Insofar as we are concerned with asking if the reasons given really do support the view in question, we are concerned with a logical inquiry. Inference is the name given to the reasoning process by which we are led to assert or deny the truth of a conclusion on the basis of other beliefs assumed to be true. However, corresponding to every inference, insofar as the beliefs in question can be expressed in language, one can formulate a group of statements as an argument leading to the conclusion in question. An argument is not merely any group of statements. It must exhibit a flow of thought from the reasons given in the premises to the truth of the conclusion.
Some arguments are better than others, and some, of course, are altogether bad.
Rhetoric must inevitably involve considerations of psychological and social matters, for different persons and different cultures will differ in what they consider persuasive. Logic has no concern with such questions that lead to the formation of belief, but is concerned only with the argument itself, not with those who use it or may or may not find it persuasive. Obviously logic may be used as a device for persuasion, but it is easy to imagine situations in which purely logical considerations carry little persuasive force. Since two or more sentences in a language, as well as different sentences in different languages, can have the same meaning, the same statement can be expressed by different sentences. The second defining characteristic further restricts the class delimited by the first characteristic.