partial conditionals

[ewelina]

I have heard people say:

"If you will excuse me please, I will leave you for a moment and visit the restroom."
and from the Collins Cobuild Dictionary:
"I wonder if you would be kind enough to reach for my umbrella"
or:
"If you will just sign here, we will arange the money transfer this minute"

which stands in contradiction to what I was taught at school about conditionals. Does politeness justify this kind of sentence? What kind of situation is it used in?

Please advise,
Ewelina

[Tdol]

They can be used to be polite, when trying to negotiate. They balance the tenses in the two halves to suggest equality of concession.