'Conclude' is Latin for 'shut completely' — a conclusion is where the argument closes.
To bring to an end; to arrive at a judgment or decision by reasoning; to reach agreement on; to settle or arrange finally.
From Latin 'conclūdere' (to shut up, to close, to enclose, to end), composed of 'con-' (together, completely) and 'claudere' (to shut, to close). The PIE root is *klāu- (hook, peg). The Latin prefix 'con-' here intensifies the root, giving the sense of 'shutting completely' or 'closing up entirely.' The logical sense — to
In formal logic, a 'conclusion' is the final proposition that follows necessarily from the premises — the point where the argument closes shut and nothing more can be said. This is the original Latin metaphor perfectly preserved: 'conclūdere' meant to close something so completely that it was sealed.