Westerhoff opens his essay with this:
What do we actually mean by reality? A straightforward answer is that it means everything that appears to our five senses - everything that we can see, smell, touch and so forth. Yet this answer ignores such problematic entities as electrons, the recession and the number 5, which we cannot sense but which are very real. It also ignores phantom limbs and illusory smells. Both can appear vividly real, but we would like to say that these are not part of reality.Later in the piece Westerhoff adds:
There are two definitions of reality that are much more successful. The first equates reality with a world without us, a world untouched by human desires and intentions. By this definition, a lot of things we usually regard as real - languages, wars, the financial crisis - are nothing of the sort. Still, it is the most solid one so far because it removes human subjectivity from the picture.Well, this is interesting. In the paragraph op cit. Westerhoff suggests that human subjectivity shouldn't be part of our picture of reality, but what if what stands at the "bottom of the chain of dependence" is mind rather than anything material? What if, as physicist Sir James Jeans once observed, the universe is more like a grand idea than a grand machine? What if mind is the fundamental reality and matter is just an illusion we experience because we're the size and sort of beings we are?
The second equates reality with the most fundamental things that everything else depends on. In the material world, molecules depend on their constituent atoms, atoms on electrons and a nucleus, which in turn depends on protons and neutrons, and so on. In this hierarchy, every level depends on the one below it, so we might define reality as made up of whatever entities stand at the bottom of the chain of dependence, and thus depend on nothing else.
I'm not saying that matter is just an illusion, but when we reduce matter down to the "entities that stand at the bottom of the chain of dependence" we find that they themselves are immaterial. They're simply energy (whatever that is). If atoms, the basis of all material stuff, are reducible to just energy then in what sense are atoms real, and, a forteriori, in what sense is matter real?
There are stirrings in both physics and philosophy that suggest that at least some of the practitioners in each of these fields are growing increasingly disenchanted with the 19th century view that reality is fundamentally material. Indeed, I suspect that the only reason that more of them are not abandoning materialism altogether is that the view that the world is at bottom a product of mind has too many disconcerting theological implications.