr ...
*
Proof (truth) A proof is sufficient evidence or a sufficient argument for the truth of a proposition. The concept applies in a variety of disciplines, with both the nature of the evidence or justification and the criteria for sufficiency being area-dependen ...
*
Reason Reason is the capacity of consciously applying logic by drawing conclusions from new or existing information, with the aim of seeking the truth. It is closely associated with such characteristically human activities as philosophy, science, lang ...
* Skepticism *
Theory of justification Justification (also called epistemic justification) is the property of belief that qualifies it as knowledge rather than mere opinion. Epistemology is the study of reasons that someone holds a rationally admissible belief (although the term is a ...
*
Validity (logic) In logic, specifically in deductive reasoning, an argument is valid if and only if it takes a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false. It is not required for a valid argument to h ...

# References

* * * * *
ASTM ASTM International, formerly known as American Society for Testing and Materials, is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, a ...
E141 Standard Practice for Acceptance of Evidence Based on the Results of Probability Sampling * {{Use dmy dates, date=March 2018 Concepts in epistemology