Using Logic

Written by Leon Felkins, 10 Feb 1996

Revised 1/8/10

"If the world were a logical place, men would ride sidesaddle. " - Rita Mae Brown.

• Basics

  Suppose you tried to play a game in which the rules were arbitrary: each individual could set their own and could change them anytime. I doubt that you would want to play this game for very long. Most of us would rather play games that have a fixed set of rules that do not change during play. Logic is fundamentally a set of rules that we agree to use in our discussions. It is more than that, but that aspect of it will be of great help in our discussions and our thinking.

  A simple explanation of logic -- suitable for the level we need here -- is given in Compton's Interactive Encyclopedia:

  Because of the number of possible interpretations, the subject matter of logic has variously been defined as "the laws of thought," "the rules of right reasoning," "the principles of valid argumentation," and "the study of truths (true statements) based solely on the terms they contain."
  The last definition, and probably the least known one, implies the curious notion that the "facts" of logic need not necessarily coincide with the everyday realities of life. If a statement, or proposition, is analyzed solely within itself, the statement may be logically true even when contradicted by sense, experience, or knowledge. Or it may be logically true, even if the facts it presents are doubtful or uncertain. This is true because logic depends, first of all, on the ability to move from a premise to a conclusion based on the premise.
  . . . Such a use of so-called true statements, without regard for the everyday realities, may seem frivolous and insignificant. In fact, such logic, which moves from premise to premise in a strict and logical sequence, is quite useful. . .

  ---------------------------------------------------------
  Excerpted from Compton’s Interactive Encyclopedia
  Copyright © 1994, 1995 Compton’s NewMedia, Inc.

  Here is another definition of logic extracted from a text book (The Art and Science of Logic by Daniel Bonevac, Mayfield Publishing Co., 1990):

  Logic is the study of correct reasoning. Aristotle (384-322 B.C.) founded the discipline of logic as a system of principles on which all other knowledge rests. Indeed, logic pertains to all subjects, since people can reason about anything they can think about. Politics, the arts, literature, business, the sciences, and everyday problems are all subjects open to reasoning. Sometimes the reasoning is good; sometimes not so good. People use logic to tell the difference.
  . . .
  The twentieth century has witnessed remarkable advances in science and technology that have improved the lives of vast numbers of people. These applications of scientific method required a great deal of good and highly sophisticated reasoning. But the twentieth century has also suffered the results of reasoning gone astray [political and social disasters].
  . . .
  Logic is not the study of how people do reason, but how they should reason. We might put this point differently by saying that logic does not describe the psychology of reasoning, with its flashes of insight and oversight; it prescribes methods of justifying reasoning, that is, for showing that a given bit of reasoning is proper. [emphasis added]

  An example of such logical reasoning (deductive logic) is:

  All cows are purple.
  Wilma is a cow.
  Therefore, Wilma is purple.

  Note that the argument is true regardless of the truth of the two premises. The use of deductive logic is extremely powerful in science, mathematics and philosophy.

  You do not have to be a mathematician to use logic. Mathematicians and scientists often use symbols to represent logic because it facilitates obtaining a conclusion and is not nearly as subject to error as ordinary languages are. It is important to realize, however, that whether an argument is stated in ordinary language or in mathematical symbols, has nothing to do with its truth or falsity. It is tragic that many intelligent people reject the rules of logic because they see it as simply a mathematical artifice.

• Abuse of Logic

  While you don't have to be a mathematician, you do need to be careful with logic. It is easy to make mistakes. Some examples of fallacious logic are given in this essay, Most common informal fallacies of logic. The worst of the fallacious arguments is the "False Dilemma" (False Dichotomy) argument. This is commonly used by the hustlers and the ignorant. The argument is based on the idea that "given the claims A and B, if A is false, B must be true". For example, let A be "we need to increase taxes" and B be "children and old people will have to eat dog food". If I am opposed to A that doesn't mean I agree with B. As I said, this argument is typically used by hustlers such as politicians and the news media. People that are taken in by this argument are simply stupid, of which, apparently, there are many.

  Another example of "False Dilemma" that is having serious consequences for society is that "since science is not absolutely certain of many of its claims and does make mistakes, mysticism must be correct". No, the fact that science is sometimes in error does not in any way establish that mysticism is correct. Mysticism must be evaluated on its on claims. When this is done, we find that, relatively, science is far superior to mysticism in explaining the world around us.

• Common Illogical Actions

  • Means instead of Consequences

    It has become popular in these times to base decisions on means rather than consequences. I suspect that we ordinary folks have learned this tragic abuse of logic from the politicians. A simple example of this logic is the situation where the little old lady gives to some fund that claims to feed starving children in Africa and feels good about it even if advised that the money or the food it could buy never makes it to the starving children. Our politicians routinely take actions that never really achieve any useful consequences. They do this by passing laws that do harm to all of us but more than likely has no impact on the stated problem.

    Another aspect of this problem is the "easy out" we humans have taken in ignoring the consequences of taking no action. The consequences of taking no action are just as likely to do harm (or good, in some cases) as taking an action. For example, suppose you were driving on a dark night through a rough neighborhood. As you round a curve, you see a young child wandering in the roadway, possibly lost. At first you start to stop, but then decide to move on as it is a dangerous neighborhood and the whole thing could be a setup. You drive on. A few seconds later the child is hit by another car and killed.

    If you had hit the child with your car, you could be tried for manslaughter and possibly go to prison. Yet, the law and possibly your conscience, generally will not hold you accountable for taking no action. Yet the consequences are the same. An interesting book that goes into some detail on this peculiarity of law in which we are usually not held accountable for consequences but only for certain actions is Bad Acts and Guilty Minds by Leon Katz (University of Chicago Press, 1987). An enlightening essay on this subject, temporarily accessible on the internet, is "Nonconsequentialist decisions" by Jonathon Baron.

  • Self-Deception

    It is an apparent paradox that humans can deceive themselves. How can this be? How can the mind know what it believes to be true but, somehow, change that belief? Yet, self-deception appears to be very common. For more on this peculiarity, read Alfred R. Mele's essay, "REAL SELF-DECEPTION".

• Decision Theory

  A related field of processes of thinking is Decision Theory. I will add more on this subject in the future, but for now you may want to consult this simple introduction to Decision Theory.

• Conclusions

  The current unpopularity of logic is having tragic consequences. Imagine a trial in which the jury is not capable of, or simply declines to use, logic. Actually, you don't have to imagine; just look at some the recent notorious cases! Imagine political decisions being made that affect the lives of millions of people but are illogical. Imagine a criminal system that panders to the criminals more than to the victims. Of course, you don't have to imagine any of these as they are with us today. Such is the price we pay for promoting the idea that logic is only for mathematicians and the rest of us can "reason" any cockeyed way we want to.

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