I’ve reread the entire paper twice in the last several days because I admire what Carroll says AND how he says it. One paragraph has always jumped out at me. Read it for yourself below, then I’ll explain why.
Back when I stopped being Christian in the ’70’s, I still retained this slight suspicion that reality still contained some supernatural aspect. Years later, as I tried to assemble a somewhat accurate picture of reality, I backed in to the idea that the universe that I can observe consists of space and time (later, “spacetime”), matter and energy, and exhibits behaviors that could be observed, and could help me to validate my mental picture of it. Naturally, I tried to imagine where supernatural things might fit into this picture.
The essence of materialism is to model the world as a formal system, which is both unambiguous and complete as a description of reality. A materialist model may be said to consist of four elements. First, we model the world as some formal (mathematical) structure. (General relativity describes the world as a curved manifold with a Lorentzian metric, while quantum mechanics describes the world as a state in some Hilbert space. As a more trivial example, we could imagine a universe which consisted of nothing other that an infinitely long list of ”bits” taking on the values 0 or 1.) Second, this structure exhibits patterns (the ”laws of nature”), so that the amount of information needed to express the world is dramatically less than the structure would in principle allow. (In a world described by a string of bits, we might for example find that the bits were an infinitely repeated series of a single one followed by two zeroes: 100100100100…) Third, we need boundary conditions which specify the specific realization of the pattern. (The first bit in our list is a one.) Note that the distinction between the patterns and their boundary conditions is not perfectly well-defined; this is an issue which becomes relevant in cosmology, and we’ll discuss it more later. Finally, we need a way to relate this formal system to the world we see: an ”interpretation.”
I once thought it obvious that there could be only a few ways to reconcile the supernatural with the natural. 1) the supernatural is the framework upon which the other things rest. 2) we exist wholly within some supernatural environment. 3) the supernatural is separate, but somehow meaningful in ways that are unclear. 4) we - and the universe - ARE wholly supernatural, and we just don’t recognize it (Or refuse to acknowledge it). Clearly some of these ideas overlap, but that’s what I can recall.
Once I had my framework for thinking about the universe to validate my (4) suspicions on what the supernatural might be, ideas of supernatural agency in the universe started to drop by the wayside. By the start of the new millenium, this informal process was complete - I was functionally - if not consciously - atheist. So what’s that have to do with Carroll’s paper?
When I read Why (Almost All) Cosmologists Are Atheists a few years ago, it validated the approach I had taken to arrive at a naturalistic world view. The specific paragraph that I quote above, although more eloquent and more complete than I was thinking, essentially turns into this for laypeople like me:
- describe what entities there are in your system
- describe how they behave
- define the extent of the system
- compare your model to reality and articulate it for review
Easy as pie!