Deductive argument

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Deductive argument. Let’s Review. Induction vs. deduction. Induction : inference of a generalized conclusion from particular instances  Deduction : inference in which the conclusion about particulars follows necessarily from general or universal premises. - PowerPoint PPT Presentation

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Deductive argumentLets Review.Induction: inference of a generalized conclusion from particular instances

Deduction: inference in which the conclusion about particulars follows necessarily from general or universal premisesInduction vs. deductionNote #1:you are going to hate todays lesson.Note #2:dont worry about names. Just try to think with venn diagrams.Part I:venn diagrams with overlapFirst we draw the venn diagram.All p are q.All q are r.Therefore all p are r.

All Boston folk are from Massachusetts.All Massachusetts folk are from America.All Boston folk are from America.

Categorical syllogismIf p, then q.If q, then r.Therefore, if p, then r.

If Sam is from Boston, then he is from Massachusetts.If he is from Massachusetts, then he is from America.Therefore, if Sam is from Boston, then he is from America.Hypothetical syllogismTheyre basically the same.Whats the relationship?Next we find out where we are in the venn diagram.If p, then q.P.Therefore q.

If it is a dog, then it is a mammal.It is a dog.Therefore it is a mammal.Modus ponendo ponensIf p, then q.Not q.Therefore p.

If it is a dog, then it is a mammal.It is not a mammal.Therefore it is not a dog. Modus tollendo tollens (Contrapositive)Fallacy test!!!If p, then q.Q.Therefore p.

If it is a dog, then it is a mammal.It is a mammal.Therefore it is a dog.

What if its a bear? Bears are mammals.

Converse fallacy(Affirming the consequent)If p, then q.Not p.Therefore not q.

If it is a dog, then it is a mammal.It is not a dog.Therefore it is not a mammal.

What if its a bear? Bears are mammals.Inverse fallacy(Denying the antecedent)Finally we put it all together.If p, then q.If q, then r.Therefore, if p, then r.P.Therefore r.

If it is a dog, then it is a mammal.If it is a mammal, then it is an animal.Therefore, if it is a dog, then it is an animal.It is a dog.Therefore it is an animal.Put it all together!Part II:venn diagrams without overlapNote #3:each of these arguments has a contrapositive version. But were going to focus on the positive.First we draw the venn diagram.Either p or q.If p, then r.If q, then s.Therefore either r or s.

Abdulhayes first language is either Darija or Tashlhit.If Abdulhayes first language is Darija, then he is Arab.If Abdulhayes first language is Tashlhit, then he is Tamazight.Therefore Abdulhaye is either Arab or Tamazight.

[constructive] DilemmaLets create some dilemmas!Next we find out where we are in the venn diagram.Either p or q.Not p.Therefore q.

Abdulhayes first language is either Darija or Tashlhit.It is not Darija.Therefore it is Tashlhit. Modus Tollendo Ponens(Disjunctive Syllogism)Finally we put it all together.Either p or q.If p, then r.If q, then s.Therefore either r or s.Not p.Therefore q.

Either we legalize prostitution or we keep it illegal.If we legalize prostitution, we would be breaking Islamic law!If we keep prostitution illegal, we maintain our Islamic values.Therefore either we break Islamic law or we remain Islamic.Lets not break Islamic law by legalizing prostitution.Therefore lets remain Islamic by keeping it illegal.

Put it all together!Note #4:Be wary of false dilemmas and Reductions to the Absurd.Rework your dilemmasUsing both types of argument at the same timeHomework.Read Chapter 5 in The Debaters Guide.

For tomorrow, prove using deduction...Prove by creating your own hypothetical syllogism and modus ponendo ponens: It is wrong for a man to have more than one wife.Prove by creating your own dilemma and modus tollendo ponens: Morocco should be friends with North Korea.Draw Venn diagrams for your arguments in (1) and (2).What is wrong with this argument?... If the government cuts taxes, then the economy will improve. The economy improved. Therefore the government cut taxesIf the government invests in education, then more Moroccans have access to education. Does this mean that government investment causes the increase in access?Make an analogy between the human body and human society.Homework