Two Kinds of Reasoning

1
Two Kinds of Reasoning

• Chapter 2

2
Arguments General Features

• Review What is an argument?
• God exists.
• This is a statement, not an argument.
• God exists. It is as plain as the nose on your
  face.
• This is a more emphatic statement, but it is
  still not an argument.
• God exists. There are no atheists in foxholes.
• From a logical standpoint, these two statements
  are not related.

3
Arguments General Features

• I think God exists, because I was raised a
  Baptist.
• This is not an argument, rather it is an
  explanation about why someone believes in God.
• God exists because something had to cause the
  universe.
• This is an argument because it has a premise that
  supports a conclusion.

4
Unstated Premises and Conclusions

• Of course tennis players arent weak, in fact,
  no athletes are weak. This argument is missing a
  premise.
• All true democrats believe in freedom of speech,
  but there are some Americans who would impose
  censorship on free expression. This argument is
  missing a conclusion.
• We will talk about this much more in chapter 8.

5
Deductive arguments

• We talked about deductive arguments in the last
  chapter. However, there are more things to know
  about deductive arguments.
• Validity if it isnt possible for the
  premise(s) to be true and the conclusion to be
  false.
• When the premise(s) of an argument are true and
  the argument is valid, then it is a sound
  argument.
• We will talk about this much more in chapter 8,
  too.

6
Inductive arguments

• The premises of inductive arguments dont prove
  their conclusions they support them.
• For example
• The vast majority of entertainers are
  extroverts. Dave Letterman is an entertainer.
  Therefore David Letterman is an extrovert.
  Inductive argument. The premises support the
  conclusion, but they do not attempt to show that
  the conclusion necessarily follows from the
  premises.

7
Exercises 2-5.

• (A few exercises from 2-5, page 57-58 of the
  text)
• Which of these items are intended to be deductive
  demonstrations and which are intended to provide
  inductive support?
• 1. No mayten trees are deciduous, and all
  nondeciduous trees are evergreens. It follows
  that all mayten trees are evergreens.
• 2. Mike must belong to the Bartenders and
  Beverage Union Local 165, since almost ever Las
  Vegas bartender does.
• 3. Ive never met a golden retriever with a
  nasty disposition. I bet there arent any.
• Please turn to page 56 of your textbook.
  Identify the premises and conclusion in the first
  5 exercises in exercise section 2-3.