HOW WONDERFUL IT WOULD BE to have a “Theory of Everything.” So say string theorists in physics who believe they may have found one to unify the four basic forces of nature.
(They use the abbreviation TOE to refer to any such theory. I will, too, whether or not it is string theory.) So thought physicists beginning in the seventeenth century who espoused the “mechanical philosophy” of nature.
So more recently say two prominent philosophers, Thomas Nagel1 and David Chalmers.[133] [134] Nagel has in mind a panpsychist teleological theory that will unify the mental and the physical. Chalmers' “aim is to specify the structure of the world in the form of certain basic truths from which all truths can be derived.”[135]Although those who want a TOE have somewhat different ideas in mind, there is a common, if rather nebulous, core idea: science should aim to produce a grand, unifying theory that can explain everything on the basis of fundamental laws and constituents in the universe—i.e., laws that have no further explanation and constituents that are not analyzable into anything else. What exactly are seekers of a TOE trying to find (e.g., what counts as “everything?”)? Why would it be wonderful to find such a theory? And why suppose that there is or even could be such a thing?
Proponents of the idea of a TOE offer very general empirical, or a priori, or methodological reasons for supposing that a TOE exists, or at least that it would be a good thing if it did, whether or not that theory is the one they are attempting to develop. Their claim is that some TOE does exist, or at least that it would be a good thing if it did. My main concern in what follows is with the very general reasons they offer for such a claim. These will be examined in sections 4 to 7. In section 1, I begin with some particular theories or programs that, defenders believe (or once believed), if developed in appropriate ways, would be or become TOEs. In section 2, I consider, more generally, what basic constraints a TOE is supposed to satisfy.
In section 3, I ask whether any of the theories or programs cited in section 1 is a TOE. In the remainder of the chapter, I discuss the very general reasons offered for seeking such a theory and I argue that they are not compelling.The idea that there exists a TOE, and if so, that scientists should discover it, is a speculation—indeed, a very grand one. So far, no such theory has been found and, I will argue, the reasons offered for supposing that one exists do not rise to the level of evidence sufficient to believe such a supposition (in anything other than a subjective sense of evidence). ^at’s what makes it a speculation (in a nonsubjective sense). But, as I have claimed in earlier chapters, a speculation can be evaluated by considering (objective) epistemic as well as non-epistemic reasons for it that are supportive, even if not strong enough to establish it or count as evidence sufficient to believe it. TOE enthusiasts—both scientists and philosophers—attempt to do at least that much, while some, denying that it is a speculation, give what they take to be much stronger evidential reasons for thinking that a theory of everything exists. There are also TOE theorists who suggest reasons for supposing that it would be a good thing if a TOE does exist and should be found. My purpose here is to examine all these reasons, and reject them. It is also to argue that science can and should proceed very well without a TOE and without presupposing that there is one. TOE theorists speculate about the existence, as well as the value, of a TOE, but their speculations are without merit.
1.