whether or if?

An indirect question may begin with either word. Whether is particularly common when or not is added:

He wanted to know if/whether I had been there.
I don't know if/whether he speaks Portuguese or not.

Cheers
CB

Hi,

I see this situation as very similar to the question of whether/if I should insure my home against fire.

With regard to this specific sentence, the/a question of is an idiomatic phrase that does not work with 'if'. Say the question of whether.

Or, you could say the question of home insurance against fire

The combination of if is not used, nor the combination of any preposition followed by if.

CJ

CalifJimThe combination of if is not used, nor the combination of any preposition followed by if.

CJ

One has to be careful saying that. It is used in situations like this one:

"they can be disposed of if they become..."

And the "of if" combination is used in place of "of whether" by quite a few speakers

Good examples. There are obviously situations where of if can be used. The "rule" needs to be refined.
So what is the correct phrasing of the rule, to take these cases into account? Something like this?

of if is not used except:
of if is OK if contrasted with of when.
of if is OK if the of completes one clause and the if b