Informal Fallacies

Logical Fallacies Poster“Fallacies are unsound arguments that are often persuasive because they usually appeal to our emotions and prejudices and because they support conclusions that we want to believe.” (Chaffee, The Philosopher’s Way, 24)

Let’s consider three species of fallacies: those of false generalization, causal fallacies, and fallacies of relevance.

I.  Fallacies of False Generalization

Previously I presented the inductive reasoning technique called empirical generalization, in which our broad conclusions are drawn from the reasoning we’ve made based on observations of a limited sample. This group of fallacies spring up when this technique is not done appropriately or in an irresponsible manner.

Hasty generalization: these occur when we make general conclusions too quickly and without sufficient data points to sustain our conclusion.

E.g. My boyfriends have never shown any real concern for my feelings. I conclude that all men are insensitive, selfish, and emotionally superficial.

Sweeping generalization: in this instance we fail to take into account that there are exceptions to the rule and thereby sweep these exceptions that don’t fit our conclusion into the generalized pool.

E.g. Vigorous exercise contributes to overall good health.
Therefore, vigorous exercise should be practiced by recent heart attack victims, people who are out of shape, and women who are about to give birth.

False dilemma: This is also called an “either/or fallacy” or a “black-or-white fallacy.” These occur when we are asked to choose between two extreme alternatives without being able to consider another option.

E.g. Either we are completely free to make choices or everything we do is determined by factors outside our control and we have no freedom whatsoever; there is nothing in between.

II.  Causal Fallacies
These occur when we fail to identify the appropriate cause.

Questionable cause: these occur when we present a causal relationship for which no evidence exists.

E.g. Astrology. Superstitions about walking under ladders, or breaking mirrors.

Misidentification of the cause: it is often the case that we aren’t clear on what has caused something.

E.g. Drug dependence and emotional difficulties. Or, failure in school and personal problems. Which causes which?

Post hoc ergo propter hoc: the translation of this phrase from Latin is “after it, therefore because of it.” This points to situations where two things occur close to one another and we assume that there is a causal relationship between the two things.

E.g. You grow a beard during baseball season and your favorite team wins the World Series.

Slippery Slope: this one gets deployed frequently and sometimes tag teams with the false dilemma maneuver. With the slippery slope fallacy we are told that one undesirable outcome is inevitably going to lead to a worse outcome, which will in turn lead to an even worse outcome. While this outcome may indeed occur, there is no causal guarantee that it will happen.

E.g. You don’t do your homework and you bomb the test, and you fail out of high school, and you can’t get a decent-paying job, and you can’t quite shake the feeling of being a failure and so over time no one wants to hang out with you and so stop going outside until you get kicked out of your apartment and you’re homeless and you die alone and without anyone aware you’d ever lived.

III.  Fallacies of Relevance
Very frequently fallacious arguments make appeals to factors that have nothing to do with the merits of the arguments being offered. Instead of presenting strong evidence, we substitute these false appeals.

Appeal to authority: In these instances we are asked to agree with an argument because an authority figure has said it must be so.

Appeal to tradition: similar to the above, here we are asked to maintain a previous position simply because it is the status quo.

Bandwagonism: this is also called peer pressure. Just because it’s popular, it doesn’t mean it’s accurate or true.

Appeal to emotion: There is a whole family of arguments here.
Appeals to pity, “give me an A or I’ll lose my scholarship,”
Appeals to fear, “vote for me or ISIS is going to kill Grama,”
Appeals to vanity, “only someone as smart as you can see the wisdom of my point.”

Personal attacks: These are often very effective because folks hearing them ignore the issues at hand and instead focus on the personal qualities of the opponent.
These are also called

  • Ad hominem: arguments that are “to the man” rather than the issue discussed.
  • Poisoning the well: wherein we try to ensure that any water (argument) drawn from our opponent’s well (mind) will be treated as undrinkable (unsound).

Red herring: This is also called a “smokescreen” or “a wild goose chase.” In this fallacy we divert attention away from the relevant matters by committing to and introducing irrelevant matters.

E.g. I don’t think grade inflation is a problem in education. Everybody wants to be liked and teachers are just trying to get students to like them.

Tu quoque: This is also called “whataboutism.” This is an appeal to hypocrisy and is like the red herring strategy in that it commits to irrelevant information

E.g. What about Hillary’s emails? What about Obama’s drone policy?

Attacking a Straw Man:  This is a common form used that is based on giving the impression of having overturned an opponent’s argument, while actually overturning an argument that was not presented by one’s opponent.