Under what condition does a deductive argument count as valid?

In logic, a deductive argument is considered valid if the truth of its premises logically guarantees the truth of its conclusion.12

This means that the argument's structure is such that it is impossible for the premises to be true while the conclusion is false. Validity depends entirely on the form or structure of the argument rather than the actual truth or falsity of the statements in the "real world". If an argument is valid, it would be inconsistent or self-contradictory to assert the premises while denying the conclusion.345

It is important to distinguish validity from soundness: an argument is sound only if it is valid and its premises are actually true. A logician is primarily concerned with the validity of the inference form, whereas the truth of the premises is a matter of factual observation. Arguments that fail to meet these criteria for logical necessity may be classified as fallacies if they provide no rational grounds for accepting the conclusion.412