How To Detect Bullshit, Part 3

And now the thrilling conclusion to my "How To Detect Bullshit" series...

My previous installments of "How To Detect Bullshit" dealt with the scientific method in general, and some specific guidelines for rational evaluation of claims. In addition to all of the above, it's helpful to be aware of certain logical and rhetorical fallacies, which are indicators of faulty logic. Beware of arguments that contain the following fallacies and, of course, avoid using them yourself.

Ad Hominem - Latin for "to the man", an ad hominem is an attempt to discredit someone's argument by attacking them personally, instead of the argument itself. For example, "why should we pay attention to Freud's theories - he was a coke head!" or, "Hitchens isn't trained in theology, therefore his arguments about God aren't sound!" Arguments should be assessed on their own merit.

By the way, not all personal criticisms or insults count as ad hominems in the fallacious sense - it's only a fallacy if you use such an attack as a substitute for a proper criticism of the argument.

Argument From Adverse Consequences - Sometimes things that are true are difficult to deal with. The consequences of facts have no bearing on whether or not those facts are true. The argument from adverse consequences states that "X cannot be true, because the consequences of X would be undesirable." For example, "there must be a god, because otherwise my life would have no meaning."

Appeal to Ignorance - "We don't have a good understanding of X, so it must not be true," or, "hypothesis X isn't well-supported; therefore, alternative hypothesis Y is true." For example, "I don't know how else to explain the strange lights I saw last night; therefore it must have been aliens!"

Another form of this could go the other way: "nothing has falsified the Big Bang theory, so that proves it." We don't know all there is to know, and so all scientific theories are considered to be tentative - even well-supported theories like the Big Bang. In other words, science is always open to new evidence (and so should we all be).

Special Pleading - If someone claims that their proposition is exempt from certain rules or criticisms - and they don't give a reasonable explanation why - they are making use of "special pleading".

For example, theists often take the following line of reasoning: "everything that exists has a cause; the universe exists, therefore it had a cause." Their conclusion, of course, is that God "caused" the universe. But if God exists, mustn't he therefore have had a cause as well? What "caused" God? The theist's response to this challenge is invariably a version of special pleading, which claims that God is exempt from the rules of causality - for no reason other than the assertion that god is uncaused.

Begging the Question - This fallacy occurs when your argument's conclusion is contained within the premise. It's a form of circular reasoning, which essentially takes the form of "X is true, because X is true."

For example, "I know Bigfoot exists, because last fall I saw Bigfoot in the woods." The conclusion here is that Bigfoot exists. The premise is built on the assumption that Bigfoot exists, without any rational or empirical support. Your claim may very well be true, but it is up to you to demonstrate that what you saw was, in fact, Bigfoot.

Observational Selection - "Counting the hits and forgetting the misses." This one's really easy to fall in to. I suspect it's also the basis for a lot of woo-woo "alternative" medical treatments, and the success of such "services" as astrology.

For example, when recalling the statements made during a psychic "reading", it's easy to remember the specific times when the psychic said something that was true about you ("hits"), even if they were greatly outnumbered by untrue statements, or "misses". A talented psychic will also know how to make their misses less conspicuous, and even turn them in to hits once in a while.

Statistics of Small Numbers - Examples from Sagan: "They say 1 out of every 5 people is Chinese. How is this possible? I know hundreds of people, and none of them is Chinese. Yours truly." Or: "I've thrown three sevens in a row. Tonight I can't lose."

Non Sequitur - Latin for "it doesn't follow". When your premise does not logically lead to your conclusion. Many of the other fallacies listed above are special instances of non sequitur.

Post hoc, ergo propter hoc - Latin for "it happened after, so it was caused by." A "before and after" sequence of events is not a sufficient condition to establish causality (although it is a necessary one). For example, "You know who used to cut class? Jimi Hendrix. You know what happened to him? He died! choking on his own vomit!"

Meaningless Question - For example, "If God is supposed to be omnipotent, can he create a rock so big he can't lift it?" Such questions are simply exercises in logical contradiction. Another type of question that may be meaningless deals with meaning itself: "What is the ultimate meaning of life?" may turn out to be as meaningless as asking "what is the sound of gravity?"

Excluded Middle, or False Dichotomy - Considering only the two extreme possibilities, when a continuum of intermediates is also available. For example, "if you aren't for us, you're against us."

Slippery Slope - Related to the Excluded Middle fallacy. If you're claiming that A will inevitably lead to Z, you must back up that claim by establishing the intermediate steps, not by merely implying them.

For example, here's Pat Robertson in fine form, speaking against gay marriage: "And what about bestiality, and ultimately what about child molestation and pedophilia? How can we criminalize these things and at the same time have constitutional amendments allowing same-sex marriage among homosexuals?"

Confusion of Correlation and Causation - As any science 101 student should be able to tell you: correlation is not an indicator of causation. If, for example, all you know is that "when A increases, B also increases", you simply don't have enough information to conclude that "A causes B". It could easily be the other way around. Or there could be some third variable that is causing changes in both A and B.

Here's an amusing example that I did not invent: Since the 1800s, the number of pirates in the world has steadily decreased, while the temperature of the planet has steadily increased. A statistical analysis reveals that the two variables are strongly correlated. Therefore, the decline in piracy around the world has clearly caused global warming.

Straw Man - When someone uses a "straw man", they present a distorted (usually weaker) version of their opponent's argument, and attack that argument rather than the original one. This is a lowly debating tactic, and an indicator of intellectual dishonesty.

For example, to summarize this bullshit anti-evolution video: "evolutionists theorize that the universe is the result of random chance, plus time. The evolutionist's formula is a myth!" -- Well of course it's a myth, because the "evolutionist's formula" presented here is a straw man argument created by this particular intellectually dishonest young-earth creationist. The theory of evolution deals with the multiplying of species on our planet by means of natural selection, and has zero to do with the universe creating itself out of nothing. By the way, I included a link to the original video so you can verify that I'm not presenting a straw man.

Anyone who learns to recognize and avoid these fallacies will be able to detect bullshit from a mile away.