Continuous versus Discrete
The environment, as people perceive it, is essentially continuous, and we are conscious of moving and interacting in the three dimensions of space, along with that of time. The same is true of many important derived variables such as mass, liquid volume, light intensity, and so on. In some cases the apparent continuity is known to break down at the atomic level, as for example a volume of liquid consists of discrete molecules, and light is made up of photons, and it is possible that other variables such as length and time may be quantised at some level. Nevertheless, as far as direct perception is concerned, everything seems to conform to old-style elementary physics in which variables are treated as continuous. It is reasonable to suppose that evolution, including that of intellect, occurred in an environment that is either essentially continuous or has been made to appear so by evolutionary choice of the means of experiencing it.