Just a few more thoughts for our gentle readers who may have come in late or don't want to muddle through the previous pages.
Carl Sagan presented his baloney detection kit as a way to evaluate new ideas.
He introduced it this way:
“If you’re so inclined, if you don’t want to buy baloney even when it’s reassuring to do so, there are precautions that can be taken; there’s a tried-and-true, consumer-tested method.
“What’s in the kit? Tools for skeptical thinking.
“What skeptical thinking boils down to is the means to construct and to understand, a reasoned argument and—especially important—to recognize a fallacious or fraudulent argument. The question is not whether we like the conclusion that emerges out of a train of reasoning, but whether the conclusion follows from the premise or starting point and whether the premise is true.” (The Demon-Haunted World, p. 210)
Here are some of the tools Sagan suggested.
• Wherever possible there must be independent confirmation of the facts.
• Encourage substantive debate on the evidence by knowledgeable proponents of all points of view.
• Arguments from authority carry little weight (in science there are no "authorities,” at best there may be experts).
• Spin more than one hypothesis—don't simply run with the first idea that caught your fancy. If there’s something to explain, try to think of all the different ways it could be explained, then think of the tests whereby you might disprove each of the alternatives.
• Try not to get overly attached to a hypothesis just because it's yours. Try to think of ways to prove it false. What are the best arguments against it?
• Quantify, wherever possible. Being able to assign numerical values to whatever you are attempting to explain makes it easier to evaluate and to choose among competing hypotheses. In the absence of the ability to make quantifiable measurements, the task becomes much more difficult.
• If there is a chain of argument every link in the chain must work, including the premise.
• Occam's razor - if there are two hypothesis that explain the data equally well choose the simpler.
• Ask whether the hypothesis can, at least in principle, be falsified (shown to be false by some unambiguous test). In other words, it is testable? Can others duplicate the experiment and get the same result?
Additional issues are:
Conduct control experiments - especially "double blind" experiments where the person taking measurements is not aware of the test and control subjects.
Check for confounding factors—separate the variables.
Common fallacies of logic and rhetoric
Ad hominem - attacking the arguer and not the argument.
Argument from "authority." Authorities have been wrong in the past and will be wrong in the future.
Argument from adverse consequences (putting pressure on the decision maker by pointing out dire consequences of an "unfavorable" decision).
Appeal to ignorance (absence of evidence is not evidence of absence). This is the claim that whatever has not been proven false must be true, and vice versa.
Special pleading (typically referring to god's will). This is done to rescue a proposition that is in trouble. One of the classic examples is the appeal to divine mysteries to explain how a perfect deity who is good could allow evil to exist.
Begging the question (assuming an answer in the way a statement or a question is phrased). For example: “How did ‘God’ create the universe?”
Observational selection (counting the hits and forgetting the misses). This is a favorite trick of psychics and others who claim paranormal powers. They always remind us of any prediction that is even close to the mark. They never mention those that miss wildly.
Statistics of small numbers (such as drawing conclusions from inadequate sample sizes).
Misunderstanding the nature of statistics (President Eisenhower expressing astonishment and alarm on discovering that fully half of all Americans have below average intelligence!)
Inconsistency (e.g. military expenditures based on worst case scenarios but scientific projections on environmental dangers thriftily ignored because they are not "proved").
Non sequitur—"it does not follow"—the logic falls down. “America has prospered because we are a ‘Christian’ nation.”
Post hoc, ergo propter hoc - "it happened after so it was caused by" - confusion of cause and effect.
Meaningless question (“What happens when an irresistible force meets an immovable object?”). If there is such a thing as an irresistible force, there cannot be such a thing as an immovable object. The opposite is also true.
Excluded middle—considering only the two extremes in a range of possibilities (making the "other side" look worse than it really is). Example: Either morality comes from ‘God’ or it’s based on individual whims and wishes.
Short-term v. long-term—a subset of excluded middle ("why pursue fundamental science when we have so huge a budget deficit?").
Slippery slope - a subset of excluded middle - unwarranted extrapolation of the effects (give an inch and they will take a mile).
Confusion of correlation and causation.
Straw man—caricaturing (or stereotyping) a position to make it easier to attack. Darwin’s theory of evolution by natural selection must be false because it fails to explain the origins of life. In fact, Darwin never claimed to explain the origins of life and the subject is not part of the theory of evolution at all. Theories about the origin of life are classified as theories of abiogenesis.
Suppressed evidence or half-truths.
Weasel words—for example, use of euphemisms for war such as "police action" to get around limitations on Presidential powers. Talleyrand said, “An important art of politicians is to find new names for institutions which under old names have become odious to the public.”
(From The Demon-Haunted World, p210-216)
The argument starts:
- global climate change is happening
- mankind is causing it
- it's going to be bad
The defense is full of errors. How many can you spot?
One side starts with a set of foregone conclusions. One side admits doubt about the conclusions and the possibility of other explanations.