kb/data/en.wikipedia.org/wiki/Evidence-1.md

title	chunk	source	category	tags	date_saved	instance
Evidence	2/5	https://en.wikipedia.org/wiki/Evidence	reference	science, encyclopedia	2026-05-05T09:55:48.385077+00:00	kb-cron

The evident instills certainty and grants the knower a subjective sense of security, as they believe to have aligned with the truth Initially, evident truths are perceived as natural and effortless, as Aristotle highlighted. They are innately present within the intellect, fostering a peaceful and harmonious understanding. Consequently, evident truths appear to be widely shared, strongly connected to common sense, which comprises generally accepted beliefs. Evident truths are fertile ground: they provide a solid foundation for other branches of scientific knowledge to flourish. These ten characteristics of what is evident allowed Riofrio to formulate a test of evidence to detect the level of certainty or evidence that one argument or proof could have.

=== Evidential relation === Philosophers 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 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
    (
    H
    ∣
    E
    )
    >
    P
    (
    H
    )
  

{\displaystyle P(H\mid E)>P(H)}

. 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-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 observational 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 "

    ∀
    x
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    w
    a
    n
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    →
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{\displaystyle \forall x(swan(x)\rightarrow white(x))}

" (all swans are white) which, when restricted to the domain "{a}", containing only the one individual mentioned in the evidence, entails the evidence, i.e. "

    s
    w
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    n
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    a
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    ∧
    w
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    i
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{\displaystyle swan(a)\land white(a)}

" (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 "

    s
    w
    a
    n
  

{\displaystyle swan}

" or "

    w
    h
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    t
    e
  

{\displaystyle 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.

=== In specific fields === Important theorists of evidence include Bertrand Russell, Willard Van Orman Quine, the logical positivists, 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.