Logical Fallicies

Logical fallacies are arguments which may sound good on the surface but which rapidly break down under scrutiny, due to faulty reasoning. These arguments are frequently deceptive or fail in some way to answer the question at hand. Entire careers have been devoted to logic, including flawed logic and I won't go into an extensive list of fallacies here. Instead, I'll briefly go over some of the most common ones and urge those who are interested to study further. (The pages at the Skeptics Guide to the Universe, LogicallyFallacious.com and Wikipedia are a good place to start.)

Quickly then, some common logical fallacies:

Ad hominem: Probably the most common in politics, an ad hominem attack attempts to discredit an argument by discrediting the person making the argument.

Ad ignorantiam: The argument that a position is true because we can't prove it is false. IE 'in an infinite universe it is likely that life exists elsewhere so you can't prove that aliens haven't visited.'

Appeal to tradition: The argument that the right way to do something is the way it has always been done or used to be done.

Argument from Ignorance or Appeal to Ignorance: This is the argument that if something can't be completely proven or made understandable to the average person, it is likely false: Example: “Evolution is complicated and riddled with holes, therefore God must have created the universe.”

Bandwagon: The idea that ideas that are popular are correct, even if the people with whom they are popular have no expertise in the area.

Begging the Question: Attempts to answer the question with a question, or at least sneak a statement not in evidence into the question or into another statement as fact. “Have you stopped beating your wife yet?” is the classic example. It assumes that the target formerly beat their wife, while asking the question. However, most examples are less obvious. If, during an abortion debate, I say “The focus should be on the rights of the baby.” I'm suggesting that we've already established when life begins and should move forward from there.

Confusing association with causation: Also known as post hoc or false cause, this is one of my favorites. This argument attempts to create a correlation between things that are unlikely to be related to one another. The website Spurious-Correlations contains some wonderfully absurd examples of this such as the relationship between the number of people who drown by falling into a pool and the number of films Nicolas Cage has appeared in that year. Of course the reverse of this, denial of causation, is another frequently used fallacy. Ex: “There is no evidence that draining the lake caused fish stocks to decline.”

False Dichotomy: Also called false dilemma assumes that there are only two possible answers to a question and if one is bad the other must be right.  “If you're not with us, you're against us” or “the only way to improve education is to raise taxes” are both examples of this type of argument.

Hasty Generalization or small sample size uses a small or even anecdotal sample size to draw broad conclusions. Ex: “Bob and Larry both played the harmonica and both had cancer so playing the harmonica must cause cancer”. This fallacy is commonly used in policy discussions and is one of the root causes of stereotypes. Think, for example, of many of the statements made about Muslims and terrorism in the last few decades.

Naturalistic Fallacy: The idea that because something is natural it is good and morally right. For example: 'Because sex is the means of reproduction in nature, homosexuality is wrong.” In this fallacy god can be substituted for nature and is used by some religious groups to argue against using medicine to treat disease, because disease is naturally occurring.

Slippery Slope: This is the argument that any move in a particular direction runs the risk of leading to the most extreme possible outcome. Example: “Legalizing marijuana will put us on a slippery slope toward legalizing heroin” or “raising taxes will put us on a slippery slope toward government controlling all wealth”. It assumes that there are no moderate positions or that people don't have the choice of avoiding extremes once starting down a path.

Straw Man: This approach involves restructuring a person's argument into something that is easier to argue against. This may involve pretending an exception is the rule, focusing on a non-central part of the argument or otherwise distorting a statement into something that is easier to defeat than the person's actual argument. If, for example, person A supports easier immigration and person B points to a crime committed by an immigrant then argues that person A supports that crime they are creating a straw man. Stating that a person is pro-cancer because they do not support funding a particular research project would be another example.

As I said, there are hundreds of noted fallacies but if the ones above suddenly disappeared from our political conversations, they would become much more interesting and productive.