 Now set the preceding problem aside. There is still another developed in Fodor (1984). Suppose that “X” does mean dog under conditions of good lighting, lack of serious occlusions, etc. Do not merely suppose that “X” is caused by dogs under conditions of good light, lack of serious occlusions, etc.; grant that “X” really does mean dog under these conditions. Even then, why does “X”, the firing of the neuronal circuit, still mean dog, when those conditions do not hold? Why does “X” still mean dog under, say, degraded lighting conditions? After all, we could abide by another apparently true conditional regarding these other conditions, namely, if the lighting conditions were not so good, there were no serious occlusions, etc., then the neuronal circuit’s firing would mean dog or fox. Even if “X” means X under one set of conditions C1, why doesn’t “X” mean Y under a different set of conditions C2? It looks as though one could say that C1 provides normal conditions under which “X” means X and C2 provides normal conditions under which “X” means Y. We need some non-semantic notions to enable us to fix on one interpretation, rather than the other. At this point, one might look to a notion of functions to solve these  problems.[7]