RULES OF CORRESPONDENCE work two ways. They allow us to pass from Nature to the field of constructs, and when used in reverse they provide us with expectations. In this latter mode they furnish what Lewis1 has aptly called "terminating judgments." The reversals are, however, in need of some analysis, for they can be accomplished in trivial and in nontrivial fashion.
A trivial reversal of a rule of correspondence occurs when the path which led originally to the formation of a construct is retraced. Seeing a tree is an act which, though integral in a psychological sense, nevertheless involves the heterogeneous elements of immediate awareness and construction; it serves to set up the external object, tree. If, having seen a tree and then gazed elsewhere, I turn back in the former direction and expect to see the tree, that expectation is a trivial reversal of a rule of correspondence. Another is the judgment that the sun will rise tomorrow, or that sweet coffee contains sugar, or that an electrical discharge in mercury vapor is green.
But suppose we hear the sound from a bell and, remembering simple physics, assume it to be a vibratory disturbance in the surrounding air. Very little reflection then tells us that, if there were no air, the vibrations could not exist and the bell could not be heard. Hence, having become curious, we place the bell under a jar, evacuate it while the bell is ringing, and find the sound slowly dying away.
In "predicting" this we went through the following little exercise: From the sound sensed in Nature we proceeded by a____________________