The Building Blocks of Logic

SYLLOGISMS

IT’S A LITTLE BIT LIKE MATH…

 IF A=B  And C=A  Then B=C All humans have brains. Mrs. Miedwig is a human.

Mrs. Miedwig has a brain.

SOUND, VALID, OR INVALID?

 Sound= The premises are both unequivocally true  Valid= At least one of the premises is up for debate  Invalid= The two premises do not have to lead to that conclusion

RELATIONSHIP TO TOULMIN

Warrant: All humans have a heart.

Data/ Support: Mrs. Miedwig is human.

Claim: Mrs. Miedwig has a heart.

Let’s talk about ORDER: Warrant: Good schools contain strong fine arts programs.

Data/ Support: Crystal Lake South has a strong fine arts program.

Claim: Crystal Lake South is a good school.

ENTHYMEME

 A syllogism as stated in writing, typically with one premise missing. This usually means there’s more to say to defend your ideas.

 Examples:  Assisted suicide is wrong because killing is wrong.

 If killing babies is wrong, then abortion is obviously wrong.  Capital punishment is wrong because it is killing someone.

ANOTHER EXAMPLE

 Full syllogism –  All humans are mortal. (This one is left out of the enthymeme)  Michael is human.  Therefore, Michael is mortal.

 Enthymeme – Michael is mortal because he’s human.

EXAMPLE IN MLK

 “Since I feel that you are men of genuine good will and that your criticisms are sincerely set forth, I want to try to answer your statement in what I hope will be patient and reasonable terms.” Syllogism: Sincere criticism from good people should be answered.

You are good people with sincere criticism.

Your criticism should be answered.

ANOTHER EXAMPLE

 “The purpose of our direct-action program is to create a situation so crisis-packed that it will inevitably open the door to negotiation.” Syllogism: Situations that are crisis packed open the door to negotiation.

The situation we are creating is crisis packed.

Our situation will open the door to negotiation

PRACTICAL APPLICATION

 Look for assumptions in your own writing and be sure to defend them. (Warrants!)  Look for assumptions in other people’s writing and attack them. (Debates!)  Watch out for invalid syllogisms/ invalid logic.  Example: Men are stronger than women, so women cannot serve in the military.

“THE CASE FOR TORTURE”

 Find examples where Levin uses syllogisms within his argument and write them out.

 Write a syllogism for Levin’s OVERALL argument.

 Is Levin’s argument sound? valid? invalid? Explain your answer.