In this post, I discuss a dialectical norm that's often violated in the apologetics literature (though of course apologists don't have a corner on the market for this fallacy or any other). First, though, some stage-setting.

There are
three main propositional attitudes or "stances" one might take with
respect to a given proposition, P:

**1. Statements, Stances, and Evidence**
(i) Believe that P is true.

(ii) Believe that P is false, i.e., believe that ~P is true.

(iii) Suspend judgment with respect to P: neither believe that P
is true nor believe that ~P is true.

The epistemically appropriate stance for one to take with respect to P is a function of the evidence one has with respect to P. Thus, if one's basic or non-basic evidence at least slightly favors P, then one rationally ought to believe that P is true, where the strength of one's belief is proportioned to the strength of the evidence for P; if one's evidence at least slightly favors ~P, then one rationally ought to believe that P is false, where the strength of one's belief is proportioned to the strength of the evidence against P; and if one's evidence favors neither P over ~P, nor ~P over P, then one ought to suspend judgment about whether P is true, neither believing P nor believing ~P.

**2. Defeaters and Dialectical Context**

Now consider the following common dialectical context: person A asserts to another person B that statement P is true, and points B to basic or non-basic evidence E in support of P. In this context, unless B has an independent, outweighing reason to believe that P is false or unjustified (note the important qualification), B has at least some reason to adopt the stance of belief over the stances of disbelief and suspension of judgment with respect to P.

However, B loses such a reason to believe that P is true -- a reason to retain the stance of suspending judgment about P or believing that ~P -- if B has a

*defeater*for P -- i.e., an independent reason for thinking that P is false or unjustified. Now there are two main types of defeaters: rebutting defeaters and undercutting defeaters. A

*rebutting*defeater for P provides one with a reason to think that P is

*false*. By contrast, an

*undercutting*defeater merely

*neutralizes one's evidence*for the truth of P. A common form of undercutting defeater for P is a live epistemic possibility (i.e., a scenario that one's evidence can't rule out as false or unjustified) that, if true, entails that P is false.

We’ve just seen that (absent other reasons for P) a rebutting defeater for P gives one a reason to believe that ~P, and an undercutting defeater gives one a reason to suspend judgment with respect to P.

*An important implication of this is that a defeater D may fail to show that P is false, and yet succeed in indicating a live epistemic possibility that's incompatible with the truth of P. In such a case, D succeeds in showing that B ought to suspend judgment about the truth of P, even though D fails to show that B ought to believe that P is false.*

Given the frequency of such dialectical contexts, the point is worth belaboring: from the fact that D fails as a

*rebutting*defeater for P, it doesn't follow that D fails as an

*undercutting*defeater for P. Therefore, if a person A asserts that P is true, and another person B offers D as a defeater for P, it's not enough for A to show that D

*fails to show that P is false*; A must

*also*show that D

*fails to neutralize the evidence*for P.

**3. Dialectical Norms, Dialectical Fallacies, and a Common Apologetic Fallacy**

The previous points put us in a position to understand an important dialectical norm in the context of assertions. Thus, consider the following dialectical context: A believes that P is true, B does not believe P is true or justified, and A is trying to rationally persuade B that P is true. Toward this end, A offers evidence E for P. Now suppose that B considers E, but on reflection becomes aware of a defeater D for P. Finally suppose that A replies by showing that D fails to show that P is false. Should B therefore believe that P is true?

Not necessarily. For as we’ve seen, it may be that D

*fails*as a

*rebutting*defeater for P, and yet

*succeeds*as an

*undercutting*defeater for P. That is, even if A shows that D fails to indicate that P is false, A might yet fail to rule out D as an undefeated, live epistemic possibility that's incompatible with the truth of P. But if so, then even if B ought not believe that P is

*false*, B nonetheless ought to

*suspend judgment*about P.

The preceding discussion reveals a dialectical norm: in dialectical contexts of the sort sketched above, a person in A's position must not only show that (i) D fails as a

*rebutting*defeater for P, but also that (ii) D fails as an

*undercutting*defeater for P. And to assume that A discharges their dialectical obligations in offering justification for P to B in such contexts by accomplishing (i) alone is to commit a certain sort of

*dialectical fallacy*.

The fallacy sketched above occurs so frequently in the apologetics literature that I hereby label it

*the Apologetics Fallacy*. The Apologetics Fallacy is the dialectical fallacy that occurs when one assumes, in contexts of the sort sketched above, that because one has shown that D isn't a rebutting defeater for P, one has thereby shown that D isn't an undercutting defeater for P. A paradigm case of the Apologetics Fallacy can be found on pp. 291-292 of this article. And a paradigm case of the appropriate response to the Apologetics Fallacy can be found on the same pages of the same article.

## Comments

A believes that P is true, B believes that P is false or unjustified, and A is trying to rationally persuade B that P is true.

I'm wondering if you might want to modify it to:

A believes that P is true, B does not believe P is true or justified, and A is trying to rationally persuade B that P is true.

...or whatever would make B epistemically neutral with respect to P. Otherwise, by starting with "B believes that P is false or unjustified," even granting that A shows that E is not a rebutting defeater for P, the the norm for B would not be suspend judgment about P, because B already believed P false (presumably for some other reason).

MM