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Logical Fallacies.

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Presentation on theme: "Logical Fallacies."— Presentation transcript:

1 Logical Fallacies

2 Error in Reasoning Starts with an argument… Which needs support…
If solid evidence is provided (facts), then it is a solid argument. If the evidence lacks validity for any reason, likely the “evidence” supporting the argument contains a logical fallacy.

3 How do we identify logical fallacies?
Critical Thinking!! Look for reasoning that is disconnected… Some appear sound: Deductive Reasoning: And it is if the truth of the premise leads to the truth of the conclusion Ex: a) All men are mortal b) Socrates was a man c) Socrates was mortal If the probability of validity is very high, it is a solid argument.

4 Valid Argument This is a deductively valid argument because it is impossible for A and B to be true, but C be false. Grey area: Religion/Spiritual Beliefs Ex: Jesus was a man. So, with the same deductive reasoning Jesus would be mortal, but all of Christianity is built on the belief that Jesus was and is God.

5 Question Could the Puritans’ religious beliefs have led to a deductively valid argument, due to some element of their belief system, or was their reasoning for persecuting men and women for being witches logical fallacy?

6 However, the conclusion is not supported by the evidence.
Inductive Reasoning So, if deductive reasoning leads to a solid argument, then what consists of a logical fallacy? It may start with a strong premise (and from the start appear to be true). However, the conclusion is not supported by the evidence.

7 Strong v. Weak Strong: (1)Every day to date the law of gravity has held. Therefore: (2) The law of gravity will hold tomorrow. Weak: I forgot to study for today’s quiz and still made an A. Deciding not to study for quizzes will get me good grades.

8 Where do logical fallacies occur?
The Crucible Half-Hanged Mary Politics Commercials And…

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