Relation of proportions.
My success arose from the necessity of teaching logic to neurologists, psychiatrists, and psychologists. In his letter to a German princess, Euler used circles on the page to convey inclusions and intersections of classes. This works for three classes. Venn, concerned with four or five, invented his famous diagrams in which closed curves must each bisect all of the areas produced by previous closed curves. This goes well, even for five, by Venn's trick; six is tough; seven, well-nigh unintelligible, even when one finds out how to do it. Oliver Selfridge and Marvin Minsky (also of Lincoln Laboratory), at my behest, invented a method of construction that can be continued to infinity and remain transparent at a glance. So they
formed a simple set of icons wherewith to inspect their contents to the limit of our finite intuitions. The calculus of relations degenerates into the calculus of classes if one is interested only in the one relation of inclusion in classes. This, in turn, degenerates into the calculus of propositions if one is interested only in the class of true, or else false, propositions, or statements in the realistic case. Now this calculus can always be reduced to the relations of propositions by pairs. Thanks to Wittgenstein we habitually handled these relations as truth tables to compare their logical values. (EM 15)
This page was last updated on July 29, 1996, by Rob Sable.