"我明白了道理"在英文中可以译作"I understand the reasoning/principle."

"Reasoning"是"推理"的意思，"principle"是"原则"的意思。因此，"I understand the reasoning/principle"可以用来表示"我明白了道理"的意思。

例句：

I understand the reasoning behind your decision. (我明白你做决定的原因。)
I understand the principle of supply and demand. (我明白供求原理。)

希望这对你有帮助！