In logic, an argument requires a set of (at least) two declarative sentences (or "propositions") known as the premises or premisses along with another declarative sentence (or "proposition") known as the conclusion. This structure of two premises and one conclusion forms the basic argumentative structure. More complex arguments can use a sequence of rules to connect several premises to one conclusion, or to derive a number of conclusions from the original premises which then act as premises for additional conclusions. An example of this is the use of the rules of inference found within symbolic logic.
- Socrates is mortal because all men are mortal.
It is evident that a tacitly understood claim is that Socrates is a man. The fully expressed reasoning is thus:
- Because all men are mortal and Socrates is a man, Socrates is mortal.
In this example, the independent clauses preceding the comma (namely, "all men are mortal" and "Socrates is a man") are the premises, while "Socrates is mortal" is the conclusion.
The proof of a conclusion depends on both the truth of the premises and the validity of the argument. Also, additional information is required over and above the meaning of the premise to determine if the full meaning of the conclusion coincides with what is.
For Euclid, premises constitute two of the three propositions in a syllogism, with the other being the conclusion. These categorical propositions contain three terms: subject and predicate of the conclusion, and the middle term. The subject of the conclusion is called the minor term while the predicate is the major term. The premise that contains the middle term and major term is called the major premise while the premise that contains the middle term and minor term is called the minor premise.
A premise can also be an indicator word if statements have been combined into a logical argument and such word functions to mark the role of one or more of the statements. It indicates that the statement it is attached to is a premise.
- In logic, premise and premiss are regarded as variant spellings of the same word, premise being the more common spelling. Charles Sanders Peirce (1839–1914) argued that premise and premiss are two distinct words, writing "As to the word premiss,—in Latin of the thirteenth Century praemissa,—owing to its being so often used in the plural, it has become widely confounded with a totally different word of legal provenance, the 'premises,' that is, the items of an inventory, etc., and hence buildings enumerated in a deed or lease. It is entirely contrary to good English usage to spell premiss, 'premise,' and this spelling...simply betrays ignorance of the history of logic."
- Room, Adrian, ed. (2000). Dictionary of Confusable Words. New York, NY: Routledge. p. 177. ISBN 1-57958-271-0. Retrieved 22 May 2014.
- Peirce Edition Project, ed. (1998). The Essential Peirce: Selected Philosophical Writings. 2. Bloomington, IN: Indiana University Press. p. 294. ISBN 0-253-21190-5. Retrieved 22 May 2013.
- Audi, Robert, ed. (1999). The Cambridge Dictionary of Philosophy (2nd ed.). Cambridge: Cambridge University Press. p. 43. ISBN 0-521-63136-X.
Argument: a sequence of statements such that some of them (the premises) purport to give reasons to accept another of them, the conclusion
- Gullberg, Jan (1997). Mathematics : From the Birth of Numbers. New York: W. W. Norton & Company. p. 216. ISBN 0-393-04002-X.
- Byrne, Patrick Hugh (1997). Analysis and Science in Aristotle. New York: State University of New York Press. p. 43. ISBN 0791433218.
- Ryan, John (2018). Studies in Philosophy and the History of Philosophy, Volume 1. Washington, D.C.: CUA Press. p. 178. ISBN 9780813231129.
- Potts, Robert (1864). Euclid's Elements of Geometry, Book 1. London: Longman, Green, Longman, Roberts, & Green. p. 50.
- Luckhardt, C. Grant; Bechtel, William (1994). How to Do Things with Logic. Hillsdale, NJ: Lawrence Erlbaum Associates, Publishers. p. 13. ISBN 0805800751.