PHL 3305 Lecture 8

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General Introduction [to the Logic Text] (GILT)

Why?

Reasons for studying logic:

• orders and clarifies thinking
• sharpens skills in reading and writing
• gives power to prove things
  • ability to convince/persuade others
• conducive to
  • pursuit of happiness
  • understanding faith
  • political life of citizens
• enables one to
  • test authority
  • recognize contradictions
  • pursue wisdom and truth
  • obtain certainty

Innate Reasons:

• Question itself hints at answer: Why study Logic? ... Why?
  • Because we want to be able to answer with Because...

Wisdom and Reason

Relating cause to effect

From Aquinas:

• "It belongs to wise men to put things in order"
  • understand relation of parts to the whole
• "Wisdom is the highest perfection of wisdom"

"Methodological Naturalism" - a way of thinking how we should do natural science

Sciences have a tendency to run away with each other if not kept in check by each other.

• Arts and sciences are ordered to one end: our happiness.
• Aquinas: Our intellect is to the first causes as an owls eyes are to the light of the sun, so we pursue it last
  1. Logic
  2. Mathematics
  3. Philosophy of Nature
  4. Moral Philosophy
  5. Divine Science (first causes)

What is logic?

• "logic" comes from Greek λόγος, meaning "word" or "reason":
  • trivium = arts of word: grammar, logic (in the proper sense), rhetoric
• dialectic
  • Plato has broad definition (synonym for "the philosophical way of life")
    • What a thing is and how it differs from other things, yada yada...
    • Plato has a tactic of dramatizing dialectic in the form of a "play"
    • n.b. Don't trust everything Socrates says, but don't discredit everything he says either.
  • Aristotle has very narrow definition...
    • A tool for reasoning
    • Dialogue between two individuals: a questioner and answerer
    • Specific rules to follow: Start with premises someone is willing to grant you (ἔνδοξα, "common opinions").
  • When you see the word used by someone somewhere, be aware which definition is being used
  • a conversational form of logic
  • demonstrative reasoning

The madman is not the man who has lost his reason. The madman is the man who has lost everything except his reason.Chesterton, G. K. Orthodoxy

Modern vs. Classical Logic

modern logic

highly specialized

logic in its "purest" form

useful for analysis of distinct forms of argument (not tied to nature or reality)

looks for consistency of terms within argument

classical logic

arises from ordinary perception of the world

grounds reasoning in truth

Logic: Art and Science

Logic is an art

• it requires training to become good at it
• The "art of reasoning"
• Human beings naturally desire to know stuff
  1. sensation
  2. memory
  3. experience
• The "art of arts" ... reason is applicable in every other art (and usually in everyday life)

Logic is a science

• The "science of reason"
• Aquinas points out three operations of reason or acts of the intellect:
  1. simple apprehension - understanding simple objects
     • definition: a genus and specific difference
       • genus - what type of thing it is
       • specific difference - what makes it different from other things in that genus
  2. composition and division - relate simple objects to one another
     • also called judgement
     • composition - unites terms through affirmation (e.g., "all men are mortal", uniting "men" and "mortal")
     • division - separates terms through negation (e.g., "no horses are dogs", separating "horses" and "dogs")
     • result of process is called a statement or preposition
  3. discursive reasoning - Putting statements together to arrive at new truths
     • syllogism - combines two premises that entail a third conclusion
     • can be correct/incorrect according to form (logical structure of argument)
     • can be true/false according to matter (actual content of syllogism)