Tutoring English, grammar inevitably arises. The tutor mentions a use of which he’s long considered.
Decades ago I read a humorous article I really liked that included something like this:
He didn’t like that dish. Which is why he always ordered it.
Although I really liked that construction, I didn’t believe I’d get away with it in an English assignment. Therefore, I never used it myself. Still, I wondered what, technically, would be wrong with it.
Perhaps today I have found the answer: Which is a relative pronoun, meaning it refers to a noun in the central idea of the same sentence it appears.
In the quote above, which refers to the idea stated in the previous sentence: He didn’t like that dish. To be used properly, which must represent a noun in its same sentence, perhaps like so:
He didn’t like that dish, which is why he always ordered it.
Hodges, Horner, et al. Harbrace Handbook for Canadians, 6th ed. Scarborough: Nelson Education, 2003.
Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.