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Sometimes, people tend to use metaphors from arithmetics to refer to something
in ordinary life. For example, to mention some claims or preferences common
among people, the expression `最大公約数` 'greatest common measure' is used even
though it is not about numbers. I kind of understand that because there is no
immediate counterpart that expresses the corresponding concept for non-
numbers. But I don't understand why people say `未知数` 'unknown variable' for
some non-number that is unknown. There is a word `未知` 'unknown' that is
related to and is simpler. Why do people say things like `これからの情勢は未知数だ`
instead of saying `これからの情勢は未知だ`?
CC BY-SA 3.0
2011-12-20T22:29:41.370
4034
2011-12-21T07:19:50.227
question
metaphor
Why do people say 未知数 when it is not a number?
This is not necessarily an idiomatic structure. English uses the exact phrase
when talking about unknowns.

"Candidate X is an unknown variable so anything can happen once he/she enters
the race."

Mathematical terms tend to be constants (yet another mathematical term) and
many are actually co-opted from real world use to talk about mathematics.
Alphabets are similarly used such as "crossing your t's and dotting your i's"
to indicate finishing up properly, and "teaching him all the steps from A to
Z", or referring to God as "the Alpha and the Omega" to indicate all
encompassing. In Japanese, such things are "ア から ン".

The point is that, these terms are rather similes rather than idiomatic. They
tend to be directly comparative rather than obliquely obscure.
CC BY-SA 3.0
2011-12-21T07:12:30.113
4038
2011-12-21T07:19:50.227
2011-12-21T07:19:50.227
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answer