It looks like the laws of physics include "free parameters", constants that we feel could well have had other values than they do. It does not appear that these parameters can all be derived from more fundamental laws that have no free parameters.
Analogous phenomena occur in ethics. If to save your life, I must suffer a minor pain for a second, it is my duty to make the sacrifice. If to save your life, I must suffer constant torture for decades, it is not my duty to do so. As one increases the amount of my suffering to be weighed against your life, at some point one transitions from duty to supererogation (and perhaps eventually to just imprudence). Similar phenomena come up when deciding between goods to people with whom one has different relationships (saving n of one's cousins versus m strangers), when deciding between risks and certainties, etc. It does not appear that these parameters can all be derived from more fundamental laws that have no free parameters. (The best proposal for doing so is utilitarianism, and that just doesn't fit the moral data.)
And there are analogous phenomena in epistemology. For instance, there is the question of how quickly one should make inductive generalizations (in the Bayesian setting this comes to questions like: how high should be one's priors for generalizations).
In physics, the existence of free parameters is strong evidence for some sort of contingency in the laws. There are two ways to have such contingency. The first is to say that there could have instead been other laws. The second is an Aristotelian story on which the laws of physics are necessary but are conditional on the natures of things (e.g., if x is an electron, it behaves thus-and-so), and there could have been other things in the universe with other natures (e.g., shmelectrons instead of electrons) and then other laws--those with antecedents concerning the things with the other natures--would have been relevant.
The first approach raises a problem of explanation: Why are these the laws? The second approach reduces the explanatory question to a different explanatory question that we had anyway: Why are these the entities that exist?
In ethics and epistemology there are two options that can't be taken seriously in physics. One might, for instance, be a subjectivist of some stripe about the parameters (say, by being a subjectivist about all of ethics or epistemology, or just about the parameters). Or one might try to bring in vagueness to solve the problem--maybe it's vague at what point the needs of a larger number of strangers take precedence over a smaller number of cousins.
Vagueness does not, I think, solve the problem. For even if it's vague what the parameters are, it's not completely vague. It's non-vaguely true, for instance, that one should save a billion innocent strangers over one close relative. And subjectivism gives up too quickly.
It would be nice if one could give the same account of the free parameters problem in all three disciplines. Some accounts do not have much hope of doing that. For instance, one might solve the free parameters problem in physics by supposing that there is a multiverse with many different laws, either selected at random or with all possible laws exhibited, and it's just rock bottom that these laws are the laws where they are laws. The idea that there would be such variation in the moral or epistemological laws, with no explanation of the variation, is very unattractive.
There is a uniform Aristotelian story about all three free parameter problems. The parameters are necessarily what they are given the natures of the beings (physical beings, moral agents and epistemic agents) involved. The explanatory burden then shifts to the question of why these are the beings that exist. There is also a uniform divine choice story: God sets the parameters in the laws of physics, ethics and epistemology in a way that makes for a particularly good universe.
But there are, of course, non-uniform stories. One might, for instance, take the Aristotelian story about laws of physics, and a divine choice story about ethics and epistemology. But uniform stories are to be preferred.