Is it wrong to use "last" instead of "latter" to address the second element in a list of two?

Question

I am reviewing an academic paper written by somebody else.

At some point in this work the second element in a list of two elements is addressed as "the last". I immediately reached for the red pen to change it into "the latter", but then the doubt came: is there any rule prohibiting the use of "last" instead of "latter" when addressing the second in a list of two elements?

I am not looking for guidelines regarding the use of former/latter/foremost/hindmost/..., there is plenty of resources already answering this kind of questions (see here, or here), I just would not like to correct something that is not wrong in the first place. Ideally a reference to a grammar that explains why using "last" in this circumstance is wrong would make for a perfect answer.

Answer 1

Prescriptions about former/latter (for two items) and first/last (for more than two items) are common in style guides, but I have found nothing prohibiting last when referring to two items. To show the closest I've found, here is Garner's Modern English Usage, p. 407:

former; latter. A. Application. If these terms are to be used at all (and it’s often best to abstain), they should apply only to a series of two. The former is the first of two, the latter the second of two. In contexts with more than two elements, first should be used rather than former, last rather than latter ....

You perhaps observe that "latter rather than last for contexts with two elements" does not occur. More generally, I have not been able to find a clear prohibition against last used to refer to the latter of two elements. For instance, Fowler gives functionally identical advice.

As far as editing practice goes, I would make a stylistic decision for the publication on whether to be more prescriptive (if former and latter fit this situation, don't use other items instead) or descriptive (if they chose last and it's technically at the end of a group of two, so be it). I would not be surprised if an academic copy editor had a style sheet prescribing that rule.

Sources:

Fowler, H. W., and Jeremy Butterfield. Fowler's Concise Dictionary of Modern English Usage. Third edition, Oxford University Press, 2015.

Garner, Bryan A. Garner’s Modern English Usage. Fourth edition, Oxford University Press, 2016.