"it's truly vital that he or she becomes/become familiar with the reasons"?

Question

Please have a look at sentence below:

Before one votes on the proposition, it's truly vital that he or she becomes/become familiar with the reasons for voting both for the proposition and against the proposition.

Does it have any grammar issue?

My book says, "become familiar", "proposal". Do you agree with the book?

Answer 1

There's nothing wrong with calling it a "proposition". Ballot issues (in AmE) can be called "propositions". However, the sentence seems to be speaking of only one of them, so I would suggest consistent use of the singular "proposition".

As for "become", the book is correct—but this is not the conjugated third-person-plural "become", it is the subjunctive "become".

• (important that) {whoever} become

The only other thing that is syntactically odd is the placement of "both". One needs to be aware of reasons for voting for, or against, the proposition, but most localities won't let you VOTE "both for and against" it, no matter how good your reasons!

• ...the reasons, both for voting for the proposition and for voting against {it/the proposition}.