QuestionsWhat makes something right?The moral sense grew out of the social instincts
What makes something right?Nature or conscience

The moral sense grew out of the social instincts

The evolutionary origin of conscience; Darwin's moral sense

Charles Darwin 1809 · 1882Living things are explained by natural selection, without a prior plan.
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What it claims

Any animal endowed with well-marked social instincts would acquire a moral sense as soon as its intellectual powers became as developed as man's: conscience is a product of evolution.

Why

A highly social animal, once its intelligence is developed enough, regrets having yielded to a passing urge against its lasting instinct.

In short

"The moral sense grew out of the social instincts" is an argument by Charles Darwin (Darwin, The Descent of Man, 1871, ch. III (ch. IV in the 2nd ed., 1874)) on the question "What makes something right?" (answer: nature or conscience). Its claim: Any animal endowed with well-marked social instincts would acquire a moral sense as soon as its intellectual powers became as developed as man's: conscience is a product of evolution. 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 4 objections, 2 of them with a documented reply, and the original text behind each premise, checked word for word.

Darwin, The Descent of Man, 1871, ch. III (ch. IV in the 2nd ed., 1874)
Valid with an implicit premise

Where does that little voice come from that says "you should have"? For Darwin, it did not fall from the sky, and it is no miracle reserved for humans: it is the natural product of two things we share with other animals. The first is the social instinct: the pleasure of being with others, sympathy, doing services. The second is an intelligence developed enough to remember what one has done. When a lasting social instinct has given way to a stronger but passing urge, memory produces regret. With language, the opinion of the community weighs on us, and habit strengthens all this. Darwin does not say that an animal's morality would be ours: it might be very different. He says that conscience is a product of evolution.

P1Social instincts lead an animal to enjoy the company of its fellows, to feel sympathy for them and to perform services for them. They were strengthened by natural selection, since the communities with the most sympathetic members flourish best.
P2Once its mental faculties are highly developed, the animal constantly revisits its past actions. When the lasting, ever-present social instinct has yielded to another instinct, stronger at the moment but leaving no vivid impression, it feels dissatisfaction or misery.
P3With language, the common opinion on how to act for the public good becomes the main guide to action, and habit strengthens the social instinct, sympathy and obedience to the community.
P4 · implicit premiseAn animal that feels sympathy for its fellows and regret when it has failed them has what we call a moral sense or conscience: the feeling that it ought to have acted otherwise.
Therefore any animal endowed with well-marked social instincts would acquire a moral sense as soon as its intellectual powers became as developed as man's: conscience is a product of evolution.

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 an animal feels sympathy and regret without having a moral conscience in the sense of a recognised "duty": mere unease, with no notion of right or wrong.
The argument is valid with the hidden premise P4. P1 and P2 give sympathy and regret in any social and intelligent animal; P4 says that sympathy and regret are the moral sense. Objections target P4: they say that explaining where a feeling comes from does not say what its verdict is worth, and that this feeling varies with species or society.
Analogy. A child is hungry and eats the cake they were asked to share. The pleasure fades fast, but the memory of the disappointed sibling remains. Darwin thinks this scene is the familiar form of a mechanism much older than humanity.

Objections

4

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

John Stuart Mill (moral feelings are acquired) 1863 · attacks premise 1

Mill believes the moral feelings are not innate but acquired, yet not less natural for that: it is natural to man to speak, to reason, to build cities, though these are acquired faculties. So no inheritance of moral instincts is needed.

a defender replies
Charles Darwin defender of the argument · 1871
Darwin replies that, on the general theory of evolution, the idea that the moral sense is acquired by each individual during his lifetime is at least extremely improbable, and that ignoring transmitted mental qualities is a serious blemish in Mill's works.
Where the debate stands (our summary)Our summary: the debate is about the share of heredity and of upbringing. Darwin defends an inherited basis; Mill, an acquired but natural origin. Both accept that morality has a natural history. The debate is still open.
Henry Sidgwick (the superior bee) 1872 · attacks premise 4

Darwin says humans reared like hive-bees would think it a sacred duty to kill their brothers. Sidgwick replies that a superior bee would surely aspire to a milder solution of the population question. So the moral sense is not just a social instinct: it judges what is done with that instinct.

a defender replies
Charles Darwin defender of the argument · 1874
Darwin quotes Sidgwick's remark himself, then replies that, judging from the habits of most savages, man solves the problem by female infanticide, polyandry and promiscuous intercourse: it may therefore be doubted that he would do so by a milder method.
Where the debate stands (our summary)Our summary: Darwin's reply is a supposed fact about human societies, not a proof, and its vocabulary ("savages") is that of his time. Sidgwick's question remains: can the moral sense judge the instinct it comes from?
David Hume (from "is" to "ought") 1739 · attacks the conclusion

Hume notes that authors move suddenly, without saying so, from propositions about what is to propositions about what ought to be, though an "ought" is a new relation that needs explaining. Applied to Darwin (our reconstruction: Hume too grounds morality in feeling): describing the origin of the feeling of duty does not say that this feeling is right.

no reply
We have not yet found a direct reply by Darwin in the texts.
The debate goes on (our summary) Our summary: Darwin did not answer; the objection predates him but he does not treat it. He explains the "ought" as the memory of a lasting instinct sacrificed to a passing one ("the one course ought to have been followed, and the other ought not"), which describes the feeling without establishing its correctness.
Where the debate stands (our summary)Our summary: Darwin's argument is a thesis about the origin of conscience, not about moral truth. Defenders say that is all he claims; critics say the thesis is then silent on what matters.
Thomas Huxley (the ethical process against the cosmic process) 1893 · attacks the conclusion

For Huxley, social progress means checking the cosmic process, the struggle for existence, at every step and substituting an ethical process for it. The ethical progress of society depends not on imitating the cosmic process but on combating it.

no reply
No reply possible: objection raised in 1893, after the author's death (1882).
The debate goes on (our summary) Our summary: Huxley writes eleven years after Darwin's death. Darwin does not hold that morality imitates the struggle: he derives conscience from sympathy, which is not competition. But Huxley questions whether evolution alone explains values.
Where the debate stands (our summary)Our summary: Huxley and Darwin agree that sympathy matters; they differ on the place of evolution in morality. The debate is open.