Noun + はいざ知らず

[I don't know about X, but... / Regardless of X]

Connection: Noun + はいざ知らず

Usage: Used to set aside one case as unknown or irrelevant, then state that the current or actual situation is different. Similar to はともかく but more literary. "I can't speak for X, but Y is certainly the case."

Examples:

昔はいざ知らず、今の時代にそんな考えは通用しない。(I don't know about the past, but such thinking doesn't work in today's era.)

他の人はいざ知らず、私は絶対に賛成できない。(I can't speak for others, but I absolutely cannot agree.)

プロはいざ知らず、素人にこの仕事は無理だ。(I can't speak for professionals, but this job is impossible for amateurs.)