What to do

We seem to have two choices:

1.

Make $\llbracket$ John and Mary $\rrbracket$ a set and give that set as an argument to the verb.

2.

Make $\llbracket$ and $\rrbracket$ be a function that gives its first two arguments to the function that is its third argument in the appropriate way.

Basically, we can put the duty of interpretation onto either the verb or the conjunction.