Using "sānē" v. "certē" v. "profectō"?

Question

The dictionary definitions of these three words aren't particularly helpful in figuring out when to use which one.

Lewis Elementary's definition of sānē includes

2. indeed, doubtless, by all means, truly, certainly, of course, right, very

Certē, meanwhile, includes

3. really, surely, assuredly, actually, certainly, as a fact

Finally, profectō is

actually, indeed, really, truly, assuredly, certainly.

This is very frustrating from a living-Latin perspective. Obviously, we use "certainly" in a lot of different contexts, but I wish the dictionary had more to say about which contexts call for which word. From what I can tell, for example, one use of sānē is as a concessive "to be sure"—"He's loathsome, to be sure, but he's still your brother." But I can very easily imagine that "sure" in "Surely you can see that I'm right about this" would call for a different word.

The example sentences provided in Lewis & Short aren't much help either. In Nōn est ita, jūdicēs, non est profectō, profectō could be meant in so many different ways that I find it unhelpful as a guide. ("It's not like that, judges; [you may think it's like that, but] in fact it's not." Or "It's not like that, judges; it most assuredly isn't." And so on.)

Can anybody provide any guidance, however incomplete, in the matter of different uses of these words? It's possible that the clearest thing to do would be to provide English examples illustrating the different uses (i.e., "You would use certē if you were trying to say something like, 'Blah blah blah certainly blah blah,'") but I'm happy for anything that helps.

Answer 1

Ramshorn's Dictionary of Latin Synonyms, pg. 113, has a helpful entry on the four related terms certe, certo, profecto, and sane:

1. Certe: certainly, of a thing; at least, if it applies to a given case;

   Si Deus scit, certe illud eveniet. Cic.
   Quod eæ nostris literis certe scire potuistis. Id.
   Homines mortem vel optare incipiant, vel certe timere desistant. Id.

2. Certo: with certainty, of the conviction of him who knows:

   De quo te non dubitare certo scio. Id.

3. Profecto: assuredly, in fact, assuring something as fact:

   Non est ita, judices, non est profecto. Cic.

4. Sane:

   • entirely so, verily ;

     Sane vellem potuisset obsequi voluntati tuæ. Cic. ;

   • in "concessive style," it signifies, may it be so :

     Hæc sint falsa sane. Id. 198.

Walter's Latin Prose Composition for College Use offers the following guidance:

profecto, sane, certe, certo, etc.: certainly; any way; these particles simply lend emphasis.

1. profecto: (pro + facto = "for a fact") is the strongest— as a matter of course,
2. certe: precedes and lends assurance to the whole thought,
3. certo: [lends assurance] to the predicate, as such, alone; and
4. sane: concedes, grants something as true, and so = yes.

This entry also ends with an interesting note that might be relevant to the inherent issue of translation in your question: "Oftentimes our 'indeed,' 'really,' etc., are fully translated merely by placing the verb in an emphatic position."

To add some simple personal observations to the above:

1. Certo is less common as an adverb, and seems to be used overwhelmingly with scio to signify my own confidence in what I am saying. It thus means something like "I know for certain" whereas certe scio, for instance, is more like "It is certain that I know...".
2. Profecto appears to be the most objective word for expressing factual certainty, as witnessed in its origin from pro + facto. Walter suggests that it means something closer to "obviously," but I think this depends on context.
3. Certe means certainly as well, but much like English "certainly" is often juxtaposed with another idea that is not certain. It can thus mean something like "at least" or "of course" with something potentially more ominous to follow.
4. Sane appears to be the most subjective and, in my experience, often is paired with the subjunctive as a concession and means something more like "even". "Let us accept that X, but..."

And last, a quote from Cicero that seems to juxtapose and contrast two of these words nicely:

quid habet enim vita commodi? quid non potius laboris? sed habeat sane; habet certe tamen aut satietatem aut modum. (Cicero, De Senectute, 84)

For what advantage does life have? Or rather, what toil does it not have? But even if it should have advantages, nevertheless it certainly either reaches satiety or comes to an end.