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(a) principle; (a) reason; (a) point; some truth
彼の意見にも一理あると思う。
I think his opinion has some truth to it.
反対派の主張にも一理はある。
The opposition s claim also has a point.
一理あるが、全面的には賛成できない。
There is some truth to it, but I cannot fully agree.