Choose the right code : A deductive argument claims that : I. The conclusion…

Concept — A deductive argument is one whose conclusion is claimed to follow from its premises with logical necessity. That claim has two parts: the argument is non-ampliative, meaning the conclusion states nothing beyond what the premises already carry, and its support is conclusive rather than probabilistic, meaning it is impossible for all the premises to be true while the conclusion is false. An inductive argument makes the opposite kind of claim: it is ampliative, and its premises make the conclusion only probable.

Application — Test each of the four statements against that definition.

1. Statement I says the conclusion does not claim more than the premises contain. That is precisely the non-ampliative property, so it is part of what a deductive argument claims.

2. Statement II says the premises support the conclusion conclusively. That is the conclusive-support property, the second half of the deductive claim, and it is what separates deduction from the merely probable support given by induction.

3. Statement III says that if the conclusion is false, the premises may be either true or false. Take the contrapositive of conclusive support: if true premises force a true conclusion, then a false conclusion means the premises cannot all be true, so at least one of them must be false. The truth-value of the premises is therefore not left open, and leaving it open is what an inductive argument permits, not what a deductive argument claims.

4. Statement IV says that if the premises are true the conclusion must be true. That is truth-preservation, i.e. validity — and it is simply statement II’s conclusive support written as a conditional, because to say that the premises support the conclusion conclusively just is to say that true premises cannot yield a false conclusion. So statement IV is correct, but it names no property that statement II has not already named.

Cross-check — Read the four codes against that result.

Result — The list therefore contains exactly two distinct properties of the deductive claim, non-ampliative content and conclusive support, and statement III contradicts the second of them. The code “I and II” names both properties and carries no false statement, whereas every other code carries statement III. “All the above” is thus not needed in order to pick up statement IV, since statement IV is conclusive support restated and is already covered. Accordingly “I and II” is the correct code, and it is what the official UGC NET December 2012 Paper I answer key marks for this item.