On Fri, Feb 02 2018, Peter Humphrey wrote: > I agree. You haven't consulted Fowler though, I see. (Drat! Where's my copy > when I need it?) He says the difference is whether we have a defining > clause. If what follows actually defines the subject of the sentence, use > "that". Otherwise it's "which".
The terminology I was taught is that "which" introduces a nonrestrictive clause set off in commas "that" introduces a restrictive clause. "The ice cream that is in the fridge is cold" restricts the assertion of coldness to the ice cream in the fridge as opposed to some other ice cream. "The ice cream, which is in the fridge, is cold" asserts two points. The ice cream is cold. The ice cream is in the fridge. allan
