Objection (argument)

This form of objection – invented by the presocratic philosopher Parmenides – is commonly referred to as a retroactive refutation.

In other words, it may be necessary to make an assumption in order to conclude anything from a set of true statements.

This assumption must also be true in order that the conclusion follow logically from the initial statements.

In the first example argument map, the objector can't find anything contentious in the stated premises of the argument, but still disagrees with the conclusion; the objection is therefore placed beside the main premise and, in this case, exactly corresponds to an unstated or 'hidden' co-premise.

This is demonstrated by the second example argument map in which the full pattern of reasoning relating to the contention is set out.