Syllogisms

Syllogisms  are a type of statement where a conclusion is drawn from two reasons (premises), each of which shares a term with the conclusion. (e.g., all dogs are animals; all animals have four legs; therefore all dogs have four legs ). If the reasons are true, the conclusion must be true. There are a variety of types. In Debating the terms and names are not necessary but they can be an effective way to create arguments. 

Types of Syllogisms

- Standard or Categorical Syllogisms

(P is true for R) +(Q is type of R) = (P is true for Q)

Example 1: All good hockey players are physically fit + Tom is a good hockey player = Tom is physically fit.

Example 2: Anything that causes students to learn more is good  + smaller classes cause students to learn more = smaller classes are good

- Hypothetical Syllogisms

(if P, then Q) + (if Q, then R) = (if P, then R)

Example 1: If I tell the truth, I will be unpopular + if I am unpopular, I will lose the election =if I tell the truth, I will lose the election

Example 2: If she gets elected, nothing will be done about global warming + if nothing is done about global warming, millions will die = if she gets elected, millions will die.

- Great for argument in parts, which can allow you to lead the audience to connect two things which they would not normally connect

- Disjunctive Syllogisms

(Either R or S) + not R = S

Example 1: Either we cut back on medical spending or we raise taxes + we won't cut back on medical spending = we must raise taxes

Example 2: Either I work harder or I fail + I won't accept failing = I must work harder

- Argument by alternative

Types of Conditions

- Sufficient conditions

- if B is a sufficient condition for C, then if you have B then C must be true but the presence of C doesn't mean that you must have B

- For example, having a billion dollars in gold (B) is a sufficient condition for being rich (C), but just because you are rich (C) does not mean that you have a billion dollars in gold (B)

- can be useful if it is easier to prove the presence of B than C

- e.g. proving that a government is right wing because it is primarily concerned with supporting business and the military if being primaily concerned with supporting business and the military is a sufficeient condition for being right wing

- e.g. using any general principle to prove a specific case

- e.g. censorship, sexual assault

- e.g. proving that change is needed because the system is not working

- Necessary conditions

- if B is a necessary condition for C, then if you have C you have B but the presence of B doesn't mean that you must have C

- For example, being human(B) is a necessary condition for being a citizen of Canada (C), so any Canadian citizen is human, but it is possible to be a human (B) and not be a Canadian citizen (C) so being human is not a sufficient condition for being a Canadian citizen.

- can be useful if it is easier to prove the existence of C

- e.g. demonstrating that oxygen is present in a room becasue the presence of oxygen is a necessary condition for human life so if humans are living in the room, there must be oxygen

- disproving a general principle from a specific example e.g. if having roughly equal numbers of men and women in a profession is a necessary condition for a non-sexist society, then if you are a non-sexist society you will have roughly equaly numbers of men and women in a job, and if you don't you are not a non-sexist society.

3. Modi ( Useful for argument by acceptance and for cross examination)

- can alter what you have to prove

- in cross-ex, get them to admit one part or both parts at different times, then put them together

- often these involve hidden premises in your opponents arguments

- Modus ponens

P + (if P, then Q) = Q

Example 1: We want to make certain that our soldiers are as safe as possible when risking their lives for Canada + if we want to make certain that they are as safe as possible when risking their lives for Canada, then we need to provide them with the best equipment possible = we need to provide them with the best equipment possible

Example 2: We want the team to have the best chance of winning the championships + If we want the team to have the best chance of winning the championships, we have to choose the best players not everyone who tried out or worked the hardest = We have to choose the best players not everyone who tried out or worked the hardest

- Modus tollens

(if P, then Q)  + not Q = not P

Example 1: If the general was good, he would have won the battle + he didn't win the battle = he wasn't good.

Example 2: If capital punishment was a good policy, it wouldn't result in the death of innocent people + it has resulted in the death of innocent people = capital punishment is not a good policy

- this is a divergent argument strategy

Among other things, these can allow you to use indirect proof to prove things that are difficult to prove directly