An interesting side discussion came up on a similar forum with some help from a member of this one. If you are a magician, you hope that anyone who witnessed your illusion will be able to describe the miraculous thing they saw, preferably without knowing how the illusion was actually achieved, or even how to accomplish a similar illusion themselves. If you are a scientist, you hope (or perhaps you should) that anyone who makes use of your theory will not only be able to apply it successfully to other situations, but also gain a better understanding of the underlying principles and if possible, the causes of the behavior your theory explains. Despite this ideal, it is a fact that quite a bit of basic science and math is descriptive only, and in exactly the same way that a magician's audience would applaud. For example, Newton's Law of Gravitation: Fg=(GmM)/r^2. A knowledge of this theory allows us to predict most planetary orbits, launch satellites into orbit, etc. However, an assumption of NLG is that objects fall IN THE DIRECTION OF THE CENTER OF THE EARTH. How would a rock or other object "know" where the center of the Earth actually is? A falling rock can find the direction in which to fall even in the dark, and does so without any instruments or senses. How does it do that? For Newton, it was a "divine hand" that gave the falling object its direction. So this is a good example of a theory that is descriptive only. No cause for gravity is either assumed nor predicted, nor, by the way, is it likely that such a cause would reside in the matter of which the rock or the Earth is made of. Do you see now how this is similar to a magician's illusion? A very good one it still is, too. When a mathematician tells us that objects in free fall follow a path determined by a vector field in curved space-time, it may be true that the predictions of such a theory are much more accurate than Newton's law of gravitation. But that mathematical form, a vector field, likewise obtains its direction at each point in space-time from the mathematician's mind, not because the underlying cause is known. Like the falling stone, this theory is likewise a descriptive one. No cause relating to its direction, other than that given by a theory which requires us to measure forces and ascribe directions to it, is either asserted or assumed. Similar constructs include most of Maxwell's equations, Schroedinger's Wave Equation, and virtually all of quantum mechanics. Is this really science, or does it share with illusion only a description (observation) without revealing a real cause? Debate question: Do scientific theories or mathematical descriptions need to suggest or reveal actual causes of the effects they observe / describe in order to be complete?