QuestionsCan science explain everything?The law of three states
Can science explain everything?It can explain everything

The law of three states

Auguste Comte 1798 · 1857Know only facts: the positive age of science.
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What it claims

There is no real knowledge except what rests on observed facts.

Why

Knowledge passes through three stages: the first two are provisional, and only the positive stage seeks laws through observation.

In short

"The law of three states" is an argument by Auguste Comte (Course of Positive Philosophy, 1st lesson (1830)) on the question "Can science explain everything?" (answer: it can explain everything). Its claim: There is no real knowledge except what rests on observed facts. According to AskPhilosophy's logic check (Z3 solver), the argument is valid only if one grants a premise the author leaves unstated (P4). AskPhilosophy presents 5 objections, 0 of them with a documented reply, and the original text behind each premise, checked word for word.

Course of Positive Philosophy, 1st lesson (1830)
Valid with an implicit premise

A child explains thunder by the anger of a god. Later, he speaks of a "force" of lightning. Later still, he measures electricity. Comte believes all humanity follows this path, and that each science travels it in turn: a theological age, a metaphysical age, a positive age. He draws a conclusion about knowledge: the positive age is the final age, and he counts as real knowledge only what rests on observed facts. But is this a law of history, or a way of deciding in advance that his opponents belong to the past?

P1Each branch of our knowledge passes through three successive states: theological, metaphysical, positive.
P2The first two states are provisional: theology was the only possible method at the start, metaphysics is only a passage to the third state.
P3The positive state gives up absolute notions and first causes. It seeks, through reasoning and observation, the actual laws of phenomena.
P4 · implicit premiseKnowledge is real only in the final state, not in a provisional state: what is only a stage or a method of transition does not count as real knowledge.
Therefore there is no real knowledge except what rests on observed facts.

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 P4, the computer finds a case where knowledge is real while in a provisional state (for example a true theological or metaphysical explanation), without resting on observed facts. It shows that the law of three states, by itself, says nothing about the truth of each state.
With P4, the argument is valid. P1 says all knowledge is in one of the three states. P2 says the first two are provisional. P4 says the provisional is not real knowledge: only the positive state is left. P3 says the positive state rests on observation. All the weight is on P4, which Comte does not prove: his law describes how ideas followed one another, not which one is true. If a theological or metaphysical explanation could be true without being the final state of history, the argument would fall. Comte answers partly in P2: those states served a purpose, but they set out to know the origin and first causes, which science, he says, cannot reach.
Analogy. A child goes from a tricycle to a bike with stabilisers, then to a bike. The stabilisers helped, but nobody says they were "the true way to ride". Comte says the same of gods and hidden forces. The critic answers: nothing proves the bike is the last stage, nor that the stabilisers carried no truth already.

Objections

5

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

Karl Popper, The Poverty of Historicism 1957 · attacks premise 1

Human history is a single process that does not repeat. One can spot trends in it, but a trend depends on conditions that can change: it is not a law. Announcing a necessary sequence in three stages is, for Popper, a case of historicism, a prophecy posing as science.

no reply
summary: their text is not yet in our corpus
No reply possible: objection raised in 1957, after the author's death (1857).
The debate goes on (our summary) Comte himself calls his discovery a "law" backed by "rational proofs" and "historical verifications" (1st lesson, §4), and he defers the full demonstration to the part of the course on social phenomena (§9): Popper's objection does target his project. His defenders answer that the law is checked science by science (astronomy, physics, chemistry, biology left the theological state at different times, §27) and that it describes a past evolution. Popper would reply that a succession said to be necessary remains a prophecy.
P
Peter Berger (ed.), The Desecularization of the World 1999 · attacks premise 1

Sociologists expected religion to fade as science advanced. Yet in most of the world (United States, Africa, India, the Muslim world), religion remains strong, and coexists with science and technology. The three states do not replace each other: they live together in the same societies, sometimes in the same head.

no reply
summary: their text is not yet in our corpus
No reply possible: objection raised in 1999, after the author's death (1857).
The debate goes on (our summary) Comte already grants that the branches of knowledge did not pass through the three states at the same speed and did not reach the positive state at the same time (1st lesson, §27). But this passage explains delays between the sciences, not the persistence of religion in highly scientific societies: it does not answer the objection. Comte expected the theological state to disappear in the end. Yet he himself ended by building a religion (see the argument on the Religion of Humanity), which shows he did not believe the religious need would vanish. His defenders would say the law concerns how natural phenomena are explained, not all religious life.
Averroes, The Decisive Treatise (c. 1179) 1179 · attacks premise 2

For Averroes, different minds reach the truth by different paths, at the same time, in the same society: some by demonstration, others by discussion, others by eloquence and images. Reason and religion do not follow one another like two ages of humanity: they speak to different natures. Comte's states would be types of mind, not stages.

no reply
We have not yet found a direct reply by Comte in the texts.
The debate goes on (our summary) Comte himself acknowledges that the natural sciences reached Western Europe through the Arabs (1st lesson, §28), but does not discuss this idea of parallel paths. A question remains: did medieval Arabic science grow against faith, as the law would have it, or alongside it?
John Stuart Mill, Auguste Comte and Positivism 1865 · attacks the conclusion

Mill admires the method of the Course, but refuses that "observed facts" should exclude inner facts. Comte had written that the mind can observe all phenomena except its own, for "who would make the observation?" (1st lesson, §52). Mill answers: we know our thoughts and feelings, if not while they happen, at least just afterwards, through memory. Forbidding psychology based on inner observation deprives science of a real source of facts.

no reply
summary: their text is not yet in our corpus
No reply possible: objection raised in 1865, after the author's death (1857).
The debate goes on (our summary) Mill wrote his book after Comte's death (1857). Comte does not consider the memory argument. He only grants that one can observe oneself as regards the passions, whose organs are distinct from those that observe, while judging such remarks of little scientific value (1st lesson, §52). He proposes other paths to the mind: the physiological study of our intellectual organs and the observation of the methods of science (1st lesson, §49). Mill's text is not yet in our corpus.
E
Edmund Husserl, The Crisis of European Sciences 1936 · attacks the conclusion

Reducing knowledge to observed facts leaves out questions of meaning: what reason, truth, freedom and human life are worth. A science of mere facts has nothing to say to those who ask why to live. For Husserl, positivism cuts philosophy off from its head.

no reply
summary: their text is not yet in our corpus
No reply possible: objection raised in 1936, after the author's death (1857).
The debate goes on (our summary) Comte already said that the positive spirit is as far from empiricism, the piling up of unconnected facts, as from mysticism (Discourse on the Positive Spirit, §15). He also tried to answer questions of meaning with sociology, then with the Religion of Humanity. Husserl would reply that these are still knowledge of facts about man, which do not say why science itself has meaning.