The Fallacy of Mediocrity

I collect logical fallacies in the same way that other people might spot birds or collect stamps. Logical fallacies are interesting not only as tools for avoiding errors in thought and argument but also as a window into how we think. The very reason that we need to catalog them is that they seem compelling. Just as optical illusions fool the eye, logical fallacies are cognitive illusions that fool the mind.

Over the last decade, I've been a frequent participant in online newsgroup discussions. Such forums are virtual breeding grounds of various types of fallacy. In addition to the ordinary fallacies of Ad Hominem and Post Hoc, Ergo Propter (which is usually just called a Post Hoc fallacy), you also get things such sightings as the Non Causa Pro Causa fallacy, the fallacy of Reification, and the ever popular fallacy of the Extended Analogy.

In my time on these forums, I have noticed a fallacy that does not seem to have an entry on any of the lists of fallacies that I'm familiar with. I have decided to call it the Fallacy of Mediocrity (henceforth, the FoM). I also call this the "Just" Fallacy for reasons that will be explained.

In formal terms, the fallacy is the assumption that any given member of a set must be limited to the attributes that are held in common with all other members of the set.

I'm guessing that you're wondering what the hell that's supposed to mean. As is often the case, an example might help: "If humans are just animals, then why should we be concerned about justice? We should just obey the law of the jungle."

The fallacy is that the implication that we are animals means that there must not be anything which distinguishes us from any of the other animals. Obviously, this is fallacious. An easy example of a distinction is our cultivation of fire. The fact that we can use fire does not logically imply that we are not animals (unless you adopt a very exotic definition of the term "animal" that excludes fire use) but the fact that other animals don't use fire doesn't mean that we can't be fire users. Fire use is simply a unique attribute of the human animal – one of many.

The reason that I also call the FoM the "Just" Fallacy is that the word "just" (as a synonym for only) is a typical indication that you may be dealing with the FoM: "If people are just chemicals, how can we think? Chemicals don't think!"

The reason that the FoM appeals to people is that it typically carries an emotive subtext that biases our intuitions. If you argue that a particular stance says that we're just animals, the implication is that there's something bad and demeaning about being an animal. This lends itself to the false assumption that being an animal would imply that we should not have certain human qualities since there must not be anything to distinguish us from the animals. Since we all know that we do have traits which set us apart, this leads to the erroneous conclusion that we must not be animals after all. Although the chain of reasoning is based upon a false premise, it can, never the less, seem compelling.

Strictly speaking, the FoM is just a special case of a category error which is where an entity is considered to have aspects or features that it does not have. The concept of a category error is, however, fairly broad (and may, itself, be considered a example of the Fallacy of Equivocation). The errors defined by the FoM, however, are of a particular type. I have seen enough FoM type errors over the last ten years to believe that it does, in fact, deserve its own description particularly since it results in a very specific sort of intuitional bias, as I have described above.