Logical Fallacies.

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Presentation transcript:

Logical Fallacies

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.

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.

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.

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?

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.

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.

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

http://www.logicalfallacies.info/