In the original context, the alleged desirable ambiguity was the ability to concisely omit information--that is, to say "people" instead of "men and women". Tabooing 'ambiguity', I'd frame this as a matter of having words for large sets rather than requiring speakers to construct them out of smaller sets, and say that this is a good thing if those sets are commonly referred to.
On a similar note, there can be intensions whose extensions are not agreed upon--"good" and "right" spring to mind. At first I thought it would be necessary to have words for these, but upon reflection I'm not sure. Could we replace them with more specific words like "right according to classical utilitarianism" or "right according the ethics of the person this word relates to"?
Sounds like the difficulty here is in the difference between ambiguous and vague or general.
On a similar note...
lojban handles that by defining words on a fill-in-the-blank basis, where you can leave out any (or all) of the blanks to be less specific. "good", for example, is defined "*[object/event] is good for [beneficiary] by [standard]*". A speaker/writer may fill in as many of the details as (s)he feels are necessary to communicate. As the author, you may be as vague about the specifics as you like, but what you actually said always selects for an exact, unique semantic region.
This was going to be a reply in a discussion between ChristianKl and MattG in another thread about conlangs, but their discussion seemed to have enough significance, independent of the original topic, to deserve a thread of its own. If I'm doing this correctly (this sentence is an after-the-fact update), then you should be able to link to the original comments that inspired this thread here: http://lesswrong.com/r/discussion/lw/n0h/linguistic_mechanisms_for_less_wrong_cognition/cxb2
Is a lack of ambiguity necessary for clear thinking? Are there times when it's better to be ambiguous? This came up in the context of the extent to which a conlang should discourage ambiguity, as a means of encouraging cognitive correctness by its users. It seems to me that something is being taken for granted here, that ambiguity is necessarily an impediment to clear thinking. And I certainly agree that it can be. But if detail or specificity are the opposites of ambiguity, then surely maximal detail or specificity is undesirable when the extra information isn't relevant, so that a conlang would benefit from not requiring users to minimize ambiguity.
Moving away from the concept of conlangs, this opens up some interesting (at least to me) questions. Exactly what does "ambiguity" mean? Is there, for each speech act, an optimal level of ambiguity, and how much can be gained by achieving it? Are there reasons why a certain, minimal degree of ambiguity might be desirable beyond avoiding irrelevant information?