～かというと

かというと puts a question into words and then answers it: "if you ask why…", "if you ask whether…". A verb or an い-adjective comes before it in the plain form, and a noun or a な-adjective takes it directly, with no だ.

With なぜ or どうして in front, it sets up a reason, and the answer ends in からだ or からです.

The question promises a reason, so leaving off からだ makes the answer sound cut short.

• × なぜ遅刻したかというと、電車が止まった → 電車が止まったからだ
• × なぜ人気だかというと → なぜ人気かというと

Doubting an assumption

Without a question word, かというと raises something the listener might take for granted – that it's easy, that everyone agrees – and the second half says it isn't quite so. The usual answers are そうでもない, そうとはかぎらない限らない, or a more careful verdict.

Usage notes

These go beyond setting up a reason or a doubt.

どちらかというと

The set phrase どちらかというと means "if anything", "if I had to choose", and gives a mild preference.

かといえば