In his 1988 classic A Brief History of Time, Stephen Hawking posed a question that has echoed through philosophy of science ever since: what is it that "breathes fire into the equations" of physics, transforming abstract mathematical descriptions into a lived, material reality? The question sits at the intersection of metaphysics and physics, and it has never been satisfactorily settled. For decades, two broad camps have dominated the debate. One holds that the laws of nature are genuine governing forces — a kind of secular substitute for divine command — that compel matter to behave as it does. The other treats laws as possessing some intrinsic metaphysical "disposition," a power embedded in the fabric of things themselves.
In Laws of Nature and Chances, philosopher Barry Loewer offers a third path. Loewer argues that the fire does not come from a supernatural source, nor from an intrinsic power hidden within particles. Instead, it is generated by the activity of science itself. Under this view, the laws of nature are not external scripts that the universe is forced to follow. They are the most efficient and informative summaries of the patterns human inquiry has managed to detect.
The Best System Account and Its Lineage
Loewer's argument builds on a tradition in philosophy of science known as Humeanism, named not for its skepticism but for its ontological parsimony. The core Humean claim is that the world consists of a vast mosaic of particular facts — events, configurations, measurements — and that laws are simply the best way to compress that mosaic into a manageable description. David Lewis, the late Princeton philosopher, formalized this intuition in what he called the "Best System Account" (BSA): the laws of nature are the axioms of whichever deductive system achieves the optimal balance of simplicity and informational strength when applied to the totality of what happens.
Loewer has been one of the most prominent defenders and developers of the BSA for years. What Laws of Nature and Chances appears to add is a sustained treatment of how objective chances — the probabilities that appear in quantum mechanics and statistical mechanics — fit within this framework. This is no minor extension. Probability has long been the sharpest objection to Humean accounts of laws: if laws are mere summaries, critics ask, how can they ground genuine chances rather than mere frequencies? Loewer's response, as characterized in the review, is that chances earn their status precisely by being part of the system that best systematizes the mosaic. They are not ghostly propensities lurking inside atoms; they are features of the description that makes the world most intelligible.
The philosophical stakes are considerable. If laws are governing forces, then explanation in physics bottoms out in something metaphysically robust — a power, a necessity, a cosmic rule. If laws are best-system summaries, then explanation bottoms out in the practice of systematization itself. The universe does not obey equations; equations are the most compressed account of what the universe does.
From Metaphysics to Method
This reframing carries implications beyond academic philosophy. In an era when machine learning systems routinely discover statistical regularities in data sets far too large for human inspection, the question of what a "law" really is takes on practical weight. If laws are best-system summaries, then in principle an algorithm that finds the most compact, most predictive description of a data set is doing something structurally analogous to what physics has always done. The distinction between a law of nature and a powerful empirical generalization becomes one of degree, not of kind.
Loewer's position also sidesteps a persistent theological residue in philosophy of science. The language of "governance" implies a governor; the language of "disposition" implies a hidden essence. The Best System Account requires neither. It asks only that the world exhibit patterns and that inquirers seek the most efficient encoding of those patterns. The fire in the equations, on this reading, is not placed there by a creator or by nature's own hidden machinery. It is a product of the encounter between regularity and the drive to describe it.
Whether this deflationary stance can fully account for the modal force that laws seem to carry — the sense that objects do not merely happen to attract one another but must do so — remains the central tension. Humeans have long been accused of turning necessity into cosmic coincidence. Loewer's book, by extending the framework to chances and connecting it to actual physical theories, tests whether that accusation still holds. The answer may depend less on which metaphysics one finds correct and more on what one is willing to demand from the concept of explanation itself.
With reporting from Notre Dame Philosophical Reviews.
Source · Notre Dame Philosophical Reviews
