This isn't that big a deal I just thought I would see what others think. The UNICOM Level 2 grammar book l have lists this 黒白を争う with a reading of しろくろをあらそう. I showed it to a Japanese teacher and she looked it up somewhere and said that was correct. Then in Kenkyusha it is listed under こくびゃく which would make a lot more sense unless the whole point of the idiom is to argue over which reading of the idiom is correct. If that is the case then this has to be one of the coolest idioms I have seen so far. Anyone else know more?

I'm not familiar with that idiom, but generally, the reading for 白黒 is しろくろ.

You probably already noticed that 黒白 alone is also listed in Kenyshusha under [kana]kuroshiro[/kana] (with a pointer to the [kana]shirokuro[/kana] entry). hmm It may very well be a clever idiom! But it looks like the [kana]kokubyaku[/kana] reading applies in other phrases too. It's not in my idiom book. Japanese google?

[Edit typo こ to く]

That is why I am curious. The idiom's meaning is "to argue about which is correct". So I wonder if by switching the kanji around but leaving the reading　as しろくろ, the idiom is its own example. People would, after all, correct someone reading 黒白 as 白黒. The other option is that the UNICOM book and the teacher that looked it up were both wrong. I found several Japanese websites supporting the Kenkyusha reading of こくびゃく in this idiom. I would have normally tossed it up to a typo except for the fact that the teacher backed up the funky reading.

The 黒白 reading of こくびゃく is also presented in RTK2, page 78.

My question is not about how to read しろくろ or こくびゃく I know both of those. My question is about the idiom. Are you supposed to read it wrong in the idiom?