Contrary and Contradictory Terms

"Valid" and "void" are contraries because "voidable" sits between them.

"Legal" and "illegal" are contraries in most contexts, because a great deal of conduct is neither commanded nor forbidden, which is why the law recognises acts that are merely permitted.

Why it matters in argument

Treating contraries as contradictories is a standard error and it produces a standard bad argument: disprove one and claim the other.

"The prosecution has not proved that the accused was at the scene, therefore he was elsewhere." No. "At the scene" and "elsewhere" would be contradictories if the universe were fixed, but the argument does not reach that far: failure to prove presence establishes only that presence is not proved, which under section 2(1)(i) is the middle state and not the opposite one.

"The agreement is not valid, therefore it is void." No. It may be voidable, in which case it is valid until avoided.

"The witness has not been shown to be truthful, therefore he is lying." No. He may be mistaken, which is neither.

The rule in one line: from the falsity of one contrary, nothing follows about the other. From the falsity of one contradictory, the truth of the other follows at once. That single asymmetry is what the whole distinction is for.

A worked example

An Act provides that a licence shall be granted to any applicant who is a "fit person", and that no licence shall be granted to a person who is "unfit".

Are "fit" and "unfit" contradictories or contraries here? If they are contradictories, every applicant is one or the other and the Act is complete. If they are contraries, there is a middle class of applicants who are neither fit nor unfit, and the Act says nothing about them.

The answer turns on the wording and it is not a matter of taste. "Unfit" formed by simple negation of "fit" would give contradictories. But the Act uses "unfit" as a positive characterisation, a finding to be made against a person, and a finding of unfitness would need material. An applicant about whom nothing is known is not thereby unfit; he is simply not shown to be fit.

The practical consequence. On the contrary reading, an authority that refuses a licence must find the applicant unfit and cannot rest on the absence of proof of fitness, unless the Act places the burden on the applicant. On the contradictory reading it may. The whole administrative law of the provision follows from a distinction taught in a first-year logic paper, which is why the topic is on a law syllabus at all.

Distinctions that carry marks

What this does not mean

Contrary is not the same as merely different. "Red" and "chair" are different and are not contraries. Contraries are extremes within one class, so they must be comparable to begin with.

A negative prefix does not settle it. "Unfit" may be used as a simple negation or as a positive finding, and the Act's own scheme decides which. This is the point of the worked example.

"Contradictory" here is not the law of contradiction. The law says a proposition cannot be both true and false; contradictory terms are a relation between two terms. They are connected but they are not the same thing.

Quick revision

Contradictory terms: one is the simple negative of the other; nothing falls outside the pair and nothing falls in both.

Contrary terms: extremes of one scale; both can be false, and the middle ground often has its own name.

The test: can both be false? Yes means contrary; no means contradictory.

Legal examples: registered and unregistered are contradictory; valid and void are contrary, with voidable between; proved and disproved are contrary, and section 2(1)(i) BSA 2023 names the middle as "not proved".

Guilty and innocent are contraries made to behave as contradictories by the presumption of innocence, which is a legal rule and not a logical one.

The standard bad argument: disproving one contrary and claiming the other.

Terms here, propositions at sequence 410. Same words, different subject.

Test yourself

1. Distinguish contradictory from contrary terms and state the test.

Two terms are contradictory when one is the simple negation of the other, so that within the universe of discourse everything falls under exactly one of them. They are contrary when they are the extremes of a single scale, so that a thing may fall under neither. The test is whether both can be false of the same thing at once: if they can, the terms are contrary; if they cannot, they are contradictory. Both can never be true, whichever relation holds.

2. Give two legal examples of contrary terms and identify the middle ground in each.

"Valid" and "void" are contrary, the middle ground being "voidable", an agreement which is valid until it is avoided. "Proved" and "disproved" are contrary, and here the statute names the middle itself: section 2(1)(i) of the Bharatiya Sakshya Adhiniyam 2023 provides that a fact is not proved when it is neither proved nor disproved.

3. Are "guilty" and "innocent" contradictory terms?

Not as a matter of logic. Logically there is a middle state, namely that guilt has not been established and innocence has not been established either. What makes the pair behave as contradictories in a criminal trial is the presumption of innocence, a legal rule directing that a person not proved guilty be treated as innocent. The gap is closed by decision rather than by necessity, and that is worth saying in an answer.

4. What follows from the falsity of one of a pair of contraries?

Nothing about the other. If it is false that the agreement is void, it does not follow that it is valid, because it may be voidable. This is the asymmetry that makes the distinction worth learning: from the falsity of one contradictory the truth of the other follows immediately, while from the falsity of one contrary nothing whatever follows.

5. Identify the fault: "The prosecution has failed to prove that the accused was at the scene, so he was elsewhere."

The argument treats a pair of contraries as if they were contradictories. Failure to prove presence establishes only that presence is not proved, which under section 2(1)(i) of the Bharatiya Sakshya Adhiniyam 2023 is the middle state of "not proved", and it says nothing about where the accused actually was. The conclusion asserted requires affirmative material of its own.

6. Why must this distinction be kept separate from the one at topic 3.2?

Because topic 3.2 concerns contradictory and contrary propositions, not terms. "All A are B" and "No A is B" are contrary propositions and both can be false; "All A are B" and "Some A are not B" are contradictory propositions and exactly one is true. The test is the same question, whether both can be false, but the things related are different, and answers that mix them up describe the square of opposition when asked about terms.