Michael Sean Quinn*
            In a deposition not long ago, I was asked whether I though an insurance company defending an insured had a duty to be truthful with the insured.  I answered that I was sure that the insurer must not lie to its insured and should not makes statements to the insured which, if it were thinking reasonably, would at least probably believe were false, and/or should believe are false.  “All well good,” said the depositioner “but I asked you whether the insurer had a duty to be truthful. Isn’t it that case, that the insurer must not be untruthful with its insured?” 
Without thinking, I simply blurted out, “Well, that depends on the meaning of the word ‘untruthful.’”  I felt like Bill Clinton. The depositioner then said, “OK, tell me about that, please.”  By then it had already dawned on me that there was a kind of trap built her questions and my answers.  I came to realize that in a subtle way, ordinary language with respect to telling the truth, being truthful, lying, untruthfulness, and being untruthful is not a perfectly symmetrical set but a bit of a pile epistemological ideas.
To be sure, to tell lies is to be untruthful, and to assert a true proposition to another is to be truthful, or—at least—it sounds like it. But maybe not. What if I assert to someone a true proposition, which I know he will not understand, am I being truthful? I am inclined to think not, at least under many circumstances.  If I am right about this, then being truthful is different than simply asserting truths. On the other hand, if I am in the presence of a person, and I have a true proposition in mind but don’t assert it, am I being untruthful?  Obviously not. 
But suppose the proposition pertains to a service I am rendering this person, so it is one he needs to hear about. Am I being untruthful? Surely not, if I simply forget to mention it, or I mistakenly believe that this is not something he needs to know, and it will just upset him, if he hears it. On the other hand, if I systematically and intentionally refrain from telling him truths relevant to serving him, then it might sound like I am being untruthful.  One might call this an “untruthful omission.” It surely would be being untruthful if the person for whom I am a steward asked me questions but I intentionally manage to avoid giving him answers, though never out-and-out lying.  This point, in at least extreme cases, is nicely illustrated by idea of half truths.
In any case, these points illustrate the odd fact that one can be truthful in a literal sense (“He never speaks anything but the whole truth.”), but also be untruthful in a less literal but also important sense (“He doesn’t always tell the whole story, even to her.”)  Of course, not telling the whole story can be an accident, a blunder, a pattern resulting from habit, or systematically poor memory or something specifically intentional. These various grades are significant because an isolated accidental happenstance would not count as a person being untruthful, whereas cases resulting from deliberate intent would. 

In dawned on me in that deposition that my interlocutor was trying by semantic distinctions to set up a rhetorical disaster zone for his target and that I was being enlisted as his foot-in-mouth soldier.  I learn new things about legal dialogue, legal discourse, arguments of law and fact, and about the subtleties of the use of language in and near courts all the time.