Lecture 13-Chapter 5 Notes
Common Types of Deductive Arguments
1. Argument based on Mathematics:
Ex. Mark has twice as many cats as Susan. Susan has 3 cats; therefore, Mark has 6 cats.
2. Argument from Deﬁnition:
Truth of conclusion is guaranteed by deﬁnition
Ex. Harold is Matilda’s son. Therefore, Matilda is Harold’s son.
Or: Jackson is a liar; therefore, he doesn’t tell the truth.
3. Sentential (Proposition Deductive Arguments:
MP, MT, HS, DS, CD, Conj, Simp, Add.
4. Categorical Syllogism:
Syllogism (two premised argument) with each statement starting with “all”, “some”, “none”, or
“every” (Ch. 5)
- In a categorical reasoning, the statements, or claims, of interests are categorical statements
- Categorical statement make simple assertions about categories, or classes, of things.
Ex. All cows are herbivores.
No gardeners are plumbers.
Some business people are cheaters.
Some business people are not moral.
- A categorical syllogism consists of three parts:
How to know which is major/minor. Any premise that has the predicate of the conclusion is the
major premise. “Greeks is the subject and it is repeated in the second premise, so it is the minor
Four Standard Forms (Pure Forms)
- Four standard forms of categorical statements:
1) All business people are cheaters.
2) No business people are cheaters
3) Some bu