the.com/argumentation

means The process of giving organized reasons and evidence to support a claim or persuade someone else it's true.

from Traces back to the Latin 'argumentum' (proof, evidence, basis for a claim), itself from 'arguere' — to make clear, to prove, or to accuse. That root 'arguere' is possibly related to a deeper Indo-European base meaning 'to shine' or 'make visible' — the idea being that a good argument doesn't just assert, it illuminates. The '-ation' suffix just nails on the sense of 'the ongoing act of' — so argumentation is, quite literally, the act of making your case shine.