What does the "も” mean in "ーてもいいですか”


When asking for permission to do something in Japanese, a common form is the
te form verb + もいいですか . My question is does the te form "nounify" or
nominalize the verb and what grammatical purpose does the も serve in this
construction.




も means "also".

As for the difference between 家に来ていいよ and 家に来てもいいよ, 家に来ていいよ feels like the
speaker knows that the listener wants to go to his house, 家に来てもいいよ feels like
the speaker doesn't know if the listener wants to go to his house.

As for the difference between 家に行っていいですか？ and 家に行ってもいいですか？, they have less
difference than 家に来ていいよ and 家に来てもいいよ.

But the former one feels like the speaker requests the permission more
strongly or the speaker knows that the listener may permit because he always
goes there.

The latter one feels like the speaker doesn't know if he would permit.

