Nature And Logic

Philosophy 103: Introduction to Logic
The Nature of Logic
Abstract: Some of the uses of logic are illustrated, and deductive arguments are briefly distinguished from inductive arguments.

I. Logic is the study of the methods and principles used in distinguishing correct from incorrect reasoning.
B. Logic differs from psychology in being a normative or a prescriptive discipline rather than a descriptive discipline.
  1. I.e., it prescribes how one ought to reason; it's not concerned with how one actually does reason.
  2. Logic is concerned with laying down the rules for correct reasoning.
  3. Consequently, logic seeks to distinguish good arguments from poor ones.
II. How Logic helps reasoning:
A. "Practice makes better."   Some examples of how this course can help reasoning about the world are as follows.
  1. Consider this syllogism:
  All followers of Senator Jones are in favor of higher taxes.
All communists are in favor of higher taxes.
All followers of Senator Jones are communists.
  It will become easy for us to recognize the fallacy in this argument as the fallacy of the undistributed middle term.
  2. Consider this informal argument:
  In spite of the large number of UFO spottings that can be attributed to weather conditions and known aircraft and other factors, there are hundreds of sightings that cannot be accounted for. Hence, we can safely conclude that UFO's exit.
  Consider this counter-example:
  In spite of the large number of quarters put under kid's pillows which can be attributed to sneaky parents, brothers, sisters, and so forth, there are hundreds of cases which cannot be accounted for. Therefore, the tooth fairy exits.
B. As well, this course can help with "the negative approach"—that we avoid errors by being aware of them, e.g., being aware of common formal and informal fallacies.
  1. Consider the passage, "Napoleon became a great emperor because he was so short." In this short argument, the...