INVALIDARGUMENT

Invalidargument is a term that can refer to two related concepts in different domains: a logical concept describing a flaw in reasoning, and a programming concept referring to an error condition when a function receives an inappropriate argument.

In logic, an invalidargument describes an argument form that does not guarantee the truth of its conclusion even when all premises are true. The distinction between validity and truth is central: an argument is valid if, assuming its premises are true, the conclusion must be true. If that is not the case, the argument is invalid. Invalid arguments can have true premises or a false conclusion; the key point is that the conclusion does not logically follow from the premises. Common invalid forms include affirming the consequent (If P then Q; Q; therefore P) and denying the antecedent (If P then Q; not P; therefore not Q). These distinctions help separate the reliability of the reasoning form from the factual content of the premises.

In programming, InvalidArgument (or invalid_argument) is frequently used as the name of an exception or error condition raised when a function receives an argument that is outside the allowed range or otherwise inappropriate. Different languages implement this differently: C++ has std::invalid_argument, Java commonly uses IllegalArgumentException, and Python relies on ValueError or TypeError for similar situations. Proper handling involves input validation, clear error messages, and, when appropriate, early returns or exceptions to prevent further misuse.

See also validity, soundness, preconditions, and exception handling.