Doctor : You should quit smoking.

Reminder: there are many ways in which reasoning can go wrong; that is, there are many kinds of mistakes in argument. It is customary to reserve the term “fallacy” for arguments that, although incorrect, are psychologically persuasive. Some arguments are so obviously incorrect as to persuade and deceive no one. But fallacies are dangerous because most of us are, at one time or another, fooled by some of them. A fallacy is often defined as a type of argument that may seem to be correct, but that proves, on examination, not to be so.

Professor Snodblatt has argued against the theory of evolution. But Snodblatt is a pompous, egoistical windbag, and a card-carrying member of the Communist Biker’s Association. I absolutely refuse to listen to him. • Personal attack (ad hominem)

Senator Biddle has argued that we should outlaw violent pornography. Obviously, the Senator favors complete governmental censorship of books, magazines and films. Frankly, I’m shocked that such a view should be expressed on the floor of the United States Senate. It runs counter to everything this great nation stands for. No senator should listen seriously to such an outrageous proposal. • Straw man fallacy – the logical pattern of the straw man arguments is this: • 1. X’s view is false or unjustified [but where X’s view has been unfairly characterized or misrepresented]. • 2. Therefore, X’s view should be rejected.

Secretary to boss: I deserve a raise in salary for the coming year. After all, you know how friendly I am with your wife, and I’m sure you wouldn’t want her to find out what’s been going on between you and that sexpot client of yours. • Appeal to force – It is a psychological threat. The appeal to force fallacy usually accomplishes its purpose by psychologically impeding the reader or listener from acknowledging a missing premise that, if acknowledged, would be seen to be false or at least questionable. This example can be interpreted as concealing the following false premise: • If I succeed in threatening you, then I deserve a raise in salary.

Doctor: You should quit smoking. Patient: Look who’s talking! I’ll quit when you do, Dr. Smokestack! • Ad hominem (inconsistency) – The logical pattern of these arguments is this: • X fails to follow his or her own advice. • Therefore, X’s claim or argument should be rejected. • But this reasoning is clearly wrong. Arguments are not good or bad because of who offers them but because of their own intrinsic strengths or weaknesses. You cannot refute a person’s arguments simply by pointing out that he or she fails to practice what he or she preaches.

Yes, Jill argues for deconstruction. But her mind is so open her brains are falling out. You can safely ignore whatever she has to say. • Personal attack (ad hominem). Note: No argument against deconstruction is given.

All of the really cool, intelligent, sophisticated students take critical thinking. Therefore, you should, too. • Argument from popularity

“Buy Michelin tires. Don’t risk your children’s safety by buying inferior brands.” • Scare tactic

“Yes, obviously the President’s strategy in Iraq is working. The liberal media in this country just can’t stand the thought of us winning this war.” • Red herring

I bet my husband will be glad that I was out drinking with my friends until 2 AM because he probably needed some time alone. • rationalization

Officer: Excuse me, sir. Do you know how fast you were going? Driver: I never get over the sight of you mounted policemen. How do you leap down off the horse's back so fast? And you must have them well trained, not to run away when you dismount. • Apple polishing

Person 1: Smoking increases the risk for developing lung disease. • Person 2: "That may be true for you, but it is not true for me.“ • Subjectivist fallacy

Doctor : You should quit smoking.