By Nat Murphy

 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

 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?

 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.

 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?

 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.

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

 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

 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

 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.

 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?

 Do you think you could have a sign that applies to one of the fallacies?  Do you think that signs are a good way to persuade people in argumentation?  What ways can you think of to avoid fallacies in your writing?