When should we trust an argument from authority? What about a fact or premise supported by a quote from an authority? The following will attempt to answer these questions in a way that is helpful.
First, one should only accept an appeal to authority if one is within her own field.
I will give two examples of this, one obvious and another one from real life. Suppose there is an award-winning current events journalist who gives an opinion on the philosophy of history. This in and of itself is not fallacious. However, if within an argument or discussion a person says, “This journalist says X and Y about the philosophy of history,” his appeal to authority is fallacious. Why? Because the authority isn’t really an authority at all, at least when it comes to the subject at hand.
The second example is one I have actually seen. When reading an article opposing evolution, a quote from a physicist was made to the effect of, “there are too many biological problems with evolution for it to be plausible.” This may be so, and the physicist may have had wonderful arguments and reasons for making this claim. Unfortunately, the article’s author merely offered this in support of his claim that evolution has biological problems. Although the authority was at least a scientist, it simply won’t do as a mere appeal because he isn’t a scientist in the relevant field!
Second, one should not accept an appeal to authority if that alone is the basis for the argument or proposition.
In most cases, it is a bad idea to say something like “Jesus rose from the dead. Dr. So and So says so in his book.” That is a rather obvious example. Less obviously, however, are examples relating to science (and other subjects which laymen do not readily understand). As in our real-life example in the first major point, it would be fallacious to assail evolution on the singular quote from the scientist, even if the man was a biologist! Why? Because in this case we have moved from a mere appeal to authority to the authority becoming the argument itself.
Finally, appeals to authority are justified when used to show specific points/evidences or when access to the relevant information is sufficiently limited.
We cannot know everything for ourselves firsthand. Hence, anything we accept without firsthand knowledge is done at least partially on a basis of appeal to authority. We are completely rational to trust that the archaeologist who says they have discovered the ancient city of
(barring any reason to distrust him), and should not be skeptical. It is important to know exactly what constitutes the correct appeal to authority (like “Doctors agree that smoking increases your chances of getting cancer”) and fallacious appeals (like “Professional athletes say smoking increases your chances of getting cancer,” or “A doctor says cancer causes smoking”). If you are very familiar with the correct ways of thinking, the poor reasoning will be more evident, even if you are unfamiliar with the particular name for that fallacy. Jericho
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