In logic, the argument form or test form of an argument results from replacing the different words, or sentences, that make up the argument with letters, along the lines of algebra; the letters represent logical variables. The sentence forms which classify argument forms of common important arguments are studied in logic.
To demonstrate the important notion of the form of an argument, substitute letters for similar items throughout the sentences in the original argument.
Original argument
All humans are mortal.
Socrates is human.
Therefore, Socrates is mortal.
Argument Form
All S are P.
a is S.
Therefore, a is P.
All we have done in the Argument form is to put 'S' for 'human' and 'humans', 'P' for 'mortal', and 'a' for 'Socrates'; what results, is the form of the original argument. Moreover, each individual sentence of the Argument form is the sentence form of its respective sentence in the original argument.[1]