La Repubblica recently published an extract of a forthcoming translation of The Grand Design by Stephen Hawking and Leonard Mlodinow, with a subtitle from a passage in the book: “Philosophy is dead, physicists alone can explain the cosmos.” The death of philosophy has been announced a number of times, so it’s no surprise, but it seemed to me that Hawking was talking nonsense. To be sure that La Repubblica hadn’t given an inaccurate summary, I bought the book, and my suspicions were confirmed.
The book cover describes Mlodinow as a first-rate popularizer and screenwriter of several episodes of Star Trek, and this is evident from the magnificent illustrations, which seem designed for a children’s encyclopedia of yesteryear, colorful and fascinating, but explaining precisely nothing about the complex physical-mathematical-cosmological theorems they should be illustrating. Perhaps it wasn’t the best idea to entrust the fate of philosophy to people with pointy ears.
The book opens with the peremptory statement that philosophy now has nothing more to say and that only physics can tell us (i) how to understand the world we live in, (ii) what the nature of reality is, (iii) whether the universe has need of a creator, (iv) why there is something instead of nothing, (v) why we exist, and (vi) why this particular set of laws exists and not another. As we can see, these are standard philosophical questions, and the book shows how physics can respond in some way to the last four, which seem the most philosophical of all.
To attempt to answer the last four questions, answers are required for the first two questions—in other words, what does it mean that something is real, and do we know the world exactly as it is? When they are taught philosophy, Italian schoolchildren start off with questions such as: Do we learn by adjusting the mind to the thing? Is there something outside us? Or are we the kind of beings envisaged by Berkeley, or, as Putnam says, brains in a vat?
The answers that this book offers are essentially philosophical, and if it weren’t for those philosophical answers, then not even physics could say why it knows and what it knows. Indeed, the authors talk about a “model-dependent realism”—that is, they assume that “there is no picture- or theory-independent concept of reality.” And so “different theories can describe the same phenomenon in a satisfactory way through disparate conceptual structures,” and all we can perceive, know, and say about reality depends on the interaction between our models and that something which exists outside, but which we know only thanks to the form of our perceptual organs and our brains.
More wary readers might recognize the ghost of Kant, but certainly the two authors are proposing what is known in philosophy as holism, which some philosophers call internal realism and others constructivism.
As we can see, this book is not about physical discoveries but about philosophical notions that support and justify the physicist’s research—and competent physicists cannot avoid asking questions about the philosophical foundations of their own methods. This is something we already knew, just as we already knew something about the extraordinary revelation, thanks to Mlodinow and the Star Trek crew, that “in ancient times people instinctively attributed violent acts of nature to an Olympus of spiteful and malicious gods.” By heavens and by Jove!
2011