理論は理にかなっていたけれども、彼は納得しなかった。
tbd
Although the arguments were rational, he was not convinced.
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納得， なっとく
1. consent, agreement, acceptance
2. understanding, satisfaction (e.g. with an explanation), being convinced
理解、满意(如对解释)、信服；想通了、同意、接受
は
1. indicates sentence topic
2. indicates contrast with another option (stated or unstated)
3. adds emphasis
指示句子的主题；表示与另一选项（无论是否明确提及）形成对比；表示强调