Meditations on Knowledge, Truth, and Ideas

Six pages that grade knowledge from obscure to adequate, and find Descartes' rule of clear and distinct ideas useless without a test.

by Gottfried Wilhelm Leibniz11 passages held

Latin, the original language

Original title: Meditationes de cognitione, veritate et ideis
First published: 1684(aged 38)
Original language: Latin

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Overview

Antoine Arnauld, the Jansenist theologian, and Nicolas Malebranche, the Oratorian philosopher, were quarrelling in print over what an idea is when Leibniz sent six pages on the subject to the Leipzig Acta Eruditorum, which printed them in November 1684 under his initials. Arnauld had opened the attack the year before with On True and False Ideas. Leibniz's first sentence mentions the controversy and adds that Descartes himself had not settled the matter. What he offers is a scale of knowledge. A notion is obscure when it cannot even pick out its object, as when we half remember a flower seen once and could not tell it from its neighbour; clear but confused when we recognise a colour without being able to say what marks it off; distinct when we can list those marks; adequate when the analysis goes all the way down. Its target was Descartes' rule that whatever we perceive clearly and distinctly is true. Without a test for distinctness, Leibniz said, the rule was useless: people were using it to certify their own imaginings. The same gap undid the proof of God from the idea of a most perfect being, an old scholastic argument that Descartes had revived: it works only once that being is shown to be possible, since a concept can hide a contradiction, as the idea of the fastest possible motion does. Of Malebranche's doctrine that we see all things in God, Leibniz said only that, even so, our minds must have ideas of their own. Twelve years later he was still pointing Johann Bernoulli, the Swiss mathematician, back to these pages in the Acta.

Key concepts

What makes a notion ‘obscure’, and what makes it ‘clear’?

A notion is obscure when it cannot even pick out its object: we half remember a flower seen once and could not tell it from its neighbour. It is clear when it does let us recognise the thing. So clarity is already more than obscurity, but it is not yet the ability to explain what one recognises.

What is the difference between confused, distinct and adequate knowledge?

Confused knowledge recognises a thing without being able to say what marks it off, as we know a colour on sight. Distinct knowledge can list those marks. Adequate knowledge carries the analysis all the way down, so that every mark used is itself distinctly known. Leibniz’s scale is a scale of how far analysis has gone.

What was wrong with Descartes’ rule of clear and distinct ideas?

It had no test. Descartes said that whatever we perceive clearly and distinctly is true, but without a way of checking whether a notion is really distinct, the rule certified whatever seemed evident to the person applying it. Leibniz said people were using it to certify their own imaginings, and so the rule was useless.

What gap did Leibniz find in the proof of God from perfection?

It assumes, without showing, that a most perfect being is possible. The old scholastic argument, revived by Descartes, reasons from the idea of such a being to its existence, but a concept can hide a contradiction, as the fastest possible motion does. The proof works only once the possibility of the being has been established.

Which quarrel were these six pages written into?

The dispute between Antoine Arnauld, the Jansenist theologian, and Nicolas Malebranche, the Oratorian philosopher, over what an idea is, opened by Arnauld’s On True and False Ideas in 1683. Leibniz’s first sentence mentions the controversy and adds that Descartes had not settled it. Of Malebranche’s view that we see all things in God, he said only that our minds must still have ideas of their own.

Themes of the book

What this book returns to, gathered into themes and ordered by how much of the text each one occupies.

From Obscure to Adequate: Grading What We Know

When can someone say they really know what they are talking about? Leibniz sorts notions on a scale, and the scale leaves Descartes’ rule of clear and distinct ideas without a test.

A notion is obscure when it cannot even pick out its object, like a flower seen once and half remembered; clear but confused when we recognise a colour without being able to say what marks it off; distinct when we can list those marks; adequate when the analysis goes all the way down. Descartes had said that whatever we perceive clearly and distinctly is true. Without a test for distinctness, Leibniz replied, the rule was useless: people used it to certify their own imaginings. Against Malebranche’s seeing all things in God, he said only that our minds must have ideas of their own.

epistemology
knowledge
ideas
concepts
cognition
definition
analysis
perception
sensory qualities
truth
methodology

Enter a dialogue

A Concept Can Hide a Contradiction

Does having an idea of something show that it could exist? Not yet, Leibniz argues, and the proof of God that Descartes had revived fails until that gap is closed.

The old scholastic argument, revived by Descartes, reasons from the idea of a most perfect being to its existence. Leibniz does not throw it out; he calls it incomplete. It works only once that being is shown to be possible, because a concept can hide a contradiction and still seem perfectly clear. His example is the fastest possible motion: the phrase sounds meaningful, yet no such motion can exist. Before reasoning from a notion to what follows from it, we owe some proof that the notion is possible at all.

possibility
ontological argument
contradiction
proof
demonstration
definition
logic

Enter a dialogue

Within this work

passages held: 11
distinct concepts: 24
by passages held, corpus-wide: #812

What this book thinks together

The wheel takes this book’s leading concepts and shows how often they come up together. The wider the band between two, the more of its passages speak of both. Among them, most often together: “epistemology” and “ideas”.

Concept co-occurrence, strongest first 2 concepts, joined by 1 pairing. 12 pairings reach beyond these concepts and are not drawn.
Concept	Paired concept	Shared passages
epistemology	ideas	4

Works held

The author's work in order, this book marked in place. Your-language title first, the original beneath it where the two differ; side chips show which full texts are held.

1684 Meditations on Knowledge, Truth, and Ideas (Meditationes de cognitione, veritate et ideis) you are here LA
1691 Whether the Essence of a Body Consists in Extension (Lettre sur la question si l'essence du corps consiste dans l'étendue)
Against the Cartesian view that body is nothing but extension: a letter to the Paris Journal des Sçavans in 1691, followed by a second in 1693.
FR
1695 New System of Nature (Système nouveau de la nature et de la communication des substances)
Leibniz's first public statement of his system, printed in Paris in 1695; his replies to Foucher and Bayle kept it in the journals until 1698.
FR
1698 On Nature Itself (De ipsa natura)
An answer to Johann Christoph Sturm in the Acta Eruditorum of 1698, defending forces inside created things and tying the dynamics to the metaphysics of substance.
LA
1710 Theodicy (Essais de Théodicée sur la bonté de Dieu, la liberté de l'homme et l'origine du mal)
Published anonymously at Amsterdam in 1710, it was the book by which the eighteenth century knew Leibniz, and the one Voltaire answered with Candide.
FR
1717 The Leibniz-Clarke Correspondence (Recueil des lettres entre Leibniz et Clarke)
Ten papers exchanged through the Princess of Wales in 1715–16, cut off by Leibniz's death and published by Clarke in 1717.
FR
1718 Principles of Nature and Grace, Based on Reason (Principes de la nature et de la grâce fondés en raison)
A companion summary from the same Vienna months as the Monadology, long mistaken for it and printed before it, in 1718.
FR
1720 Monadology (Monadologie)
Written in French in 1714, it was known for over a century only in German and Latin translation.
FR
1765 New Essays on Human Understanding (Nouveaux Essais sur l'entendement humain)
The book-length reply to Locke, written as a dialogue in 1703–04, withheld after Locke's death and first printed in 1765.
FR
1840 Discourse Touching the Method of Certitude and the Art of Discovery (Discours touchant la méthode de la certitude et l'art d'inventer)
A plea for royal patronage of the sciences, addressed to an unnamed king, apparently Louis XIV, setting out the method of certainty and art of discovery Leibniz pursued for decades.
FR
1840 On the Ultimate Origination of Things (De rerum originatione radicali)
A short Latin essay of 1697 on why there is a world at all, left in manuscript until 1840.
LA
1840 Reflections on the Doctrine of a Single Universal Spirit (Considérations sur la doctrine d'un Esprit Universel Unique)
A French essay written in 1702 at the Prussian queen's palace outside Berlin, and left unprinted until 1840.
FR
1846 Discourse on Metaphysics (Discours de métaphysique)
The opening statement of Leibniz's mature metaphysics, written early in 1686 and left unprinted until 1846.
FR
1846 The Leibniz-Arnauld Correspondence (Correspondance de Leibniz et d'Arnauld)
The exchange of 1686 to 1690 between Leibniz and Arnauld over the Discourse on Metaphysics, every letter carried by the Landgrave of Hessen-Rheinfels.
FR
1854 Refutation of Spinoza (Animadversiones ad Joh. Georg. Wachteri librum de recondita Hebraeorum philosophia)
Private Latin notes on Wachter's book about Spinoza and the Kabbalah, given their title by the French scholar who published them in 1854.
FR
1890 Tentamen Anagogicum: An Anagogical Essay in the Investigation of Causes (Essai anagogique dans la recherche des causes)
A French essay of about 1696, from the years of Leibniz's dynamics, defending final causes against the mechanical philosophers.
FR
1903 New Openings (Nouvelles Ouvertures)
Written in French in 1686, by the Academy edition's dating, and left in manuscript until Couturat printed it in 1903.
FR
1903 Preface to the General Science (Préface de la Science générale)
Probably from 1677, an unfinished preface to the universal language of reasoning, unprinted until 1903.
FR
1915 Confessio Philosophi (Confessio philosophi)
Leibniz's first developed theodicy, a Latin dialogue from his Paris years; revised after Steno's objections, its account of sin returns much changed in the Theodicy of 1710.
LA

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