All philosophy questions
Open inquiry11 min4 historical perspectives

What can we claim to know?

Examine the differences among true belief, certainty, experience, and luck through three cases and four historical moments, then revisit the grounds for your first judgment.

Your judgments stay on this device and are not shared or transmitted.

This experience does not produce a score or philosophy profile.

Enter the historical conversation.

Different views show the same evidence-backed material. The map does not replace events whose location is unknown.

  1. 1Probably around 369 BCEPlato — A dialogue that leaves the definition open

    Plato · Theaetetus

    If knowledge is perception, true judgment, or true judgment with an account, why does the dialogue stop without settling on one?

    The Theaetetus successively tests candidates that identify knowledge with perception, true judgment, and true judgment with an account.

    Open primary and scholarly evidence

    The displayed account is an evidence-linked editorial paraphrase, not a direct quotation.

    • Theaetetus

      Plato · Perseus Digital Library text with Stephanus pagination

      Locator: Stephanus 151d–187a, 187b–201c, 201d–210a

      Open source
    • Plato on Knowledge in the Theaetetus

      Stanford Encyclopedia of Philosophy

      Locator: Sections 6–8

      Open source

    The dialogue ends in aporia without endorsing any of the three candidates as its final definition of knowledge.

    Open primary and scholarly evidence

    The displayed account is an evidence-linked editorial paraphrase, not a direct quotation.

    • Theaetetus

      Plato · Perseus Digital Library text with Stephanus pagination

      Locator: Stephanus 210a–b

      Open source
    • Plato on Knowledge in the Theaetetus

      Stanford Encyclopedia of Philosophy

      Locator: Introduction and section 9

      Open source

    The dialogue is commonly dated to around 369 BCE; no exact place of composition is asserted.

    Open primary and scholarly evidence

    The displayed account is an evidence-linked editorial paraphrase, not a direct quotation.

    • Plato on Knowledge in the Theaetetus

      Stanford Encyclopedia of Philosophy

      Locator: Introduction, date and dramatic frame

      Open source
    1. The Theaetetus is commonly dated to around 369 BCE.

      c. 369 BCE

  2. 21641Descartes — Using doubt as a method

    René Descartes · Meditations on First Philosophy

    Should every belief be withheld whenever error is possible, or is doubt a test used for a particular purpose?

    The First Meditation uses a method of withholding assent from prior opinions whenever there is any reason for doubt.

    Open primary and scholarly evidence

    The displayed account is an evidence-linked editorial paraphrase, not a direct quotation.

    • Meditationes de prima philosophia

      René Descartes · 1641 · Adam–Tannery VII, Corpus Descartes digital edition with page markers and original-edition images

      Locator: Meditation I, AT VII 17–18

      Open source
    • Descartes' Epistemology

      Stanford Encyclopedia of Philosophy

      Locator: Section 2.2

      Open source

    The Second Meditation argues that existence cannot be denied while the very act of being deceived or doubting is occurring.

    Open primary and scholarly evidence

    The displayed account is an evidence-linked editorial paraphrase, not a direct quotation.

    • Meditationes de prima philosophia

      René Descartes · 1641 · Adam–Tannery VII, Corpus Descartes digital edition with page markers and original-edition images

      Locator: Meditation II, AT VII 25

      Open source
    • Descartes' Epistemology

      Stanford Encyclopedia of Philosophy

      Locator: Section 4.1

      Open source

    Immediately afterward, the meditator limits the result by saying that what this existing self is has not yet been adequately understood.

    Open primary and scholarly evidence

    The displayed account is an evidence-linked editorial paraphrase, not a direct quotation.

    • Meditationes de prima philosophia

      René Descartes · 1641 · Adam–Tannery VII, Corpus Descartes digital edition with page markers and original-edition images

      Locator: Meditation II, AT VII 25–27

      Open source
    • Descartes' Epistemology

      Stanford Encyclopedia of Philosophy

      Locator: Section 4.1

      Open source

    The first Latin edition was published by Michael Soly in Paris in 1641.

    Open primary and scholarly evidence

    The displayed account is an evidence-linked editorial paraphrase, not a direct quotation.

    • Meditationes de prima philosophia

      René Descartes · 1641 · Paris: Michael Soly, first Latin edition

      Locator: Title page and imprint

      Open source
    1. The first Latin edition is published in Paris.

      1641 · Paris · 출판

  3. 31748Hume — Can experience carry us into the future?

    David Hume · An Enquiry concerning Human Understanding

    Can we speak of knowledge in ordinary life when our grounds fall short of complete proof?

    Hume divides the objects of human reason into relations of ideas and matters of fact.

    Open primary and scholarly evidence

    The displayed account is an evidence-linked editorial paraphrase, not a direct quotation.

    • An Enquiry concerning Human Understanding

      David Hume · 1748 · Hume Texts Online critical text with E/SBN paragraph numbering

      Locator: E 4.1–4.2

      Open source

    He argues that judgments about cause and effect are learned from experience rather than obtained by a priori reasoning alone.

    Open primary and scholarly evidence

    The displayed account is an evidence-linked editorial paraphrase, not a direct quotation.

    • An Enquiry concerning Human Understanding

      David Hume · 1748 · Hume Texts Online critical text with E/SBN paragraph numbering

      Locator: E 4.4–4.6

      Open source

    Hume argues that using experience to prove that past experience will continue into the future makes the reasoning circular.

    Open primary and scholarly evidence

    The displayed account is an evidence-linked editorial paraphrase, not a direct quotation.

    • An Enquiry concerning Human Understanding

      David Hume · 1748 · Hume Texts Online critical text with E/SBN paragraph numbering

      Locator: E 4.18–4.21

      Open source

    Hume explains the principle that leads us to expect the future after repeated experience as custom or habit.

    Open primary and scholarly evidence

    The displayed account is an evidence-linked editorial paraphrase, not a direct quotation.

    • An Enquiry concerning Human Understanding

      David Hume · 1748 · Hume Texts Online critical text with E/SBN paragraph numbering

      Locator: E 5.5–5.8

      Open source

    The final section presents mitigated scepticism as joining doubt, caution, and modesty to judgment while fitting inquiry to human capacities.

    Open primary and scholarly evidence

    The displayed account is an evidence-linked editorial paraphrase, not a direct quotation.

    • An Enquiry concerning Human Understanding

      David Hume · 1748 · Hume Texts Online critical text with E/SBN paragraph numbering

      Locator: E 12.24–12.26

      Open source

    The first edition was published by A. Millar in London in 1748 under the title Philosophical Essays Concerning Human Understanding.

    Open primary and scholarly evidence

    The displayed account is an evidence-linked editorial paraphrase, not a direct quotation.

    • Philosophical Essays Concerning Human Understanding — first-edition catalog record

      Folger Shakespeare Library · 1748 · London: A. Millar, 1748; ESTC T4022

      Locator: London: A. Millar, 1748; ESTC T4022

      Open source

    Jean-Bernard Mérian's French translation, Essais philosophiques sur l'entendement humain, was published by J. H. Schneider in Amsterdam in 1758.

    Open primary and scholarly evidence

    The displayed account is an evidence-linked editorial paraphrase, not a direct quotation.

    • Essais philosophiques sur l'entendement humain

      David Hume; translated by Jean-Bernard Mérian · 1758 · Amsterdam: J. H. Schneider, 1758

      Locator: Title page and volume metadata

      Open source
    • Essais philosophiques sur l'entendement humain — catalog record cb33991959k

      Bibliothèque nationale de France · 1758 · Amsterdam: J. H. Schneider, 1758; Jean-Bernard Mérian translator attribution

      Locator: Translator attribution and Amsterdam: J. H. Schneider, 1758 record

      Open source
    1. The first edition is published in London.

      1748 · London · 출판

    2. Jean-Bernard Mérian's French translation is published in Amsterdam.

      1758 · Amsterdam · 번역

  4. 41963Gettier — When truth and justification meet by luck

    Edmund Gettier · Is Justified True Belief Knowledge?

    If truth, belief, and reasonable justification are all present but their connection is accidental, is it knowledge?

    Gettier's paper appeared in June 1963 in Analysis, volume 23, issue 6, pages 121–123.

    Open primary and scholarly evidence

    The displayed account is an evidence-linked editorial paraphrase, not a direct quotation.

    • Is Justified True Belief Knowledge?

      Edmund L. Gettier · 1963 · Analysis 23(6), 121–123

      Locator: Article metadata, Analysis 23(6), 121–123

      Open source

    The paper argues that a case may satisfy truth, belief, and justification while still not intuitively amounting to knowledge.

    Open primary and scholarly evidence

    The displayed account is an evidence-linked editorial paraphrase, not a direct quotation.

    • Is Justified True Belief Knowledge?

      Edmund L. Gettier · 1963 · Analysis 23(6), 121–123

      Locator: Pages 121–123

      Open source
    • The Analysis of Knowledge

      Stanford Encyclopedia of Philosophy

      Locator: Section 3

      Open source

    In Case I, Smith's evidence points to Jones, but the hiring and the coins that make the proposition true happen by chance to concern Smith.

    Open primary and scholarly evidence

    The displayed account is an evidence-linked editorial paraphrase, not a direct quotation.

    • Is Justified True Belief Knowledge?

      Edmund L. Gettier · 1963 · Analysis 23(6), 121–123

      Locator: Case I, page 122

      Open source

    The short paper was followed by extensive debate in contemporary epistemology over supplementing justified true belief or finding a different analysis.

    Open primary and scholarly evidence

    The displayed account is an evidence-linked editorial paraphrase, not a direct quotation.

    • The Analysis of Knowledge

      Stanford Encyclopedia of Philosophy

      Locator: Sections 3–8

      Open source
    1. Gettier's short paper appears in Analysis.

      June 1963