Concept

Certainty

Overview

Certainty (also known as epistemic certainty or objective certainty) is the epistemic property of beliefs which a person has no rational grounds for doubting. One standard way of defining epistemic certainty is that a belief is certain if and only if the person holding that belief could not be mistaken in holding that belief. Other common definitions of certainty involve the indubitable nature of such beliefs or define certainty as a property of those beliefs with the greatest possible justification. Certainty is closely related to knowledge, although contemporary philosophers tend to treat knowledge as having lower requirements than certainty.

Importantly, epistemic certainty is not the same thing as psychological certainty (also known as subjective certainty or certitude), which describes the highest degree to which a person could be convinced that something is true. While a person may be completely convinced that a particular belief is true, and might even be psychologically incapable of entertaining its falsity, this does not entail that the belief is itself beyond rational doubt or incapable of being false. While the word "certainty" is sometimes used to refer to a person's subjective certainty about the truth of a belief, philosophers are primarily interested in the question of whether any beliefs ever attain objective certainty.

The philosophical question of whether one can ever be truly certain about anything has been widely debated for centuries. Many proponents of philosophical skepticism deny that certainty is possible, or claim that it is only possible in a priori domains such as logic or mathematics. Historically, many philosophers have held that knowledge requires epistemic certainty, and therefore that one must have infallible justification in order to count as knowing the truth of a proposition. However, many philosophers such as René Descartes were troubled by the resulting skeptical implications, since all of our experiences at least seem to be compatible with various skeptical scenarios. It is generally accepted today that most of our beliefs are compatible with their falsity and are therefore fallible, although the status of being certain is still often ascribed to a limited range of beliefs (such as "I exist"). The apparent fallibility of our beliefs has led many contemporary philosophers to deny that knowledge requires certainty.

Overview adapted from Wikipedia (CC BY-SA 4.0; see the article history for authors).

In the original texts

Passages from public-domain books where Certainty is discussed.

Certainty is when the direction is not only true for the most part, but infallible. Liberty is when the direction is not restrained to some definite means, but comprehendeth all the means and ways possible; for the poet saith well SAPIENTIBUS UNDIQUE LATAE SUNT VIAE, and where there is the greatest…
Francis Bacon, Valerius Terminus
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Love of certainty is a demand for guarantees in advance of action. Ignoring the fact that truth can be bought only by the adventure of experiment, dogmatism turns truth into an insurance company.
John Dewey, Human Nature and Conduct
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The point is that on this ground certainty is completely inseparable from truth: but the confession is to be regarded as the very acmé of certainty-giving which in its nature is subjective. The final decision therefore lies with the confession. To this therefore the accused has an absolute right, if the proof is to be made final and the judges to be convinced.
Georg Wilhelm Friedrich Hegel, Hegel's Philosophy of Mind
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CCVI. That we possess even more than a moral certainty of it. Besides, there are some, even among natural, things which we judge to be absolutely certain. [Absolute certainty arises when we judge that it is impossible a thing can be otherwise than as we think it]. This certainty is founded on the metaphysical ground, that, as God is supremely good and the source of all truth, the faculty of distinguishing truth from…
René Descartes, Selections from the Principles of Philosophy
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Our subjective certainty is usually a result of habit, and may lead us astray in circumstances which are unusual in ways of which we are unaware. For such reasons, no form of self-evidence seems to afford an absolute criterion of truth.
Bertrand Russell, The Analysis of Mind
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Philosophers who discussed Certainty

Related ideas

Opposing perspectives

Philosophical realism

Place in the tradition

Part of Agnosticism.

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