I am trying to figure out what additional semantic information "both" carries when used in a sentence. Does it differ from "and"?
Take the following sentences:
Alice and Bob both ate lunch.
Alice and Bob ate lunch.
What extra is gained by the "both" in the first sentence? Do either of the sentences give a stronger or weaker implication that the activity was performed together or separately? I've been overthinking it, so I don't know what my intuition tells me anymore. My initial thought was perhaps that using "both" added a stronger implication that the activity was shared between the two rather than separate events. If the word "together" is added to the end of either sentence, I feel that it feels a bit superfluous on the first, with "both" (yet not a questionable or starred sentence), and much more natural with the second, as in "Alice and Bob ate lunch together".
Looking at a dictionary entry, it would imply that "both" is used for emphasis, but gives the examples with "both" being in an initial position, which I feel automatically gives emphasis - "Both Alice and Bob ate lunch" seems to actually have a whole different feel to it, and to me would be used more to correct an incorrect assumption. "I thought only Bob was there..." "No, both Alice AND Bob ate lunch..."