I am 63 with a Ph.D in neuroscience and had laboured under the misapprehension that the were two versions—sence and sense, until very recently. The physiological meaning sense of course I always got right, as befits my profession. When I wrote something like “common sence” and someone corrected me, I just just assumed that that must be a grammatical exception, but could never figure out why or when to use the other presumed version. Once I learnt that (apart from a river and a couple of minor instances) there is only one way to spell sense, life was so much simpler. One wonders why myself and the originator of this thread made the same error, which must have occurred early in our educational histories.