Lei
from 400 BCE The Mohist dialectical chapters; the cosmological use is Han and later
Argument proceeds by kinds: establish that two things are of one kind and what holds of one holds of the other — and most bad argument is a confusion of kinds.
- Active
- from 400 BCE
- Where
- Warring States China
- Also
- lèi
- Status
- In use
- Tradition
- Non-Western procedures
What it is
Lei means kind or category, and in the Mohist dialectical chapters it is the central term of argument. To argue well is to extend a claim to things of the same kind and to refuse to extend it across kinds; to argue badly is to mistake one kind for another.
The Mohists give it a precise form. Their term tui lei, pushing out by kind, is the move of extending what is granted of one case to another of the same kind — and they are equally interested in the failures, cataloguing arguments that look parallel and are not.
How it works
Establish what kind the case belongs to, and on what basis — the Mohists require a reason, gu, for the classification. Identify what holds of that kind. Extend it to the case. Check for the standard failures: cases that resemble each other in wording but not in kind, and cases where a claim true of the kind is not true of every member.
The Mohist warning is that surface parallels between sentences are the commonest source of error, because two arguments can be identical in form and different in kind.
The form of the inference
- This case belongs to kind K, for a stated reason
- What holds of K holds of its members
- No relevant difference removes this case from K
- Therefore what holds of K holds of this case
- Check that the parallel is one of kind and not merely of wording
The argument
Proposition The two subsidy claims are not the same kind of claim, despite reading identically.
- Both applications say the same thing: that the business should receive the drought subsidy because its water costs rose above the trigger.
- The stated reason for the classification matters. The scheme's kind is businesses whose water costs rose because the drought reduced their allocation, and the reason for the classification is that the allocation is what the drought affects.
- The first claim is of that kind: the allocation was cut to twenty per cent and the shortfall was bought on the temporary market at eleven times the usual price.
- The second is not. That business is on town water at a fixed tariff, and its costs rose because the tariff was reindexed in July, which would have happened in a wet year.
- The two applications are parallel in wording and not in kind, and the parallel wording is exactly what the Mohists warn about — the sentences match, and the reasons behind the classification do not.
Therefore The first claim is within the scheme and the second is outside it, and nothing in the wording of either application would have shown that.
The Mohist requirement to state the reason for a classification is what made the difference. Without it, both applications assert membership of the same kind and there is no way to test either.
What it is good for
Eligibility decisions, scheme administration, and any argument where two cases are said to be relevantly alike. The requirement to give a reason for the classification is directly usable.
Where it fails
What fixes a kind is left open. The Mohists require a reason for classification and do not say what makes a reason good, so a determined arguer can construct a kind that includes what they want it to include — which is the same weakness that runs through analogy, qiyās and precedent.
The term also carries a second life that is much weaker. In Han cosmology lei becomes resonance between things of the same category across the five phases, licensing inferences between colours, organs, seasons and directions on the strength of shared classification alone. That is a different and far looser practice than the Mohist one, and the shared word has caused two thousand years of confusion about what Chinese reasoning by kind amounts to.
Common misconceptions
That Chinese thought lacks logic and reasons only by resonance. The Mohist dialectical chapters contain a developed theory of argument, definition and fallacy, and their disappearance from the mainstream tradition after the Han is a historical accident rather than evidence about Chinese reasoning.
Where it came from
The dialectical chapters of the Mozi, from the fourth and third centuries BCE, which are the most technically developed logical texts produced in classical China.
What became of it
The Mohist school vanished after the Han and its dialectical chapters were transmitted in a badly corrupted state, unread for most of two millennia and reconstructed only in the twentieth century.
Lasting influence
Enormous in what it might have been and small in what it was, since the texts were effectively lost. The looser cosmological sense of lei shaped Chinese medicine, divination and statecraft instead.
Why it still matters
Alive in scholarship on Chinese logic, and its central demand is usable anywhere.
Put another way
Two claims in the same words, on different footings.
Texts
The Mozi, dialectical chapters
Textually damaged and requiring a reconstructed edition. Graham's is the standard.
Where to start
A. C. Graham's Later Mohist Logic, Ethics and Science, which is both the reconstruction and the commentary.
The surprising bit
China produced a sophisticated logic in the third century BCE, the texts were garbled and abandoned, and the tradition acquired a reputation for having no logic largely because nobody could read the book that proved otherwise.
In their own words
Things may be of a kind and yet not alike in every respect
Who held it
A. C. Graham
Connections
- Relies on
- Argument by analogy
- Parallel to
- Qiyās
The verdict
A rigorous demand that classifications be justified, transmitted so badly that its own tradition lost it.