"The general notions about human understanding… which are illustrated by discoveries in atomic physics are not in the nature of things wholly unfamiliar, wholly unheard of, or new. Even in our own culture they have a history, and in Buddhist and Hindu thought a more considerable and central place. What we shall find is an exemplification, an encouragement, and a refinement of old wisdom."
Julius Robert Oppenheimer.

The question "how many angels can dance on the head of a pin?" is often, nowadays, used as a metaphor for medieval nonsense. However it is, in fact, a medieval formulation of what is today called the mind-body problem: what is the relationship between matter and mind? and, does mind exist at all?
In the medieval world the movement of the planets around the Earth was understood in quasi-supernatural terms. Angels, semi-divine beings, were responsible for this phenomenon. And explanations for a great deal of natural phenomena had similar explanations. Aristotle's physics, together with a Christian mythos, was the basis for medieval European man's understanding of observed phenomena. A modern man might experience the same phenomena as the medieval person but his understanding of these observations would be quite different.
The philosopher of mind Thomas Nagel posed the question: "what is it like to be a bat?". As bats negotiate their surroundings using echolocation, a sense that does not exist in humans, their subjective world is unknowable to us. It would be impossible for a human to imagine how the world would be experienced by a bat. A dog has a sense of smell that is not simply more keen than that of a human; the canine sense of smell will furnish more complex forms of information to a dog than is possible for the human sense. If a fly has any awareness - a possibility - it might take the form of a small number of either/or possibilities: flying/not-flying, eating/not-eating etc. Therefore the world of a cat, for example, is not just simpler than that of a human. While the cat certainly has less intelligence than a human, but more than a frog, its world is also qualitatively different.
The universe, said a scientist, is not just more complex than we imagine but more complex than we can imagine. Our experience of reality is limited by the level of analysis available to the human mind/brain apparatus, and there is a qualitative aspect to the available level of analysis as with any species. A species from a distant planet with a brain much larger and more complex than a humans would have the capacity to engage with reality in much more profound and complex ways than we do and understand aspects of the universe, truths, that are beyond our understanding.
Some higher animals share with humans, although to a very limited degree, the capacity to form theories. We higher animals do not just experience reality and perform actions based on these experiences, we understand these experiences in an intellectual manner before then acting. Human cultures, in all their forms, are a product of this extra intellectual dimension. For example when medieval man experienced the motion of the heavenly bodies he created the theoretical understanding of these phenomena involving angels. Many people in western society today believe that the motion of the planets as well as the phenomenon of objects falling to the ground near the Earth, two entirely different events in terms of Aristotelian physics, are as a result of the action of a phenomenon called 'gravity'. This is untrue. Gravity is an invention of the human mind. It is, of course, a very good invention. It is a rigorously defined mathematical concept, a tool, which can be used to predict the behaviour of physical objects in a large range of situations, but not in all situations. Any mathematician will tell of formulae that will produce the right answer but for the wrong reason. Gravity is such a theoretical construct. The best stab at what is actually involved here is as follows: we exist in a four dimensional space-time continuum, even if the forces of evolution have produced in us only the capacity to subjectively experience three dimensional space and a separate phenomenon of time. Just as liquids will find their own level in three dimensional space, (water will flow to the lowest possible level via the 'easiest' path), a massive object will negotiate curves in space-time in an analogous manner. Put simply, Einstein's General Theory of Relativity has disproved the existence of gravity.
And angels? As an explanation for the behaviour of celestial bodies the action of angels is obsolete. However….. Modern quantum physics recognises that mind, a non-material mind, is indispensable to any understanding of nuclear physics. This does not cease to be the case whenever we humans are not actually actively engaged in nuclear physics. Most, but not all, physicists hold that mind must exist. And it is an empirically established fact that mind emerges from, or, more accurately, is intimately associated with, the brain. Angels, it seems, using the now archaic terminology, continue to dance on, well, physical objects.

Brendan Burke MA(Phil)
Cork Unitarian Church
26 August 2008