Mastering Logical Fallacies. July 20, 2020

I’m baffled that this kind of book is still being published these days. It’s not so much of a guide to mastering fallacies as an encyclopedia-style list. A more comprehensive list can be found over at Wikipedia, where the fallacies are presented in a less dull format, with more examples and related fallacies.

I also have a problem with the “comeback” sections, where the implied scenario is a good-faith debate where the participants will accept a well-reasoned argument. There are potential issues with nearly every comeback in this book. For example, the “Anonymous Authority” entry says that

There’s no problem with appealing to authority when that alleged authority is in fact an expert on the topic in question. So, if I say, “Black holes emit radiation,” I can justify this by appealing to the authority of Stephen Hawking.

This is a weird example to use because I doubt scientists would speak in such certain terms, including Stephen Hawking. In the case of Hawking radiation, although there’s a theoretical mechanism for it there’s only very weak experimental evidence for it. It’s far from well established that black holes emit radiation.

This is not unusual; science is full of uncertain things, with varying degrees of uncertainty. But the notion of an “authority” doesn’t allow for that. This illustrates a general problem I have with focusing on fallacies as something to look for in a debate: because it removes the context of what’s being talked about, it’s not a very convincing way of striking down an argument. It’s often used to compensate for lack of knowledge in the topic or lack of ability to formulate a proper retort.

Another example: “Appeal to the Moon” is the argument that if we’ve done some difficult task, then surely we can do another, also difficult, task. (“We’ve been to the moon, so why can’t we cure cancer?") The comeback goes:

First, point out that your opponent’s argument is simply invalid: the fact that one difficult thing has been achieved doesn’t mean that a different difficult thing may also be achieved. After all, the difficulties associated with the latter feat remain unaffected by the achievement of the first feat. You should then point out just how great these difficulties are; perhaps putting a man on the moon is in fact relatively simple compared to curing cancer.

The first point is this paragraph is simply pointing out that this fallacy is a fallacy; I’m not sure this is very effective in a debate. The second point is just begging for an exploration of how hard a mission to the moon is and what the specific difficulties with cancer research are! You can’t claim in good faith that one is easier than the other without getting into specifics.

This fallacy also illustrates another problem I have with classifying fallacies: most of them essentially amount to “B does not follow from A”, also known as non sequitur. Often, the non sequitur fallacy is explained with such blatant examples that I can only imagine the person making the fallacious claim as acting in bad faith. But in practice, non sequitur is more nuanced: sometimes your opponent isn’t able to formulate their reasoning clearly, and sometimes you just fail to be convinced. The solution to that is to debate the points until they’re refined enough that it’s either clear that B follows from A, or that it does not.

This might not be your goal if you just want to win the debate. But if your goal is winning then I don’t see why you should be pointing to fallacies at all. It’s useful to know about them, but more in terms of how you can use them to your benefit. Appealing to emotion can be quite effective, for example.

If your goal is to learn, then do not invoke fallacies in a debate. And do not read this book.