Signs and Fallcies

1. Signs and Fallcies By Nat Murphy

2. Reasoning From Signs • Involves drawing conclusions about something based on a physical sign • Mystery Novels • Conclusions based on such reasoning are based on circumstantial evidence because the sign alone cannot be evidence • The conclusion from the sign is what matters

3. Example • President Franklin Delano Roosevelt used reasoning from signs in his estimate that the attack on Pearl Harbor had been planned for some time. • This was based on the distance from Japan to Hawaii. • If you wake up in the morning and see that the ground is wet you may assume that it rained, but could the sprinkler system not just have been turned on?

4. Deceptions in Signs • Your conclusions may be logical, but they are not always correct. • So you must use reasoning from signs only in conjunction with other methods in order to confirm your case.

5. Tests For Argument From Sign • The major test for sign is whether or not the sign applies in all cases. • Basically, can you draw multiple conclusions from the same sign? • Does the sign require other components to be true?

6. Example • The average temperature of the Earth has risen over the past decades, since the inception of the modern machine and the use of fossil fuels. • One could look at the evidence and say that global warming must exist with the reasoning based on the sign that the temperature has increased. • However this sign may no prove that higher temperatures equals the global warming effect. • Further investigation is required.

7. Fallacies This is the divider slide in case you couldn’t tell.

8. Fallacies • There are three major types of major types of fallacies in logic. (That I will be addressing) • Hasty Generalization • Ad Hominem Arguments • Appeals to Popular Appeal

9. Hasty Generalization • Basically the whole “Don’t judge a book by its cover” argument. • In this situation conclusions are based on incomplete evidence • The observer has not examined all the possibilities. • For example, if you meet someone and assume their behavior to be defined as a function of their clothing. • You have not examined this person in the whole, just simply in one aspect

10. Ad Hominem Arguments • This is taken from the Latin phrase which means “Against the man” • These are arguments made against the person rather than the person’s arguments • This is readily evident in politics • Politicians readily attack their opponents character as opposed to the issue at hand. • This makes no sense because everyone can make good sound arguments even if their character is questionable.

11. Appeals to Popular Opinion • This is also called the Bandwagon Fallacy • This idea suggests that something is true simply because everyone says it is. • Often this is defined by public polls • Just because everyone likes something does not mean it is good for the population • Think about marijuana- Popular polls would show it to be a great success, but is it really the best for society?

12. Quiz! • Do you think it is possible to have a sign that falls under one of the fallacies? • What steps could you take in persuasion to make sure that you do not succumb to any of the fallacies? • What arguments from sign could you make for the Green Revolution topic?