In Logic the term 'argument' is defined as a set of at least two statements (or propositions) where one is logically dependent upon the other.

The logical connection between the two statements is called an inference. The direction of the inference determines the dependency relationship between the two parts of the argument:

The structure of an argument is determined by the type of reasoning that governs the inference between premises and conclusions.

Deductive (or Formal) arguments are strictly ordered so as to insure the conclusion follows necessarily from the premise(s). That is, if the statements are put together in the proper form, the concluding statement will follow with logical necessity (it cannot not follow).

Inductive (or Informal) arguments can be loosely organized because, unlike a deductive argument, the conclusion of an inductive argument only follows the premise(s) with a degree of probability. The degree of probability with which the conclusion follows is determined by the amount, type, and relevance of the evidence (articulated in the premise(s)).

When an argument fails the rules of reason, it is said to have committed a fallacy.

There are two distinct families of logical fallacies:

The function or purpose of an argument is to persuade others using reason alone, or to demonstrate the rational process by which one has arrived at some belief.

Arguments are the tools by which philosophers investigate their various fields of inquiry.