careful vs. careless

[spoon]

Hello again

This is other question. I've appreciated your help.

Could you please look at these sentences?

(a) John is careful to do so.
(b) John is careless to do so.

Both are correct.

(a) *It is careful of John to do so.
(b) It is careless of John to do so.

My grammar book says (a) is not correct. Could you please explain this to me?

Many thanks.

[Tdol]

We'd use something like 'John takes care to do it', meaning that he is careful about ensuring that he does it. The 'it is careful...' idea doesn't work. It's not that it's ungrammatical, because the logic is fine; it's more a question of usage and 'it is careful of him' is not a natural pattern. Simply because something's the opposite in meaning, it doesn't necessarily follow that it can behave in exactly the same way.

[spoon]

Thanks tdol. Your answers are always fascinating!

[Tdol]

You're welcome, Spoon.