Syllogisms and Visual RhetoricSyllogisms and Visual Rhetoric

Danna PratherDanna Prather

Syllogistic form puts an argument into Syllogistic form puts an argument into three statements in order to illustrate the three statements in order to illustrate the data, claim, and warrant, but uses special data, claim, and warrant, but uses special terms to designate these.terms to designate these.

Syllogistic Form- Syllogistic Form- Categorical SyllogismsCategorical Syllogisms

All history professors are poor lecturers All history professors are poor lecturers (Major premise)(Major premise)

Dr. Fred is a history professor (Minor Dr. Fred is a history professor (Minor premise)premise)

Dr. Fred is boring (Conclusion)Dr. Fred is boring (Conclusion)

Major term: history professorsMajor term: history professorsMiddle term: poor lecturersMiddle term: poor lecturersMinor term: Dr. FredMinor term: Dr. Fred

The Categorical Syllogism - TestsThe Categorical Syllogism - Tests

1. The middle term must be used in a 1. The middle term must be used in a universal sense in one of the premises.universal sense in one of the premises.

All people breathAll people breathRachel is a personRachel is a personRachel breathesRachel breathes

This example passes - why?This example passes - why?

The Categorical Syllogism – TestsThe Categorical Syllogism – Tests

2. If a term is universal in the conclusion, it 2. If a term is universal in the conclusion, it must be universal in the premises.must be universal in the premises.

All people with cars must take driving lessonsAll people with cars must take driving lessonsMany college graduates have carsMany college graduates have carsAll college graduates should take driving All college graduates should take driving

lessonslessons This example fails – why?This example fails – why?

The Categorical Syllogism - TestsThe Categorical Syllogism - Tests

3. At least one of the 3. At least one of the premisespremises must must be an affirmative statement.be an affirmative statement.

No Republicans vote DemocratNo Republicans vote DemocratMatt is not a RepublicanMatt is not a RepublicanMatt votes democratMatt votes democrat

Fails – why?Fails – why?

The Categorical Syllogism - TestsThe Categorical Syllogism - Tests

3. If one premise is negative, the 3. If one premise is negative, the conclusion must be negative.conclusion must be negative.

No North Texans believe in the hollow No North Texans believe in the hollow earthearth

Julie is a North TexanJulie is a North TexanJulie doesn’t believe in the hollow earthJulie doesn’t believe in the hollow earth

Passes – why?Passes – why?

Syllogistic Form – Syllogistic Form – Hypothetical SyllogismHypothetical Syllogism

Major premise is concerned with an uncertain Major premise is concerned with an uncertain conditioncondition

If a universal health care system is financed through If a universal health care system is financed through income tax, it will win approvalincome tax, it will win approval

The proposed health care system is financed through The proposed health care system is financed through an income taxan income tax

It will win approvalIt will win approval

The Hypothetical Syllogism- TestsThe Hypothetical Syllogism- Tests

1. If the minor premise affirms the 1. If the minor premise affirms the antecedent (the conditional clause), the antecedent (the conditional clause), the conclusion must affirm the consequent.conclusion must affirm the consequent. If you run with scissors, you will cut yourselfIf you run with scissors, you will cut yourselfYou will run with scissorsYou will run with scissorsYou won’t cut yourselfYou won’t cut yourself

Fails – why?Fails – why?

The Hypothetical Syllogism-The Hypothetical Syllogism-TestsTests

2. If the minor premise 2. If the minor premise denies the denies the consequentconsequent, the conclusion must , the conclusion must deny the deny the antecedentantecedent..When I eat too much, I get sickWhen I eat too much, I get sick I didn’t get sickI didn’t get sick I didn’t eat too muchI didn’t eat too much

Passes – why?Passes – why?

The Disjunctive SyllogismThe Disjunctive SyllogismThe Major premise presents alternatives, The Major premise presents alternatives,

usually indicated by an “either–or” or usually indicated by an “either–or” or “neither—nor” “neither—nor” Either you will go to class this afternoon or Either you will go to class this afternoon or

you will failyou will failYou didn’t go to classYou didn’t go to classYou are going to failYou are going to fail

The Disjunctive Syllogism - TestsThe Disjunctive Syllogism - Tests

1. If the Minor premise affirms (or denies) 1. If the Minor premise affirms (or denies) one of the alternatives, the conclusion must one of the alternatives, the conclusion must deny (or affirm) the other alternativedeny (or affirm) the other alternativeEither I have to get a part time job or I will have Either I have to get a part time job or I will have

to quit schoolto quit school I didn’t get a part-time jobI didn’t get a part-time job I will have to quit schoolI will have to quit school

Passes – why?Passes – why?

The Disjunctive Syllogism – TestsThe Disjunctive Syllogism – Tests 2. The alternatives presented in the first premise 2. The alternatives presented in the first premise

must be mutually exclusive.must be mutually exclusive. Either we take our time or we will be unfairEither we take our time or we will be unfair We will take our timeWe will take our time We will not be unfairWe will not be unfair

Fails – why?Fails – why?

Either we will take our time or we will be quickEither we will take our time or we will be quick We took our timeWe took our time We were not quickWe were not quick

Passes – why?Passes – why?

The Disjunctive Syllogism - TestsThe Disjunctive Syllogism - Tests3. The major premise must include all of 3. The major premise must include all of

the possible alternatives.the possible alternatives.Jay does poor work so he must either be Jay does poor work so he must either be

stupid or lazystupid or lazyJay is not stupidJay is not stupidHe must be lazyHe must be lazy

Fails – why?Fails – why?

Enthymemes and Visual RhetoricEnthymemes and Visual Rhetoric

Enthymeme - as we learned yesterday, an Enthymeme - as we learned yesterday, an enthymeme is a rhetorical syllogismenthymeme is a rhetorical syllogism An argument where part is implied. Invites audience An argument where part is implied. Invites audience

participation.participation.

““Santa Claus is coming”Santa Claus is coming” Data for the unstated claim, You better be goodData for the unstated claim, You better be good

““Everybody graduates sometime”Everybody graduates sometime” Data for the unstated claim you will graduate alsoData for the unstated claim you will graduate also

Importance of Cultural Importance of Cultural History for VisualsHistory for Visuals

Now and ThenNow and Then