Your assumption presupposes that we all agree with the plan, but that's not the case.

presupposes 是动词 presuppose 的第三人称单数形式。presuppose 由前缀 pre-（表示"预先"）和 suppose（假设）组成，意思是"预先假设、以...为前提"。这个词强调在提出某个观点或行动之前，已经默认接受了某些前提条件。