Notes on Introduction to Logic -- Phil A101

William Jamison - Instructor

Lecture on Syllogisms in Ordinary Language:

 The easiest way to test the validity of a syllogism is when it is in standard form but what if someone uses a syllogistic argument that is not in standard form?


Are the statements there but not in proper order?

(Notice that hypothetical syllogism looks like BARBARA if you reverse the major and minor premises. If p then q, and if q then r, therefore if p then r.)

Find the conclusion and put it last. The predicate of the conclusion gives you the major term. The major term must be in the major premise, and so you put the premise with the major term in it first. The minor premise is in the center.

Watch for synonyms.

We decorate our arguments by using different words for the same thing. Reducing terms by changing the synonyms to just one term gets rid of those.

Put the statments into standard form categorical propositons.

This often strikes us as odd since we do not speak in standard form categorical propositions. (This statement is an example. "This often strikes us as odd." would be what in standard form? Perhaps this: "All statements uttered in standard form are odd statements." But that is not really what I mean. Sometimes we do use standard form and it does not strike us as odd. So perhaps this: "Some statements uttered in standard form are odd statements." But even that misses a lot of what I mean. Translating the complexity of every day speech into standard form categorical propositions seems to lose a lot of meaning unless we delve into the very complex things we are saying.)


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