In one post, a commenter maintained that the phrases "I did my best" and "I did the best I could" don't mean quite the same thing.
If it is true, what is the fine difference between the two?
I'm the one who made that comment. I am a native English speaker. I will explain what I was thinking, though in preparing this answer I may have talked myself into accepting that there is no difference in meaning.
Provided that "do one's best" is an idiom, is "I did the best I could" a proper phrase to be used at all?
I don't see why one phrase being an idiom has anything to do with whether another phrase is "proper", but in any case "I did the best I could" is a common expression.
is there really a fine difference between the two?
The two phrases can be used interchangeably. The meaning is very similar, or, arguably, the same: the shared idiomatic meaning is that I tried as hard as I could.
The reason I said that they don't mean quite the same thing is that in my experience when someone says "I did the best I could", what they mean but aren't saying explicitly is "I did the best I could in the circumstances". For example, in preparing dinner I did the best I could with the ingredients available in the refrigerator, but if I'd had time to go to the supermarket I could have bought more ingredients to cook something much nicer. Or in running a race I did the best I could given that I had the flu, but usually I'm a better runner than that.
"I did my best" can be and often is used in exactly the same way: that in the circumstances I could not have done any better. But sometimes the literal meaning is intended, that the result is the best I am capable of in any circumstances - I have come across this intended meaning occasionally. I have never heard "I did the best I could" used to mean the best I'm capable of in any circumstances. So that is the subtle difference that I had in mind.
I accept that not everyone will see any difference between the two. As I said at the beginning of my answer, I'm not sure that I see a difference anymore either. The two phrases do feel slightly different to me, but I can't explain that any better than what I've already said. Sorry, I did the best I could...
When I hear I did the best I could I think the speaker might be implying that he could have done better but there was something external (something that wasn't up to him) that affected his performance. So he did the best he could but maybe he could have done better if he was given better tools (i.e. I did the best I could with the given tools which is not my absolute best). Another example would be "I did the best I could under those specific conditions and circumstances".
On the other hand we have I did my best which I think is just more generic. It just says that I did my best with no reference to anything that may have affected my performance. So it could be the best I could in the given context or just my absolute best.
I did my best to think of an example where there would be a meaningful difference between the two, but I'm coming up empty.
Both phrases talk about putting the utmost effort into some endeavor, be it a sculpture, a race, a homework assignment, or some other task.
Sorry I couldn't say anything more than that. I did the best I could.
I did the best I could to think of an example where there would be a meaningful difference between the two, but I'm coming up empty.
Both phrases talk about putting the utmost effort into some endeavor, be it a novel, a skating routine, a Stack Exchange answer, or some other task.
Sorry I couldn't say anything more than that. I did my best.
If anyone can point out a difference between Answer 1 and Answer 2, we might be able to unlock the mystery. Grammatically, I suppose, they may have a slightly different feel to them; I think I did the best I could works better at the end of a sentences than at the beginning, so I'm somewhat partial to Answer 1.
Insofar as meaning goes, though, I can't discern even a slight difference.
It's very subtle, but I see a distinction.
There's also the setting of expectation:
Further to the above, variations of each phrase can be used to comment on someone else's work:
Turning each of those into a question:
I did the best I could means you did your best in the given
scenario and that was not the one you've imagined or expected so you think it could be better.
On the other hand
I did my best means you could perform your very best because nothing was conspiring against you.
nothing was conspiring against you I meant that you were in a perfect moment, inspired, healthy and psychologically prepared to do your very best.
I am not a native English speaker. In English, there are many expressions that you use to add emphasis to superlatives. For example:
She is the most beautiful woman.
She is the most beautiful woman I have ever seen.
She is the most beautiful woman I have ever seen on the face of the earth.
Which of the three do you think has the strongest emphasis that there could be?
Usually, the relative clause that follows any superlative is used for emphasis. I think "I did the best I could" adds more emphasis. But it is less emphatic than
I did the best I could possibly do in my entire life.
This is a very interesting question, and I was intrigued to read the answers given. My impression of the phrases is slightly different, so I thought I would share my insights. (I am, by the way, a native English speaker from the western United States.)
I did my best - Self affirmation, or reassurance that one has given something their best effort and can feel good about that effort. In essence, one is saying, "I feel good about my efforts."
I did the best I could - Defensive statement, attempting to convince others that one did the best that could have been expected of them by anyone judging the situation. In essence, one is saying, "You couldn't expect more of me."
Despite my personal impression of these phrases, I could see someone using either phrase to express either meaning. I could even see myself exchanging these terms with their meanings in certain circumstances, so clearly they're not mutually exclusive.