For the fine art of deli meat identification, look elsewhere.

The Fine Art of Baloney Detection is an essay by Carl Sagan in his seminal work against pseudoscience, The Demon-Haunted World. In the essay, he gives advice for devising conclusions, as well as advice for avoiding rhetorical and logical fallacies. Together, the set of warning signs for common fallacies constitutes what Sagan very politely calls a "Baloney Detection Kit". Sagan categorizes the logical and rhetorical fallacies as below. Here is given the type of fallacy, a definition of each, and an example from the current internet.

Sagan makes a few suggestions about the "tools" a skeptic should keep ready in their Baloney Detection Kit. These are not merely measures to identify bad arguments, but constructive ideas about how to come up with better alternatives:

Type of fallacy Definition Example

Ad hominem An ad hominem argument attacks the messenger, not the message itself. "The secular geologists can't hear or see the message [about creationism] because of their academic indoctrination in anti-Biblical, naturalistic, uniformitarian assumptions. The reason that most Christian geologists can't see it is the same, plus the fact that they have believed the scientific establishment more than the Bible that they claim to believe is the inspired, inerrant Word of God."[1] This doesn't say anything about the argument of creationism, but rather the scientists.

Argument from authority This type of argument relies on the identity of an authority rather than the components of the argument itself. "Young earth creationists believe that the Book of Genesis is historical in nature and that Bible exegesis warrants a six-day creation with each day being 24 hours."[2] The argument is that the Bible is the Word of God, so everything in it must be true by definition.

Argument from adverse consequences Saying that because the implications of a statement being true would create negative results, it must not be true. "If we allow people to believe the evolutionist doctrine that they are nothing but animals, human civilization will be DESTROYED in a tidal wave of immorality!"

Appeal to ignorance If something is not known to be false, it must be true. We refer the reader to the Answers in Genesis page on the non-constant speed of light.[3] It's interesting because the creationists who propose how the speed of light has changed have backed off from their claims, and now the website is claiming that a few scientific articles (actually two) make the possible claim for slight variations in the speed of light (much too small to explain the chronology problem), therefore it must have been different in the past, and therefore the whole speed of light is questionable and must be thrown out. Never mind the consequences if the speed of light changed from fast to slow; atoms and the energy of photons would be so messed up that the early-creation Earth would probably fry any young Earth. Of course, the creationist just put a "time dilation field" around it, and everything is OK. Never mind that there is no evidence for it.

Special pleading Stating a universal principle, then insisting that it doesn't apply to your assertions for some reason. Everything MUST have a cause. Except God.

Begging the question / assuming the answer This occurs when a statement has an unproven premise. It is also called "circular reasoning" or "circular logic". "A man from a primitive culture who sees an automobile might guess that it was powered by the wind or by an antelope hidden under the car, but when he opens up the hood and sees the engine he immediately realizes that it was designed." — Michael Behe[4] Most of Behe's arguments say, if it looks designed, it must be so. This assumes the answer to the question.

Observational selection Looking at only positive evidence while ignoring the negative. Remembering the instances where you predicted that it would rain for an event, while ignoring all of the instances where you predicted rain and there was none.

Statistics of small numbers Using small numbers in order to report large percentage increases "Our membership has increased 100% in the last year." (In reality, this could mean that the one prior member has recruited an additional member, and says nothing about the total number of members. An organization with 100,000 members which grows by 100% has increased its membership by 100,000, a far cry from increasing membership by one more member.)

Misunderstanding of the nature of statistics Ignorance about central statistical assumptions and the definition of metrics. Astonishment when confronted with the fact that half of all people have an IQ below 100, a value that was defined as the median score in the first place.

Inconsistency Being inconsistent in any form, especially as in holding double standards. Evolution isn't good science, since it can't be proven. Intelligent design is good science, because it can't be disproved.

Non sequitur Latin for "it does not follow." "Living specimens of orders of animals that were believed to have been extinct for millions of years have been found before, such as the Diatomyidae Squirrel, [ sic ] the Wollemi Pine and the Coelacanth [and therefore dinosaurs co-existed with humans]."[5] The no-longer-extinct pine trees, Diatomyidae and fish have no real connection to the extinct (non-avian) dinosaurs.

Excluded middle, or false dichotomy Portraying an issue or argument as having only two options and no spectrum in between. Arguably, "Either you are with us, or you are with the terrorists." George W. Bush[7]

Short-term vs. long-term Assuming a current trend has remained constant throughout its history and will continue to do so in the future, even though no evidence suggests such an extrapolation is justified. Currently the Earth's magnetic field is decreasing in intensity. At this rate, according to the time-frame supposed by evolution, the field would have originally been so powerful as to render earth inhospitable. Evidence, of course, suggests that the earth's magnetic field not only waxes and wanes, but even switches polarity every so often.

Slippery slope, related to excluded middle Saying something is wrong because it is next to or loosely related to something wrong. If gay marriage is legalized, all of our children will be converted to homosexuality, and Satan will win.

Confusion of correlation and causation Just because two phenomena happen simultaneously does not mean that one causes the other. People who go to church are happier than others. Thus, God makes people happy if they go to church.

Straw man Misrepresenting a position to make it easier to criticize. "Evolutionists believe that everything just poofed into existence!"

Suppressed evidence and half-truths Drawing an unwarranted conclusion from premises that are at least in part correct. The fact that atmospheric scientists still have minor disagreements about the specifics of global warming is misrepresented as indicative of a lack of consensus about the existence of the phenomenon. So it is with evolution, which also is host to minor disagreements as to how it happened, e.g. punctuated equilibrium. Neither of these disagreements challenge their overall validity.