Syllogisms Flashcards
What is the difference between deductive and inductive reasoning?
In each deductive reasoning the premises either do or do not contain conclusive arguments for the truth of the conclusion. If deductive reasoning is valid, it can in no way be invalid, and vice versa. If it is valid, the reasoning is conclusive and its conclusion is inevitable rather only having a degree of probability. The conclusion is not just plausible but imperative.
What does ‘M’ mean?
Middle term
What does ‘S’ mean?
Subject of the conclusion; also called the minor term because of the premise in which it occurs: the second premise
What does ‘P’ mean?
predicate of the conclusion; also called the major term, and this term is adopted for the first premise.
What does the standard format of the syllogism diagrams look like?
The first premise is always the one which contains the predicate of the conclusion (P); the second premise is the one which contains the subject of the conclusion (S).
Principle of non-contradiction
Something cannot be (a certain way) and at the same time not be (a certain way).
What is important about the middle term?
There is only such a connecting concept (the middle term) if it means exactly the same in the one context as in the other.
-> The syllogism is valid only if the middle term has its own identity and is related in the same capacity to each of the two other terms.
How can syllogisms be invalid?
a) The incorrect use of negation: Poor people are not happy. Rich people are not poor. Therefore, rich people are happy.
b) A shift in the field of reality to which a term refers: Some Turks are Europeans. Some Turks are Asians. Therefore, some Asians are Europeans.
c) An ambiguity in a term: What thou has not lost, thou hast. Thou has not lost thy horns. Ergo, thou hast horns.
First rule
There must be three terms.
Second rule
No term must have greater extension in the conclusion than it does in the premises.
Third rule
The conclusion must not contain the middle term.
Fourth rule
The middle term must be universal at least once.
Fifth term
Two positive premises cannot yield a negative conclusion.
Sixth Rule
Two negative premises yield nothing.
Seventh rule
The conclusion is negative if one of the premise is negative and is particular if one of the premises is particular.
