10/20/09 BR- Who are the three “brothers” of Argument? Today: Constructing A Logical Argument – Deductive and Inductive Reasoning -Hand in “facts” -MIKVA

3 Types of Arguments: Ethos- Establishing a reason to listen or believe the speaker. E.g., “that guy is wearing a tie so he must know what he’s saying.” Pathos- appealing to the emotions of people, using emotional language or creating emotional responses in the audience. E.g., “If you don’t agree with me you must hate America.” Logos- logical reasoning (see next)

Logic- from Classical Greek λόγος (logos), originally meaning the word, or what is spoken, (but coming to mean thought or reason) is most often said to be the study of criteria for the evaluation of arguments to determine if they are fallacious or valid. - Logical argumentation uses reason and solid evidence or data.

 In this class you may use pathos and ethos in your speaking but argumentation without logos(logic) is not effective.  How many times have you seen an argument where the winner is determined by: who can yell the loudest and longest, or who can intimidate the other person (physically or by other means)  People use pathos and ethos very effectively in irrational arguments. Irrational arguments seldom produce truth.  In this class you may use pathos and ethos in your speaking but argumentation without logos(logic) is not effective.  How many times have you seen an argument where the winner is determined by: who can yell the loudest and longest, or who can intimidate the other person (physically or by other means)  People use pathos and ethos very effectively in irrational arguments. Irrational arguments seldom produce truth.

Making A Logical Argument 1st, we need to understand some terms. Premise: a fact or statement assumed to be true. E.g., Socrates is a man. Valid Argument: if the premises are true then the conclusion is true. Invalid Argument: if the premises are true but conclusions may not be true.

Deductive reasoning: reasoning in which the conclusion is necessitated by, or reached from, previously known facts. If the premises are true, the conclusion must be true. All P are Q A is P Therefore, A is Q

Examples of Valid Deductive Reasoning Since Socrates is a man,and since all men are mortal,Socrates is mortal. Since the picture is above the desk,and since the desk is above the floor,the picture is above the floor. Since an eagle is a bird,and since all birds have wings,an eagle has wings. If all parts are true the argument is said to be Sound.

Examples of Invalid Deductive Reasoning A truly left wing politician does not tolerate animal cruelty. G. Houseman thinks hitting a dog is wrong. G. Houseman is a truly left wing politician. People who do not want war in Afghanistan are weak. The President does not want war in Afghanistan The President is weak.

Inductive Reasoning More open than deductive reasoning. It is based on what can be observed and using those observations to make a general conclusion. It is not as solid as deductive(closed) reasoning. Inductive(open) reasoning is divided into strong and weak inductions or induction.

Examples of Strong Induction Reasoning All the crows I’ve seen are black therefore all crows are black. Most healthy dogs I’ve seen have 4 legs therefore all healthy dogs have 4 legs

Examples of Weak Inductive Reasoning I always hang pictures on nails therefore all pictures hang from nails. Teenagers are given many speeding tickets therefore all teenagers speed. An inductive argument is said to be cogent (good) if the conclusion is probable.

In General- Deductive Reasoning is black and white. Inductive Reasoning is shades of grey. Both can be good or logical ways to argue.

Assignment 1. Write an explanation for the following terms: Ethos, Pathos, Logos(logic), premise, valid, invalid, deductive reasoning, inductive reasoning, sound, cogent 2. Give 2 examples of both valid and invalid deductive reasoning. 3. Give 2 examples of both strong and weak inductive reasoning. You can draw a picture if it helps!

Vocabulary Journal #2 9/17-21  Ethos, Pathos, Logos, Premise, Valid, Invalid, Deductive Reasoning, Sound Argument, Inductive Reasoning, Cogent Inductive Reasoning