"What was best" vs "what was the best"?

Question

Do both have the same meaning? Or they are subtly different?

Example sentence:

What was (the) best? To go left or right, up or down?

In an answer on englishforums.com it says that both are exactly the same. But I wonder if that's really the case.

Answer 1

In your context, the best relates to {something}, whereas best relates to a course of action.

Plastic, wood, or metal container? What was the best ^choice for this purpose?

Plastic, wood, or metal container? What was best ^{to choose} for this purpose?

Either is acceptable, and the practical meaning is the same, but their referents, implicit not explicit, are different.

Answer 2

In many sentences it will not matter if "best" or "the best" is used. To my ear, "best" on its own tends to sound better, but that may be due to the way my family spoke as I was growing up. However, sometimes grammar demands one or the other.

What was the best present you received?

This just doesn't work without the "the".

It will be best if we just forget about it.

Opposite of the first example. Adding "the" doesn't work, although one could substitute the prepositional phrase, "for the best". The phrase requires "the".

Answer 3

The confusion arises because the word best can be used as any of several different parts of speech.

On the linked page, best is used as an adverb, modifying the verb knew. In that context, the phrase the best can also be used as if it were an adverb. The meaning is approximately the same in that case.

In the following sentence, however, best is an adjective: "What was best?"

If we insert the word the, we get a noun phrase, the best. You could certainly declare that after comparing a number of things, you found that a particular one of those things was the best. That is to say, it was better than any of the others. So if you knew someone who had tried going up, going down, going left, and going right, you could ask them for their evaluation of the relative benefits of each of those actions: "Which was the best?" (Note that I would say which rather than what.)

Assuming that the passage in the question is about the thinking of someone who is faced with choosing a course of action to take, not evaluating the outcome of an action already taken, I would use best as an adjective.

What was best? To go left or right, up or down?