6

From what I gather, scientific laws according to Humeans are merely descriptions of the regularities that occur in nature. Anti Humeans think laws have some sort of prescriptive/causal power which leads to the familiar notion of things “obeying” laws.

Does this mean that on the Humean view, the regularities themselves are simply coincidences? After all, it is easy to imagine a universe where gravity works differently here vs. there. It is also easy to imagine gravity or many other forces working differently now vs. later. If laws are prescriptive, it gives us an explanation for why gravity works the same way here vs. there. If they are not, should one have to accept that this is a miracle?

From another question on here earlier, and most comments on this site, it seemed that Humeanism was the prevailing view with regards to laws. But according to the recent PhilPapers survey here, most philosophers actually seem to be anti Humean.

Improve this question
14
  • 2
    "laws" are our (human) way to describe reality; maybe our description is faithful. The grounding principle of science (and most of philosophy...) is that there is a reality independent of human mind and that we can use experience and reason to try to describe and understand it.
    – Mauro ALLEGRANZA
    Commented Dec 21, 2023 at 10:15
  • 1
    Why is reality regular then? Why doesn’t salt dissolve in water today and not the next? @MauroALLEGRANZA If laws were prescriptive, it would explain why it’s regular by virtue of it being a law. If they are descriptions, the fact that reality is regular seems to just be an unexplainable coincidence if no law is enforcing the regularities.
    – user62907
    Commented Dec 21, 2023 at 10:21
  • 3
    "Why doesn’t salt dissolve in water today and not the next?" According to our current scientific knowledge, because the chemical structure is salt is "made" in such a way that it interacts with water in such-and-such a way. This is HOW scientific theories describe and explain FACTS: using mathematical formulas (law) to express generalities. Knowledge is to "collect" particulars (facts) under general (laws, abstract concepts): it is a very efficient way humans use to survive.
    – Mauro ALLEGRANZA
    Commented Dec 21, 2023 at 10:34
  • 1
    But that’s just restating the regularity @MauroALLEGRANZA Why does it behave the same way? Your answer simply amounts to “because the structure is such that it does.” But why does that structure lead to a regularity?
    – user62907
    Commented Dec 21, 2023 at 10:40
  • 1
    Humean vs non-Humean: what does it mean? See Hume: "historically, until late in the Twentieth Century, was called the “Humean” account of Laws of Nature was a misnomer. Hume himself was no “Humean” as regards laws of nature. Hume, it turns out, was a Necessitarian – i.e. believed that laws of nature are in some sense “necessary” (although of course not logically necessary). His legendary skepticism was epistemological. He was concerned, indeed even baffled, how our knowledge of physical necessity could arise. "
    – Mauro ALLEGRANZA
    Commented Dec 21, 2023 at 11:13

4 Answers 4

Reset to default
6

As others have pointed out, the most we can normally do is to describe the things we see. We may, one day, find a set of laws that are sufficiently precise to describe everything we see. We may hope that these laws are the same ones as the universe itself, but we will not know.

There are irregular things in nature. Nuclear decay is an example. If you have a line of good-looking apples on a shelf, and one goes rotten, you might attribute it to a bruise that was originally invisible, but allowed the decay to start. If you had a line of (say) Californium atoms, one of the might decay, but (we believe) without any history of damage or decay - just that the wavefunctions of the nuclear components extend a bit beyond the range of the nuclear forces, giving them a finite chance of 'tunnelling out' of the nuclear well and escaping. We accept that some isotopes have a half-life. The laws of thermodynamics are also based on averages of microscopic random behaviours.

What would we do when faced with something unpredictable at the macroscopic scale? Find a video of a compound pendulum. That looks pretty unpredictable. We can then try to predict it. In the case of the compound pendulum, Newton's Laws is enough. If it wasn't, we would try harder.

Improve this answer
1
  • 6
    +1 for "...Newton's Laws is enough. If it wasn't, we would try harder." Here is IMO the "little" but fundamental difference between science and philosophy: for science, if our idea does not work, we "would try harder". For philosophy: we struggle to "modify" the facts in order to match our ideas.
    – Mauro ALLEGRANZA
    Commented Dec 21, 2023 at 12:16
3

Hume's position is better described as a radical agnosticism about the existence of natural laws. He doesn't say they don't exist, but rather that we can never directly observe them empirically. All we can view is their empirical footprint. Since, in general, his view is that we are justified in talking only about what we can empirically observe, speculation about the "real" existence of laws is in the realm of nonsense for a Humean.

He does, however, allow that we are justified in expecting (NOT proving) that the regularities we observe will be reliable. This is his key move to establish a foundation for science without reliance on the metaphysical. A "miracle" in Hume's terms is an inexplicable departure from the regularity of experience. So the universality of gravity would be as expected, it would not be "miraculous," but talk of a prescriptive "law" of gravity would nevertheless be an overreach.

As a gross generalization, it is said that scientists tend to be Humean, and mathematicians, Platonist. As for philosophers, the Humean viewpoint long held sway as a key part of the analytical tradition of philosophy currently dominant in the English-speaking philosophy world. But my own sense is that the pendulum is swinging, and that metaphysics is being rehabilitated as a field of philosophical study (probably as part of a generational shift).

Improve this answer
2
  • Miracles are unexpected things, sneaky! Now we just have to figure out what to expect :-)
    – Scott Rowe
    Commented Dec 21, 2023 at 20:41
  • There have been many papers and books on the "unreasonable effectiveness of mathematics in science" -- many physicists and philosophers are indeed surprised that nature contains regularities that can be described with straightforward mathematical equations.
    – Barmar
    Commented Dec 22, 2023 at 15:25
2

One "middle way" between ante rem realism about laws (laws imposing themselves on the world) and nominalism about laws (laws are just general coincidences) is an Aristotelian in re conception of laws as internal to the objects in the world. A "middle way" between ante rem and in re realism would be monism about the universe:

One compelling argument for existence monism (2000: §2.4, also Schaffer (2007)) is that the complete causal story of the world can be told in terms of the world and the laws without appeal or reference to parts of the world. So, if there were parts of the world, they would be redundant and/or epiphenomenal (see entry). But we shouldn’t posit explanatorily redundant or epiphenomenal things. So, we shouldn’t posit parts of the world. So, only one object—the world—exists.

If the world is a law unto itself, then the world imposes its structure upon itself, or less teleologically-speaking, if the world has a characteristic functionality f(x), then it can (or just does, as time passes) input that function into itself to yield further states f(f(x)) (etc.). At any rate, we can find theories/metatheories of physical laws besides ante rem realism and nominalism, just as we can find such diversity with regards to mathematics (e.g. we might situate intuitionism between realism and formalism, and predicativism between realism and intuitionism, and so on and on).

Improve this answer
2

You state that "it is easy to imagine a universe where gravity works differently here vs. there". The laws of gravity may be the same everywhere, but "how fast we fall down" does work differently here vs. there.

That's why we made the conscious decision to make the laws of gravity describe just the parts of "falling down" that are regular, along with stating which features of a given situation make "falling down" work differently, and how: acceleration due to gravity is not the same from place to place, but if you have objects A and B, the ratio between the acceleration of A and the mass of B divided by the square of the distance will always be the same (and vice versa). The gravitational constant describes that ratio, and the rest of the equation describes how the rest differs from place to place.

Improve this answer
5
  • So, Laws only describe the regular features of reality? Gosh, that's disappointing!
    – Scott Rowe
    Commented Dec 21, 2023 at 20:37
  • 1
    @ScottRowe The regular parts and the manner in which the irregular parts differ. I could have a law that gives the gravitational force pulling me towards the Sun right now, one for the force pulling me towards the Moon 3 hours ago, one the force pulling me towards the dog next door 30 nanoseconds ago, etc. Or I could have one law that says "That force is different in each of those cases, but if you know the mass of the objects and how far away they are, you can figure it out for any case you care to like so: $F = G m_1 m_2 / r^2$.
    – Ray
    Commented Dec 21, 2023 at 20:46
  • The only way we can't have a law at all is if things differ for literally no reason whatsoever, and even then, we could potentially describe it probabilistically. (Or if it's just really really complicated and we can't figure it out.)
    – Ray
    Commented Dec 21, 2023 at 20:49
  • 2
    I think gravity is a terrific example: we have P = m g as a first law, and we can notice that g differs by a few percents between ocean level and the summit of Mount Everest; and then when that law is no longer enough we have F = G m1 m2 / r^2, which can be thought of as a generalisation or complexification of P = m g. This directly answers the OP's question: it wasn't a coincidence that things were following law P = m g on Earth, even though P = m g wasn't the fundamental natural law behind gravity.
    – Stef
    Commented Dec 22, 2023 at 11:16
  • 1
    @Stef And then we notice Mercury's orbit is funny and it's actually G_{μν} ≡ R_{μν} − 0.5 R g_{μν} = κ T_{μν}; ∂^2 x^μ/∂s^2 + γ^μ_{αβ} ∂x^α/∂s ∂x^β/∂s = 0, at which point we start to wonder if maybe P = m g wasn't such a bad approximation after all. :-)
    – Ray
    Commented Dec 22, 2023 at 16:37

You must log in to answer this question.