Fourth chapter - Theoretical conclusion established on the basis of all the observations contained in the first part

Summary

Scales, intended by civil law to be a standard of measure in trade, may be shown to be inaccurate if the wares and the weights are made to change pans. The bias of the scales of understanding is revealed by exactly the same stratagem, and in philosophical judgements, too, it would not be possible, unless one adopted this stratagem, to arrive at a unanimous result by comparing the different weighings. I have purified my soul of prejudices; I have eradicated every blind attachment which may have insinuated itself into my soul in a surreptitious manner with a view to securing an entry for a great deal of bogus knowledge. Now, whether or not it confirms or cancels my previous judgements, whether it determines me or leaves me undecided, nothing is important or venerable for me except that which, having followed the path of honesty, occupies its place in a tranquil mind open to any argument. Whenever I encounter something which instructs me, I appropriate it. The judgement of the opponent who refutes my arguments becomes my own judgement, once I have put it on the scales and weighed it first of all against the scale of self-love, and men, having transferred it to that scale, against my own alleged reasons, and found it to be of superior quality. I formerly used to regard the human understanding in general merely from the point of view of my own understanding. Now I put myself in the position of someone else's reason, which is independent of myself and external to me, and regard my judgements, along with their most secret causes, from the point of view of other people. The comparison of the two observations yields, it is true, pronounced parallaxes, but it is also the only method for preventing optical deception, and the only means of placing the concepts in the true positions which they occupy relatively to the cognitive faculty of human nature.