QuestionsWhat is a just society?A law good here may be bad elsewhere
What is a just society?Virtue and harmony

A law good here may be bad elsewhere

Montesquieu 1689 · 1755To prevent abuse, power must check power.
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What it claims

The same law may be good for one people and bad for another: laws must be "adapted to the people for whom they are made".

Why

Peoples differ in climate and customs; a law against their customs makes them unhappy.

In short

"A law good here may be bad elsewhere" is an argument by Montesquieu (The Spirit of the Laws, I, 3 and XIX) on the question "What is a just society?" (answer: virtue and harmony). Its claim: The same law may be good for one people and bad for another: laws must be "adapted to the people for whom they are made". 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 3 objections, 2 of them with a documented reply, and the original text behind each premise, checked word for word.

The Spirit of the Laws, I, 3 and XIX
Valid with an implicit premise

Can we take the best laws of one country and impose them on another? Montesquieu answers that it would be "very unlikely" to work. Each people has a "general spirit", formed by its climate, religion, customs and manners. A law that clashes with this spirit makes the people unhappy. To change customs, example works better than force. Note: he does not say everything is equal. For him justice exists before all laws; what varies is how it is applied.

P1A law that follows a nation's spirit, without going against the principles of its government, is good for it: we do nothing so well as what we do freely.
P2Peoples differ in climate, soil, way of life, religion and customs: a law that fits one people's spirit may clash with another's.
P3Imposing on a people, by force, a law contrary to its customs makes it unhappy, and is tyrannical.
P4 · implicit premiseA law that makes a people unhappy and is imposed on it tyrannically is not a good law for it.
Therefore the same law may be good for one people and bad for another: laws must be "adapted to the people for whom they are made".

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 the law makes the second people unhappy, is imposed by force, and is still "good" for it: nothing yet links a people's unhappiness to the worth of a law.
With P4, the conclusion follows. P1 says why the law is good for the first people, P2 and P3 why it harms the second, P4 links that harm to the word "bad". P4 is implicit: Montesquieu judges laws by their effects on a people's happiness and liberty. That is where universalists attack: couldn't a just law displease and still be just? Note too that the argument concludes "may be", not "always is": Montesquieu does not say all laws are relative, since he posits a justice prior to all laws.
Analogy. A good doctor does not give every patient the same remedy: he takes age, body and habits into account. Health is the same for everyone, but the treatment changes. For Montesquieu, justice is like health, and laws are like remedies.

Objections

3

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

Condorcet 1819 · attacks the conclusion

A good law must be good for all men, as a true proposition is true for all. Justice, human rights, security and liberty are the same everywhere: why should laws change from one country to another? (Observations on Book XXIX of the Spirit of the Laws, written before his death in 1794, published in 1819.)

Montesquieu replies
summary: their text is not yet in our corpus
Montesquieu Montesquieu's anticipated reply (The Spirit of the Laws, I, 1 and I, 3)
There are relations of justice antecedent to positive law: to say there is nothing just or unjust but what the laws command is to say that before a circle was described all the radii were not equal. Law in general is human reason, inasmuch as it governs all the peoples of the earth; and the laws of each nation ought to be only the particular cases in which this human reason applies.
The debate goes on (our summary) Condorcet would answer: agreed on the principle, but then the part that varies should be small. Yet Montesquieu lets a great deal vary, sometimes the essential: he grants that slavery is "founded on natural reason" in some hot countries (XV, 7). The debate is about the boundary: what belongs to justice, valid everywhere, and what belongs to customs, which can be adapted?
Voltaire 1766 · attacks premise 2

Montesquieu knows these differences between peoples badly. The author of the Spirit of Laws "amuses himself in quoting the imaginary laws of Tonquin, Bantam, Borneo, and Formosa, upon the report of some travelers, or romancers, or persons misinformed". The basis of morality, the idea of just and unjust, is the same everywhere.

no reply
No reply possible: objection raised in 1766, after the author's death (1755).
The debate goes on (our summary) Montesquieu died in 1755. Voltaire is right about the sources: many exotic examples in The Spirit of the Laws come from dubious travel accounts. But on the substance the two are closer than he says: Voltaire himself writes, in the next chapter, that "there are a thousand differences in the interpretation of this law", even if "the basis ever remains the same". That is almost Montesquieu's thesis: one reason, different applications.
Hume, then the critics of climate theory 1748 · attacks premise 2

Climate does not make a people's character: neighbours under the same sky are very different, and a people changes without its climate changing. Moral causes (government, trade, imitation) are what count (Hume, "Of National Characters", 1748). Worse: climate theory was used to present despotism and slavery as natural for some peoples.

Montesquieu replies
summary: their text is not yet in our corpus
Montesquieu What Montesquieu writes in the same book (The Spirit of the Laws, XIV, 5 and XIX, 4)
Men are influenced by various causes: climate, religion, laws, the maxims of government, precedents, morals and customs. Bad legislators are those who favoured the vices of the climate, good ones those who opposed them: the more physical causes incline men to inaction, the more moral causes should draw them away from it.
The debate goes on (our summary) The reply is real, but it does not cover the whole book. Elsewhere Montesquieu writes that "the power in Asia ought to be always despotic" (XVII, 6), bases his theory on a physiology now known to be false ("fibres" tightened by cold, XIV, 2) and grants a "natural reason" for slavery in hot countries (XV, 7). These passages are read today as dated and ethnocentric theses. The idea that a law must take a people's customs into account does not need climate theory.