The question “why do physical laws have their specific form?” is a philosophical trap: any attempt to explain the laws of physics must itself rely on some law or regularity, making the question self-undermining. Host Curt Jaimungal walks through why this seemingly innocent query resists resolution, examining how physicists and philosophers have tried—and failed—to escape the circularity.
How Physicists Try to Explain Laws (and Why It Doesn’t Work)
Physicists point to deep structural results as explanations for why things work the way they do.
Wigner’s classification shows that particles are representations of spacetime symmetry groups, so their properties follow mathematically from symmetries.
Noether’s theorem links symmetries to conservation laws (e.g., time symmetry → energy conservation) under variational principles.
But there’s an inverse problem: multiple Lagrangians can produce the same physics, so symmetries don’t uniquely determine the laws.
Inverse Noether theorems exist (Harvey Brown’s work) but require extra constraints and don’t fully resolve uniqueness.
Some conservation laws exist without variational principles at all (e.g., dissipative systems).
When pressed further, physicists retreat to grander meta-theories, each of which just pushes the problem back.
Tegmark’s Mathematical Universe Hypothesis: reality is mathematics; all consistent mathematical structures exist as universes. But this requires explaining why these structures and not others, and why math has physical instantiation at all.
Lee Smolin’s Cosmological Natural Selection: universes reproduce through black holes with mutated laws, optimized for black hole production. But this needs a meta-law governing reproduction.
Wheeler’s “It from Bit”: reality is fundamentally information (yes/no answers), and laws are patterns in this cosmic questionnaire. But what governs the laws of information itself?
Each proposal either inherits the same problem at a higher level or introduces new unexplained foundations.
What Do We Even Mean by “Law”?
The word “law” is itself philosophically loaded and hard to pin down.
Is F=ma a law or a definition? Is the “law of the excluded middle” a law in the same sense? Does renaming it a “rule” change its status?
Philosophers have sharpened this into a genuine debate.
Humean view (championed by David Lewis): laws are just patterns in the mosaic of events—they describe regularities but don’t govern anything. Laws are whatever gives the best combination of simplicity and strength in systematizing facts.
Non-Humean view: laws have genuine prescriptive force—they constrain what can happen, not just describe what does. Eddie Chen’s recent paper frames fundamental laws as constraining physical possibilities (discussed with Barry Loewer).
But this risks circularity: laws define what’s physically possible, and physical possibility is defined by laws.
Constructor Theory (David Deutsch) also frames things in terms of possible vs. impossible, which Jaimungal sees as assuming a “law of possibilities”—a law of laws.
Barry Loewer’s “package deal” account: laws and natural properties come together and bootstrap out of circularity. But this raises the question of why this package and not another.
Distinguishing laws from “accidents” already presupposes a criterion for lawhood, which itself depends on laws—another circle.
The Justification Problem: Agrippa’s Trilemma
Any attempt to justify or explain laws faces Agrippa’s trilemma (also called Münchausen’s trilemma)—three unsatisfying options:
Infinite regress: each law is explained by a deeper law, ad infinitum. Maybe there’s a final law at the bottom, maybe not.
Circular reasoning: laws explain themselves, which is no explanation at all.
Foundationalism (brute fact): you assert something is just fundamental and stop asking. Most physicists implicitly choose this (e.g., “the universe just has these symmetries”), but it’s an admission of explanatory defeat, not an explanation.
This mirrors other self-undermining questions.
Asking “why is logic logical?” requires using logic to examine logic. You can’t stand outside it.
Kierkegaard would say this is where reason gives way to faith.
Jonathan Pageau’s consistent question: “From where do you stand when making a claim?” There is no view from nowhere—every perspective has embedded values.
Recent Attempts to Escape
Recent papers keep trying to square the circle.
“A Law Without Law”: appeals to emergent regularities from quantum mechanics. But quantum mechanics itself has the Schrödinger equation and the Born rule—so it’s law without law in name only, “like alcohol-free beer.”
QBism: laws are features of our beliefs, not reality, dissolving the problem by denying there’s anything to explain. Jaimungal finds this unsatisfying.
David Deutsch has developed views on what distinguishes good from bad explanations, but even his framework runs into the trilemma.
The Limits of Explanation
Asking physics to explain its own laws may be like asking a system to step outside itself and justify its own foundations—akin to asking English to explain why it has grammar.
The concept of “explanation” itself seems to presuppose lawhood: to explain something is to connect it to something else via a reliable pattern—which is just what a law is. So asking for an explanation of laws is asking laws to subsume themselves.
Even a successful “theory of everything” wouldn’t resolve this.
You’d still need to explain why mathematics at all, why these mathematical structures have physical instantiation, and why math corresponds to physics.
Jaimungal notes he doesn’t find the “unreasonable effectiveness of math” obviously unreasonable, but he oscillates on this.
The real lesson isn’t that physics has failed—it’s that explanation itself has limits.
Math has limits (Gödel’s incompleteness, though Jaimungal thinks these are overblown). Science has limits (Putnam’s model-theoretic argument shows we can never know if we’ve found the “true” explanation, since any theory has multiple models).
Explanation only makes sense within a broader scaffolding of regularities. It’s not a failure of intelligence or theory—it’s a feature of what explanation is.
The practical response (“shut up and calculate”) is fine for doing physics but is “intellectual surrendering” for understanding reality.
Jaimungal’s present view: any possible answer to “why these laws?” would itself be a law or require its own explanation. This isn’t a problem to be solved but a boundary of what explanation can do—subject to revision if a genuinely new kind of explanation emerges.
