Deductive argument involves

Concept: A deductive argument claims that its conclusion follows necessarily from its premises: if the premises are true, the conclusion cannot be false. What does the work in such an argument is the logical relation holding between the propositions — the form of the inference itself, which either holds or does not. It stands in contrast to an inductive argument, which moves from particular instances to a general claim and whose conclusion is only probable, growing stronger as more supporting cases accumulate.

Application: The stem asks what a deductive argument essentially consists in — the feature that makes it deductive, rather than a habit of mind that a reasoner may bring to arguments of any kind. Trace one standard example step by step:

1. Take the premises 'All human beings are mortal' and 'Socrates is a human being'.

2. The second premise places Socrates inside the class named by the first, so the predicate 'mortal' attaches to him through the relation between the two statements alone.

3. Draw the conclusion 'Socrates is mortal'. Affirming both premises while denying this conclusion would be self-contradictory, so the conclusion is necessary rather than merely likely.

4. Note what was never used: no count of how many mortal human beings have been examined, and no appeal to accumulated data. The inference rests entirely on seeing the logical relation between the propositions.

Cross-check: Test the remaining descriptions against that account of deduction:

• Sufficient evidence is the standard by which an inductive conclusion is judged — how much support has been gathered — whereas the necessity of a deductive conclusion does not increase when more evidence is added.

• Repeated observation is the engine of enumerative induction, generalising from many observed instances; a valid deduction requires no instances at all.

• Critical thinking is a broad intellectual disposition that a reasoner may bring to arguments of every kind, deductive and inductive alike; because it is peculiar to no single form of inference, it does not name what a deductive argument consists in.

A deductive argument therefore involves seeing logical relations among the propositions that make it up.