Fetching details from the dictionary...

but then; although; though
reasonable; natural; just
もっとも彼の言うことも一理ある。
Although what he says has a point.
もっともな意見だと私も思いますよ。
I also think it's a reasonable opinion.
もっとも、それは私の考えに過ぎない。
Although, that's just my opinion.