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# One fallacy down, several more to go

The Internet is good for some things. It certainly makes some types of research much easier than they once were. You once had to look up reference materials in a card catalog, find the material on your library's shelves, and then read through it to see if it contained the information you were looking for. This often took quite a while. It certainly took more time than just typing a few words into Google and clicking on "Google Search."

The Internet is also very useful when you start teaching your kids about logical fallacies. Pick almost any blog that discusses politics and you'll see more examples of logical fallacies than you used to see in your entire life in the pre-Internet days. When I stumble across examples of these fallacies, I often feel the urge to post things like "This is a good example of what's often called a 'false dilemma' or 'bifurcation fallacy.' Please refer to your college textbook on logic for more information, or click on this link to learn why your argument makes no sense whatsoever."

Maybe I'll actually do it some day.

One of the common logical fallacies is the so-called genetic fallacy, which says that an idea shouldn't be accepted or rejected based on its origin instead of on its merit. I suspect that a careful analysis of this particular fallacy would show that it's not really a fallacy, and this is because of the connection  to Bayesian reasoning.

As I've mentioned before, Bayesian reasoning leads us to weighing peoples' opinions based on what we know (or think that we know) about them. Liberals are likely to misrepresent and distort the facts when talking about conservatives and their points of view and conservatives are likely to misrepresent and distort the facts when talking about liberals and their points of view, for example. Because of this, we know that we can't trust what we hear, so the reasonable thing to do is use Bayesian reasoning that evaluates the chances of what we hear being true given everything else that we know (or think that we know). This means that the genetic fallacy is really nothing more than Bayesian reasoning at work.

Now it seems that Bayesian reasoning is a generalization of the usual Aristotelian logic that reduces to it in the special case that the hypotheses are either true or false. There's even an interesting book by E. T Jaynes, Probability Theory: The Logic of Science, that describes exactly how this works. So if Bayesian reasoning is consistent with logic and the genetic fallacy is consistent with Bayesian reasoning, I'm inclined to believe that the genetic fallacy isn't really a fallacy after all. A logical fallacy, after all, is an error in reasoning, and it looks to me like the genetic fallacy really isn't an error. Instead, it's just taking advantage of all the available information to put new information into a useful context.

That just means that I won't feel compelled to point out a small fraction of the logical fallacies that I see on the Internet. Luckily, there are still enough others out there to keep me entertained for the foreseeable future.