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Infinitism is the view that knowledge may be justified by an infinite chain of reasons. It belongs to epistemology, the branch of philosophy that considers the possibility, nature, and means of knowledge.

Epistemology A branch of philosophy concerned with the nature and scope of knowledge

Epistemology is the branch of philosophy concerned with the theory of knowledge.

Philosophy intellectual and/or logical study of general and fundamental problems

Philosophy is the study of general and fundamental questions about existence, knowledge, values, reason, mind, and language. Such questions are often posed as problems to be studied or resolved. The term was probably coined by Pythagoras. Philosophical methods include questioning, critical discussion, rational argument, and systematic presentation. Classic philosophical questions include: Is it possible to know anything and to prove it? What is most real? Philosophers also pose more practical and concrete questions such as: Is there a best way to live? Is it better to be just or unjust? Do humans have free will?

Knowledge is a familiarity, awareness, or understanding of someone or something, such as facts, information, descriptions, or skills, which is acquired through experience or education by perceiving, discovering, or learning.


Epistemological infinitism

Since Gettier, "knowledge" is no longer widely accepted as meaning "justified true belief" only. [1] However, some epistemologists[ who? ] still consider knowledge to have a justification condition. Traditional theories of justification (foundationalism and coherentism) and indeed some philosophers[ who? ] consider an infinite regress not to be a valid justification. In their view, if A is justified by B, B by C, and so forth, then either

The Gettier problem, in the field of epistemology, is a landmark philosophical problem concerning our understanding of descriptive knowledge. Attributed to American philosopher Edmund Gettier, Gettier-type counterexamples challenge the long-held justified true belief (JTB) account of knowledge. The JTB account holds that knowledge is equivalent to justified true belief; if all three conditions are met of a given claim, then we have knowledge of that claim. In his 1963 three-page paper titled "Is Justified True Belief Knowledge?", Gettier attempts to illustrate by means of two counterexamples that there are cases where individuals can have a justified, true belief regarding a claim but still fail to know it because the reasons for the belief, while justified, turn out to be false. Thus, Gettier claims to have shown that the JTB account is inadequate; that it does not account for all of the necessary and sufficient conditions for knowledge.

Foundationalism concerns philosophical theories of knowledge resting upon justified belief, or some secure foundation of certainty such as a conclusion inferred from a basis of sound premises. The main rival of the foundationalist theory of justification is the coherence theory of justification, whereby a body of knowledge, not requiring a secure foundation, can be established by the interlocking strength of its components, like a puzzle solved without prior certainty that each small region was solved correctly.

Coherentism is the name given to a few philosophical theories in modern epistemology.

  1. The chain must end with a link that requires no independent justification (a foundation),
  2. The chain must come around in a circle in some finite number of steps (the belief may be justified by its coherence), or
  3. Our beliefs must not be justified after all (as is posited by philosophical skeptics).

Infinitism, the view, for example, of Peter D. Klein, challenges this consensus, referring back to work of Paul Moser (1984) and John Post (1987). [2] In this view, the evidential ancestry of a justified belief must be infinite and non-repeating, which follows from the conjunction two principles that Klein sees as having straightforward intuitive appeal: "The Principle of Avoiding Circularity" and "The Principle of Avoiding Arbitrariness."

Peter David Klein is a philosopher specializing in issues in epistemology. Peter Klein received a BA at Earlham College (1962), and an MA (1964) and PhD from Yale University (1966).

Paul Moser American philosopher

Paul K. Moser is an American philosopher who writes on epistemology and the philosophy of religion. He is Professor of Philosophy at Loyola University Chicago and past editor of the American Philosophical Quarterly. He is the author of many works in epistemology and the philosophy of religion, in which he has supported versions of epistemic foundationalism and volitional theism. His work brings these two positions together to support volitional evidentialism about theistic belief, in contrast to fideism and traditional natural theology. He draws from some epistemological and theological insights of the apostle Paul, Kierkegaard, P.T. Forsyth, H.R. Mackintosh, and H. H. Farmer, but he adds (i) a notion of purposively available evidence of God’s existence, (ii) a notion of authoritative evidence in contrast with spectator evidence, (iii) a notion of personifying evidence of God whereby some willing humans become salient evidence of God's existence, and (iv) a notion of convictional knowledge of divine reality. His most recent work emphasizes the importance of experiential foundational evidence from the self-manifestation of God's moral character to cooperative humans, particularly in moral conscience. An evidential role for experienced agapē, along the lines of Romans 5:5, is central to his theistic epistemology, as is his view that God is self-authenticating or self-evidencing via self-manifestation and conviction toward unselfish love. One result is a distinctive approach to divine hiddenness and the evidence for God's reality and presence.

The Principle of Avoiding Circularity (PAC) is stated as follows: "For all x, if a person, S, has a justification for x, then for all y, if y is in the evidential ancestry of x for S, then x is not in the evidential ancestry of y for S." [3] PAC says that the proposition to be justified cannot be a member of its own evidential ancestry, which is violated by coherence theories of justification.

The Principle of Avoiding Arbitrariness (PAA) is stated as follows: "For all x, if a person, S, has a justification for x, then there is some reason, r1, available to S for x; and there is some reason, r2, available to S for r1; etc." [4] PAA says that in order to avoid arbitrariness, for any proposition x to be justified for an epistemological agent, there must be some reason r available to the agent; this reason will in turn require the same structure of justification, and so on ad infinitum. Foundationalist theories can only avoid arbitrariness by claiming that some propositions are self-justified. But if a proposition is its own justification (e.g. coherentism), then it is a member of its own evidential ancestry, and the structure of justification is circular.

In this view, the conjunction of both PAC and PAA leaves infinitism as the only alternative to skepticism. [5]

The Availability of Reasons: Klein also relies on the notion of "availability". In other words, a reason must be available to the subject in order for it to be a candidate for justification. There are two conditions that need to be satisfied in order for a reason to be available: objectively and subjectively.

An objectively available reason is stated as follows: "a belief, r, is objectively available to S as a reason for p if (1) r has some sufficiently high probability and the conditional probability of p given r is sufficiently high; or (2) an impartial, informed observer would accept r as a reason for p; or (3) r would be accepted in the long run by an appropriately defined set of people; or (4) r is evident for S and r makes p evident for S; or (5) r accords with S's deepest epistemic commitments; or (6) r meets the appropriate conversational presuppositions; or (7) an intellectually virtuous person would advance r as a reason for p." [6] Any of these conditions are sufficient to describe objectively available reasons and are compatible with infinitism. Klein concedes that, ultimately, the proper characterization of objectively available need be a member of this list, but, for the scope of Klein's defense of infinitism, he need not provide a fully developed account of objectively available reasons. Objective availability could be best understood, at least as a working definition, as an existing, truth-apt reason not dependant on the subject.

A subjectively available reason is stated as follows: "S must be able to call on r." (Subjectively available is comparatively straightforward compared to objectively available.) The subject must be able to evoke the reason in their own mind and use the reason in the process of justification. In essence, the reason must be "properly hooked up with S's own beliefs" in order to be subjectively available.

A reason that is both objectively and subjectively available to a subject is a candidate for justification according to infinitism (or, at least for Klein). [7]

Objection to Infinitism: Klein addresses an objection to infinitism.

The finite mind objection (attributed to John Williams): The human mind is finite and has a limited capacity. "It is impossible to consciously believe an infinite number of propositions (because to believe something takes some time) and it is impossible to "unconsciously believe" infinite number of propositions because the candidate beliefs are such that some of them "defeat human understanding." [8] It is simply an impossibility that a subject has an infinite chain of reasons which justify their beliefs because the human mind is finite. Klein concedes that the human mind is finite and cannot contain an infinite number of reasons, but the infinitist, according to Klein, is not committed to a subject actually possessing infinite reasons. "The infinitist is not claiming that in any finite period of time...we can consciously entertain an infinite number of thoughts. It is rather that there are an infinite number of propositions such that each one of them would be consciously thought were the appropriate circumstances to arise." [9] So, an infinite chain of reasons need not be present in the mind in order for a belief to be justified rather it must merely be possible to provide an infinite chain of reasons. There will always be another reason to justify the preceding reason if the subject felt compelled to make the inquiry and had subjective access to that reason.

See also

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The theory of justification is a part of epistemology that attempts to understand the justification of propositions and beliefs. Epistemologists are concerned with various epistemic features of belief, which include the ideas of justification, warrant, rationality, and probability. Loosely speaking, justification is the reason that someone (properly) holds a belief.

The regress argument is a problem in epistemology and, in general, a problem in any situation where a statement has to be justified.

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Belief is the state of mind in which a person thinks something to be the case regardless of empirical evidence to prove that something is the case with factual certainty. Another way of defining belief sees it as a mental representation of an attitude positively oriented towards the likelihood of something being true. In the context of Ancient Greek thought, two related concepts were identified with regards to the concept of belief: pistis and doxa. Simplified, we may say that pistis refers to "trust" and "confidence", while doxa refers to "opinion" and "acceptance". The English word "orthodoxy" derives from doxa. Jonathan Leicester suggests that belief has the purpose of guiding action rather than indicating truth.

In epistemology, a self-evident proposition is a proposition that is known to be true by understanding its meaning without proof, and/or by ordinary human reason.

The problem of induction is the philosophical question of whether inductive reasoning leads to knowledge understood in the classic philosophical sense, highlighting the apparent lack of justification for:

  1. Generalizing about the properties of a class of objects based on some number of observations of particular instances of that class or
  2. Presupposing that a sequence of events in the future will occur as it always has in the past. Hume called this the principle of uniformity of nature.
Friedrich Heinrich Jacobi German philosopher

Friedrich Heinrich Jacobi was an influential German philosopher, literary figure, and socialite.

Philosophical skepticism is a philosophical school of thought that questions the possibility of certainty in knowledge. Skeptic philosophers from different historical periods adopted different principles and arguments, but their ideology can be generalized as either (1) the denial of possibility of all knowledge or (2) the suspension of judgement due to the inadequacy of evidence.

In philosophy, a distinction is often made between two different kinds of knowledge: knowledge by acquaintance and knowledge by description. Knowledge by acquaintance is obtained through a direct causal (experience-based) interaction between a person and the object that that person is perceiving.

Evidentialism is a thesis in epistemology which states that one is justified to believe something if and only if that person has evidence which supports his or her belief. Evidentialism is therefore a thesis about which beliefs are justified and which are not.

Infinite regress

An infinite regress in a series of propositions arises if the truth of proposition P1 requires the support of proposition P2, the truth of proposition P2 requires the support of proposition P3, and so on, ad infinitum.

Broadly speaking, fallibilism is the philosophical claim that no belief can have justification which guarantees the truth of the belief. However, not all fallibilists believe that fallibilism extends to all domains of knowledge.

Münchhausen trilemma A thought experiment used to demonstrate the impossibility of proving any truth

In epistemology, the Münchhausen trilemma is a thought experiment used to demonstrate the impossibility of proving any truth, even in the fields of logic and mathematics. If it is asked how any knowledge is known to be true, proof may be provided. Yet that same question can be asked of the proof, and any subsequent proof. The Münchhausen trilemma is that there are only three options when providing proof in this situation:

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The following outline is provided as an overview of and topical guide to epistemology:

Epistemology or theory of knowledge is the branch of philosophy concerned with the nature and scope (limitations) of knowledge. It addresses the questions "What is knowledge?", "How is knowledge acquired?", "What do people know?", "How do we know what we know?", and "Why do we know what we know?". Much of the debate in this field has focused on analyzing the nature of knowledge and how it relates to similar notions such as truth, belief, and justification. It also deals with the means of production of knowledge, as well as skepticism about different knowledge claims.


  1. Ichikawa, Jonathan Jenkins; Steup, Matthias (2017-03-17). "The Analysis of Knowledge". In Zalta, Edward N. Stanford Encyclopedia of Philosophy (Fall 2017 ed.).
  2. Klein, Peter D.; Turri, John. "Infinitism in Epistemology". Internet Encyclopedia of Philosophy. Retrieved 2015-06-19.
  3. Klein, Peter D. (1999). "Human Knowledge and the Infinite Regress of Reasons". Philosophical Perspectives. 13: 297–325.
  4. Klein, Peter D. (1999). "Human Knowledge and the Infinite Regress of Reasons". Philosophical Perspectives. 13: 297–325.
  5. Klein, Peter D. (1999). "Human Knowledge and the Infinite Regress of Reasons". Philosophical Perspectives. 13: 297–325.
  6. Klein, Peter D. (1999). "Human Knowledge and the Infinite Regress of Reasons". Philosophical Perspectives. 13: 297–325.
  7. Klein, Peter D. (1999). "Human Knowledge and the Infinite Regress of Reasons". Philosophical Perspectives. 13: 297–325.
  8. Klein, Peter D. (1999). "Human Knowledge and the Infinite Regress of Reasons". Philosophical Perspectives. 13: 297–325.
  9. Klein, Peter D. (1999). "Human Knowledge and the Infinite Regress of Reasons". Philosophical Perspectives. 13: 297–325.