Reason and Logic

1
Reason and Logic

• Striking a balance between hubris and humility

2
Reason

• Making necessary connections
• Reasoning is cast in the form of arguments, which
  consist of one or more premises (reasons) leading
  to a supporting conclusion.
• Reasoning is either cogent or fallacious. It
  must started with justified premises include all
  relevant information.

3
The Law of Non-contradiction

• Aristotle
• A cannot be both B and Non B at the same time
  and in the same sense.
• E.g. Socrates cannot at the same time be man and
  nonman. He cannot be a man and at the same time
  everything else in the universe.

4
Socrates against the Sophists

• The Sophists - itinerant teachers for hire who
  taught persuasion.
• Protagoras - Homo Mensura Man, the measure of
  all things
• Socrates objection to Protagoras. (Nash, p. 231)

5
Reason, cont.

• There are two kinds of reasoning inductive and
  deductive. Inductive arguments begin with
  discrete bits of evidence and work toward a
  conclusion. Deductive begins with a
  presupposition which is then demonstrated.
• Caveat Worldviews (background beliefs) are
  always deductive!
• Often presuppositions are masked by appeals to
  reason.
• Detecting background beliefs involves reading
  between the lines.

6
Basic Syllogisms

• Modus Ponens (MP)
• (mood of affirming)
• If P then Q
• P
• Therefore, Q.

• Example
• If you lose your passport, you cannot travel to
  Germany.
• Youve lost your passport.
• Youre not going to Germany.

7
Basic Syllogisms, cont.

• Modus Tollens (MT)
• Mood of Denying
• If P then Q
• Not Q
• Therefore, not P

• Example
• If it rains, then the porch gets wet.
• The porch is not wet.
• Therefore, it is not raining.

8
Basic Syllogisms, cont.

• Disjunctive Syllogism (DS)
• Either P or Q
• Not P
• Therefore, Q.

• Example
• Either the Devil Rays or the Yankees the will win
  this game.
• The Devil Rays will NOT win.
• Therefore, the Yankees will win.

9
Learning to Detect Fallacies

• An argument is fallacious if
• Its premises werent warranted.
• Relevant information was passed over.
• The premises do not justify the conclusion
  (invalid). When the premises are bad, the fallacy
  is called a questionable premise when
  information is overlooked, suppressed evidence
  when the argument is not valid, invalid
  inference.

10
Types of Fallacies

• Argumentum ad Baculum Appeal to Force
• Ad Hominem Attacks the character not the
  argument
• Argument from Ignorance e.g. conspiracy
  theories
• Appeal to Pity
• Appeal to Authority outside a persons realm of
  specialization

11
Fallacies, cont.

• Hasty Generalization citing an atypical example
  to make a general claim
• Argumentum ad Populum arousing enthusiasm to
  win an argument
• Begging the Question assumes what one is trying
  to prove
• Complex Question loaded question
• Equivocation - argument turns on a crucial shift
  in the meaning of a word or phrase
• Red Herring sidetracking the argument
• Straw Man simplistic caricature

12
The Boundaries of Reason

• REASON AND LOGIC PROVIDE A LANGUAGE FOR
  INTERACTION AND DISCUSSION, EVEN IF NOT EVERYONE
  AGREES ON THE PRECISE USE OF AND LIMITS TO
  REASON.

13
Luther - 3 Lights of Existence

• The light of nature for common sense decisions
• The light of grace for the knowledge of God,
  otherwise unattainable
• The light of glory, mysteries now will be fully
  explained in the future.

14
Luther on naked reason alone

• It is perilous to wish to investigate and
  apprehend the naked divinity by human reason
  without Christ the mediator, as the sophists and
  monks have taught others to doThere has been
  given to us the Word incarnate, that has been
  placed in the manger and hung on the wood of the
  Cross. This word is the Wisdom and Son of the
  Father, and He has declared unto us what is the
  will of the Father toward us. He that leaves
  this Son, to follow his own thoughts and
  speculations, is overwhelmed by the majesty of
  God.