On the Orderliness of the Universe, Humean Laws of Nature, and Sufficient Reason

Abstract

The universe appears mysteriously orderly. When we search for explanations, the universe has granted us such with overwhelming regularity. And not only that, the nature of the explanation tends to be elegant, as if the universe were pieced together in hand-crafted manner. The laws of nature seem to hold with an almost too-convenient regularity, and formalizations of processes consistently emerge from the other side of scientific inquiry as simple and unifying. These impressions have led many to seek explanation for these patterns which seem increasingly non-coincidental. One route of justification involves appeals to the Principle of Sufficient Reason (PSR) and criticism of Humean perspectives on laws of nature. The basic idea is that the universe is orderly because, as the PSR would entail, things must have reasons/explanations. A Humean perspective, which reduces laws to a bedrock of mere empirical correlation, rejects the need for further explanation. As such, the view appears to provide no grounding for what it observes. Without a necessary underpinning, the Humean perspective can be criticized for the apparently immense improbability that its scattered mosaic of laws could emerge with the level of order and explainability we see.

We make the case however, that such criticisms are flawed. An appeal to the PSR and a rejection of Humean laws are not required to explain the universe as we see it. Criticisms of the Humean perspective fail on two fronts. The first is the implicit acceptance of objective notions of explanation, order, and simplicity, and the second is that of probabilistic fallacies that hastily equate Bayesian likelihoods with posteriors. We begin with a critical investigation of notions of explanation, order, and simplicity to better grasp the nature of the confusion. We advocate a theory of explanation (in ordinary language) as being subjective and based on prior expectations, and order/simplicity as characteristics that are constructed and pursued rather than discovered. We continue with an investigation of probabilistic arguments against Humean laws. We first investigate the nature of possibility and various interpretations of probability to better set the stage for analyzing probabilistic claims. In particular, we analyze the relation between conceivability and possibility that is often employed in such arguments. Then, we investigate various arguments under Bayesian formalisms to question likelihood -> posterior probability assumptions, which depend on equal priors. Questioning such assumptions, the probabilistic arguments can be shown to reduce to ambiguous questions of theory choice. Ultimately, we show that the order in the universe is not as mysterious a phenomenon as one might initially believe and that Humean laws of nature are no worse an explanation than proposed alternatives. We by no means claim to show that one should reject the PSR, but show that an appeal to it is not needed for a Humean to make sense of our discoveries. All things considered, the explainability of our universe does not constitute a good point of support for non-Humean/PSR-ist perspective over Humean ones