Alex Rosenberg, the author of The Atheist’s Guide to Reality, argues that “we should embrace physics as the whole truth about reality”. On the face of it, that’s a remarkable statement open to obvious challenges.
Rosenberg, however, acknowledges that parts of physics are relatively speculative, unsettled or even inconsistent. It’s the solidly-confirmed part of physics that he’s talking about, the part of physics that is “finished” and “explains almost everything in the universe – including us”. What he’s really claiming, therefore, is that settled physics is the whole truth about reality.
But is settled physics actually true? Philosophers disagree about what science is, what truth is and, not surprisingly, how close science gets to the truth, but I agree with Rosenberg that settled physics seems to be true. The predictions of special relativity, for example, appear to be 100% correct. (This isn’t to deny that some settled physics might become unsettled one day.) As evidence of the reliability of physics, Rosenberg points out how precise some predictions are: “quantum electrodynamics predicts the mass and charge of subatomic particles to 12 decimal places”. Those predictions are “true” in any reasonable sense of the word, even if physicists eventually refine their predictions to even more decimal places.
Some philosophers and scientists don’t accept Rosenberg’s “scientific realist” view, however. They think science is merely a tool that allows us to get things done. Questions like whether electrons or other theoretical entities really exist as physics describes them are put aside, since they’re viewed as unanswerable and irrelevant. Personally, I think physics allows us to get things done because it’s true, and furthermore it’s true in the sense that the objects and events physics describes are real, whether they’re observable or not. I believe that’s Rosenberg’s opinion too.
The second, more interesting challenge to Rosenberg’s view of physics concerns his claim that settled physics is the “whole” truth about reality. Clearly, there are mathematical and logical truths, which aren’t part of physics, but I take Rosenberg to be referring to truths about the universe and its contents, i.e. “real” stuff.
Nevertheless, if physics isn’t finished, it can’t be the “whole” truth. There must be some physical truths yet to be discovered (for example, what’s the story on dark matter and dark energy, two big things we know little about?). So Rosenberg’s claim that we should embrace settled physics as the whole truth about reality should really be understood as “settled physics is the only truth about reality we currently have”.
Two obvious questions remain, however. Do we discover the truth from sciences other than physics? And do we learn anything true about the world even when we aren’t doing science?
Well, most people would agree that chemistry, for example, is a science that gets at the truth if any science does. Rosenberg clearly knows about chemistry, so why would he deny that chemistry is as valid as physics? The answer is that he thinks physics has shown there is nothing in the universe except fermions (e.g. quarks) and bosons (e.g. photons). From the idea that fermions and bosons are the only things that really exist, he concludes that all of reality can be explained in terms of those sub-atomic particles. After all, everything in the universe involves elementary particles being somewhere or doing something. Since physics is the science that tells us all about elementary particles and what they do, it’s the fundamental science. Using physics, therefore, we can explain chemistry, which we can then use to explain biology. Another way of saying this is that biology is reducible to chemistry and chemistry is reducible to physics. Knowledge of physics is the only knowledge that counts, because “the physical facts fix all the facts”, including chemical and biological facts.
The big problem with this point of view, aside from the difficulty in actually carrying out such reductions (replacing chemistry with physics, for example) is that fermions and bosons do such interesting things when they interact or are arranged in certain ways. Put some together and you have atoms; put some atoms together and you have molecules; put some of them together and you have cells. Once low-level particles are arranged as, for example, clouds or baseballs or trees, patterns or regularities in the behavior of these higher-level entities emerge. There are new facts to be learned.
If the universe were merely a collection of sub-atomic particles randomly scattered about, there wouldn’t be any chemical or biological facts for chemists and biologists to discover. But the particles in our universe aren’t randomly scattered. They’ve clumped together in various ways. Acquiring knowledge about these clumps (of which you and I are examples) is what chemists, biologists and other scientists (geologists, astronomers, psychologists, etc.) do. Rosenberg knows this, of course, but for some reason downplays it, choosing to focus on physics as the sine qua non of science. In virtue of its power and generality, physics should be embraced as the most fundamental science, but it clearly isn’t the only science worth embracing.
The other question raised by Rosenberg’s scientism (or physics-ism) is whether we can add to our knowledge when we aren’t doing science at all. Rosenberg doesn’t seem to think so. Although science is built on observation, he is extremely skeptical about what can be learned by simply looking and listening. He also seriously mistrusts introspection. More on this later.
Next: The 2nd Law of Thermodynamics and us.