Motte and Bailey

A common fallacious form of argument is that known as the "motte and bailey," also sometimes called the "bait and switch," though the archaic term "motte and bailey" is more evocative for those of us who aren't engaged either in retailing products or in fishing as a regular matter.

The term "motte" suggests a strong defensive position (not to be confused with a "moat," though obviously related -- we'll get to that). The motte is the raised earthwork in front of a castle. It may have a wooden palisade on its crest.

The "bailey" is a pleasant and less militarized zone, perhaps a courtyard or market, outside of the protection of the motte.  A moat, or perhaps a dry ditch, might exist protecting the whole motte-and-bailey complex.

The idea is that the whole complex is defensible against small numbers of foes. But against a larger more determined attack, when a raid becomes a battle, the bailey might have to be abandoned as the knights retreat to the castle, behind the protection of the motte.

As a fallacious form of argument, the term refers to two distinct contentions which are advanced as one.

Consider the ancient controversy over the question "why is there something rather than nothing?" One possible ANSWER to Q is that "something exists" is a logically necessary truth. One possible corollary to THAT is that something has always existed, so there was no beginning of all things for metaphysicians or cosmologists to puzzle about.

There are other answers. Heck, the physicist Lawrence Krauss thought the question important enough to deserve a book length answer, A UNIVERSE FROM NOTHING (2012), which didn't argue from logical necessity but from quantum fluctuations, the uncertainty principle, etc.

I'm interested in the motte and bailey today, so here is my example. One might affirm the tautology, "Existence must be existence" as a necessary truth defended by the motte -- the logical principle, that A equals A. On the other hand one might be suggesting also that "Something must necessarily exist!"

That existence is a logical necessity is the bailey. That existence must be itself is the motte. The bailey (a logical foundation for the existence of this universe) is desirable to its proponents but difficult to defend, except by periodical retreats behind the safety of the motte.

In retail terms, you are lured into the store by the notion of an impregnable answer to an ancient question.  But that isn't really what is on offer. There is a bit that addresses the ancient question, and a bit that is impregnable, but they aren't the same.