Typically the superlative expressed with most or –est requires a definite article because the semantics of the superlative requires a unique element. So in a context where there are two equally tall people in the room, it's infelicitous to say (1)
- Arthur is the tallest person in the room.
This is typically true of how the definite article works in English independent of the superlative. The definite article usually picks out a unique individual in the context. For example, the following is also an infelicitous use of the definite. (The # symbol is used to mean "inappropriate for the context".)
- Arthur and Bob came into the room. #The man sat down.
So the use of the definite in the superlative follows from the fact that there is a unique individual who satisfies the description.
It's not true, however, that the superlative requires a definite article. For example, suppose we are inquiring about the heights of the players on a basketball team. It's perfectly reasonable to say (3):
- Does this team have a tallest player?
Here, uniqueness is what's being questioned, and so the indefinite article is used, and the definite is impossible. Similarly, if we were evaluating all the teams in a league, we could felicitously say something like 4.
- Every team except two has a tallest player.
In these cases the uniqueness requirement of the superlative is being evaluated relative to each team, so these noun phrases could be paraphrased as "a player who is the tallest one on that team".
The preference of the definite article with adjectives like right and wrong is again due to the fact that there is a presupposition that there is a unique right or wrong answer in the context, but this isn't really built into the meaning of these adjectives. Any time this expectation is not met, the indefinite article will be able to be used:
- For this question both Sara and Lisa gave a right/wrong answer.