Back on 23 May on ADS-L, I noted an occurrence (in speech) of “The military can do so much”, clearly intended to mean, in the context, ‘the military can do only so much’ (i.e., not everything, or not a lot, while “the military can do so much” otherwise conveys ‘the military can do a lot’). Not long after, a poster wrote:
If “can do so much” can actually mean “can do only so much”, then perhaps Churchill really meant “Never have only so few owed only so much to only so many”? I don’t think so. The sentence really needs “only” in there to make sense.
This is one version of the “X can’t mean Y” (sometimes “X doesn’t mean Y”) reaction to reports that some people sometimes use X to mean Y: flat rejection of the pairing of form X with meaning Y, usually on the basis that the objector wouldn’t use X that way (grammatical egocentrism). Note that the objection is framed as statement of fact (about the language in general, not just about the objector’s variety of the language), though actually it serves as a normative judgment (that X shouldn’t be used to mean Y).
The objector usually goes on to explain the relevant form-meaning pairings, most often by asserting a replacement for X, as in (1), sometimes adding an assertion about what X “really” means, as in (2):
(1) X’ (not X) means Y.
(2) X means Y’ (not Y).
So, the ADS-L poster says that “can do only so much” (X’) must be used instead of “can do so much” (X) to convey the intended meaning in the original sentence about the military, adding that the original doesn’t make sense. Actually, “can do so much” is quite frequent — a fact that makes it hard to unearth more examples like the military sentence — but the so of “can do so much” is an intensive rather than a simple extent adverbial.
There are examples of “X can’t mean Y” assertions all over the place. See, for example, my posting here on impact as a verb; the objector in this case insisted on have an impact on as a replacement for it. Verbings, or words that are believed to be verbings, are common targets of “X can’t mean Y” criticisms. So are many non-standard usages, or usages that are believed to be non-standard. Could care less, for instance, often gets flak on this account: the objector insists on explicit negation (type (1) assertion), sometimes adding that could care less can only mean ‘be capable of caring less’ (type (2) assertion). (There are a great many postings on Language Log and other blogs, and on ADS-L, about could care less. By the way could care less, in certain contexts, can indeed mean ‘be capable of caring less’ — “I’ve been wrestling with how to cope with this difficult situation, and I’ve decided I just could care less” — though in most contexts it will be understood as conveying negation.)
A note about “The military can do so much”: the example was from Zalmay Khalizad (who has served as the U.S. ambassador to Iraq, Afghanistan, and the UN), speaking on the radio program It’s Your World (a program of the World Affairs Council of Northern California). It’s entirely possible that Khalizad’s sentence was a simple speech error, an inadvertent omission of only, and it might be relevant that English is not Khalizad’s native language (Persian is). Larry Horn did find quite a few examples of “can do so much and no more”, which might be relevant, and he has examples of omitted only in other contexts, so for the moment I’m assuming there’s an actual phenomenon here.
It’s worth noting that I saw immediately what Khalizad intended to convey, given the context of his comments, which had to do with the limitations of military force. Context, context, context.