Logic: The Right Use of Reason

"Come now, and let us reason together," Says the LORD. Isaiah 1:18

  1. Logic is God thinking.
    1. Christ himself is represented as wisdom, logic, or right thinking.
    2. In the beginning was the Logos, and the Logos was with God, and the Logos was God. Jn. 1:1

    3. Logic is an attribute of God. God is not subject to logic in the sense that he is beneath it, nor is logic an "invention" of God. God is always utterly logical, because logic is part of who he is.
    4. Logic is the set of rules we must follow to think like God thinks, which is to think rightly.
    5. Logic undergirds morality. Otherwise, we can make no distinctions between right and wrong.
    6. Logic undergirds truth. Otherwise, we can make no distinctions between truth and error.
    7. Logic is covenantal. God himself holds us accountable for thinking rightly, because we are his creatures made in his image.

  2. Logic follows basic principles.
    1. The law of non-contradiction is the most basic law of logic:
    2. The same attribute cannot at the same time belong and not belong to the same subject and in the same respect. (Aristotle)

    3. The syllogism is the basic form of logical reasoning:
    4. Valid but untrue --
      Major premise: Dogs are brown.
      Minor premise: Rover is a dog.
      Conclusion: Rover is brown.

      Invalid but true --
      Major premise: Dogs are brown.
      Minor premise: Rover is brown.
      Conclusion: Rover is a dog.

  3. Being familiar with logical fallacies can help us spot sloppy argumentation and make us more discerning.
  4. Some examples:

    1. ad hominem -- attacking the person who holds the argument
    2. threat of force -- the person holding the argument is threatened
    3. post hoc, ergo propter hoc -- reasoning that two things closely associated in time are connected by cause and effect
    4. false dilemma -- presenting alternatives in a dilemma without acknowledging all possible alternatives.
    5. denying the antecedent and affirming the consequent --
    6. Ex: Presbyterians believe in predestination. John is not a presbyterian; therefore he does not believe in predestination (even if the premise is true, the conclusion may be false).

    7. equivocation -- terms are not used consistently throughout the argument
    8. psychogenetic fallacy -- assuming you have refuted an idea by identifying the psychological reason someone believes it
    9. poisoning the wells -- discrediting an argument by discrediting in advance the source of contrary evidence or argument


Don't You Believe It by A. J. Hoover, Moody, 1982, 132 pp. A great, easy-to-read introduction to logical fallacies.
Availability: Out of Print

A Rulebook for Arguments, 3rd ed. by Anthony Weston, Hackett, 2001, 87 pp. A short handbook on writing papers and assessing arguments.
Availability: http://www.hozien.com/mih/arg/main.htm

Logic: The Right Use of Reason by Isaac Watts, reprinted by Soli Deo Gloria, 1998. The well-known hymn-writer was also an expert logician. His text on logic was widely used for nearly two centuries and has recently been reprinted.
Availability: AU library

"Evaluating the Arguments of Experts FAQ 1.0" by N.E. Barry Hofstetter. An excellent overview of methods for analyzing expert arguments and spotting logical fallacies.
Availability: http://www.eng.auburn.edu/~sjreeves/cm/experts.html

"Critical Thinking and Logic" by Douglas Wilson. Discusses the basics of logical analysis and the difference between that and what is popularly styled "critical thinking."
Availability: http://www.home-school.com/Articles/ThinkingAndLogic.html

ChristianLogic.com. A very well-done web site presenting logic from a Christian perspective.
Availability: http://www.fallacydetective.com/

"Basic Helps for Practical Reasoning". A nice tutorial on logical argumentation in writing.
Availability: http://www.hu.mtu.edu/~dsulliva/classes/300aframe/reason.html

"The Logic Classroom". An online course on logical analysis. Links to several excellent articles. Written from a Christian perspective.
Availability: http://www.sjsu.edu/faculty/carranza/