QuestionsCan we be certain of anything?The idols of the mind
Can we be certain of anything?Through experience, with care

The idols of the mind

Francis Bacon 1561 · 1626Knowledge is power: observe and experiment.
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What it claims

To know nature, we must not trust the mind alone: we need a method that tests our ideas against the facts, looking first for what contradicts them. Forewarned in this way, we can guard against the idols.

Why

The mind distorts what it perceives and keeps only what proves it right; so we need an outside judge: the facts.

In short

"The idols of the mind" is an argument by Francis Bacon (Novum Organum, I, 38-49 (1620)) on the question "Can we be certain of anything?" (answer: through experience, with care). Its claim: To know nature, we must not trust the mind alone: we need a method that tests our ideas against the facts, looking first for what contradicts them. Forewarned in this way, we can guard against the idols. According to AskPhilosophy's logic check (Z3 solver), the argument is valid only if one grants a premise the author leaves unstated (P3). AskPhilosophy presents 2 objections, 0 of them with a documented reply, and the original text behind each premise, checked word for word.

Novum Organum, I, 38-49 (1620)
Valid with an implicit premise

Why do we get things wrong? For Bacon, our errors do not fall from the sky: they have precise sources, always the same, which he calls "idols" (from the Greek eidolon: a deceptive image). Those of the whole human species, those of each individual, those of words, those of learned systems. If we know them, we can guard against them. But not by thinking alone in our room: we must test our ideas against the facts, above all against the facts that contradict them. Four centuries before the psychology of cognitive biases, this already describes what is now called confirmation bias.

P1The human mind is beset by four kinds of "idols", constant sources of error: those of the species (the tribe), those of each individual (the cave), those of words (the market-place), those of received systems (the theatre).
P2These idols do not only deceive the senses: they distort the understanding itself, which mixes its own nature with that of things like a distorting mirror, and they reach even the principles accepted in the sciences. So the mind alone cannot be trusted.
P3 · implicit premiseIf the mind alone cannot be trusted, we need a judge outside the mind, and that judge is the facts of experience.
P4But faced with facts, the mind keeps those that prove it right and neglects the others; yet to establish a truth, the contrary instance is the more forcible. So we must look for contrary instances.
Therefore, to know nature, we must not trust the mind alone: we need a method that tests our ideas against the facts, looking first for what contradicts them. Forewarned in this way, we can guard against the idols.

click a premise to reject it

If you accept every premise, logic forces you to accept the conclusion. So the debate is about the premises.
Checked by a logic solver: the premises cannot all be true while the conclusion is false.
Without the implicit premise: Without P3, the computer finds a case where the mind alone is unreliable, but the remedy is not experience (for example revelation, or controlled mathematical reasoning): the conclusion no longer follows.
Valid with P3. Without it, Bacon would only have shown that the mind alone cannot be trusted: it would remain to say where to turn. P3 says the remedy is the facts. That is where he parts ways with the rationalists: Descartes answers that the mind can be trusted, provided we judge only what we conceive clearly. Note: Bacon does not say experience corrects everything. He knows the mind sorts facts to suit itself (P4): that is why a method is needed, not just observations.
Analogy. Bacon tells how a temple displayed the portraits of sailors who had made a vow to the gods and escaped shipwreck. "Do you now acknowledge the power of the gods?" A wise man answered: "But where are they painted that were drowned after their vows?" That is the whole argument: we count only the cases that prove us right.

Objections

2

Each objection is a conversation: click to see who replies and where the debate stands.

Descartes 1641 · attacks premise 2

The understanding does not err of itself: whatever I conceive, I conceive rightly. Error comes from the will, wider than the understanding, which judges what it does not understand. The remedy is not first of all experience, but discipline: judge only what one conceives clearly and distinctly.

no reply
No reply possible: objection raised in 1641, after the author's death (1626).
The debate goes on (our summary) The Meditations appeared in 1641, fifteen years after Bacon's death. The two diagnoses are close: Bacon too writes that the understanding "receives an infusion from the will and affections" (NO I, 49). They differ on the remedy: suspending judgement for Descartes, testing ideas against facts for Bacon.
Spinoza 1661 · attacks premise 1

Bacon "works out scarcely any proofs: he simply narrates". He asserts that the mind errs by its nature without demonstrating it. And all his causes of error come down to one, Descartes's: a free will wider than the understanding. Yet such a free will does not exist: each error has determinate causes, which we must know.

no reply
No reply possible: objection raised in 1661, after the author's death (1626).
The debate goes on (our summary) On the form, Spinoza is right: Bacon supports his idols with examples (the temple portraits, the omens remembered when they come true) rather than demonstrations. In the 20th century, experimental psychology measured several of these failings, such as confirmation bias. But it explains them, as Spinoza wanted, by definite causes in the workings of the mind, without appealing to a free will.