June 18, 2012 by mattfradd
If you frequent websites such as YouTube or Facebook, (or if you’ve been following the comment thread on my article “Catholic, Gay & Feeling Fine”) you’ve read the exchanges that take place on these forums. Sometimes they are intelligent and substantive, but often they resemble two toddlers squabbling: “Did too.” “Did not.” “Did too.”
If we are to heed the instruction of our first pope, which is to “always be ready to make a defense to anyone who calls you to account for the hope that is in you” (1 Pet. 3:15), we must have at least a basic understanding of argumentation. We must know what constitutes a strong argument and what constitutes a weak one.
What an argument isn’t—and is
An argument is not an assertion such as, “God exists”. Nor is an argument merely a contradictory assertion such as, “No, he doesn’t.” An argument is not a quarrel, a fight, or a disagreement. an argument, properly speaking, is a set of propositions called premises from which the person who is making the argument seeks to establish a conclusion.
Types of arguments
There are two main types of arguments: deductive and inductive. A deductive argument is one in which, provided the premises are true and the logic sound (valid) the conclusion follows necessarily. Here’s a classic example of a deductive argument:
Premise 1: All men are mortal.
Premise 2: Socrates was a man.
Conclusion: Therefore, Socrates was mortal.
Do you see that if both of the premises are true and the logic valid, then the conclusion follows necessarily? If someone disagrees with the conclusion, then he must, on pain of irrationality, argue that one of the premises is false or that the logic unsound.
Here is an example of an argument with true premises, yielding a true conclusion, yet with bad logic:
Premise 1: All men are mortal. Premise 2: Paris is the capital of France. Conclusion: Therefore a beaver is a large semiaquatic broad-tailed rodent.
An inductive argument is one in which a generalization is made based on specific instances so that, provided the premises are true, the conclusion probably follows. For example:
Premise 1: Socrates was a Greek.
Premise 2: Most Greeks ate fish.
Conclusion: Therefore, Socrates ate fish.
Though the conclusion here gives us probable certainty, it does not give us the absolute, logical certainty that a deductive argument gives.
Understanding what constitutes a sound argument—and what does not—will allow you to clear away the smoke of impassioned language that is sometimes used in faith related dialogues so that you can see clearly the argument your opponent is trying to make.
Later this week we’ll take a look at 5 common logical fallacies and how to detect them!