Science: seeking examples of distinctions that are useful but spurious

Can anyone think of examples from science or any domain of inquiry where a conceptual distinction turns out to be unprincipled/spurious/epiphenomenal/etc. but is nonetheless still useful practically or methodologically? I.e., something for which we might say, “We know that the distinction between X and Y is spurious, but despite that, looking at things believed to be category X rather than category Y tends to be fruitful for learning about or investigating blah blah blah.”

The closest example I can think of is the idea that racial categories are biologically unprincipled but despite that are still important sociologically. But this is an imperfect example since it shifts the domain of inquiry between biology and sociology and I’d like a case where the baselessness and usefulness are internal to one domain.

centrifugal force doesn’t really exist, but it can simplify things to pretend that it does

Almost all classifications in science are, to some extent, spurious. The most obvious one is that of the species. There’s no definition of species that really works the way you want it to in all situations, and that’s to be expected since evolution is continuous in nature and so any dividing line we draw is bound to be arbitrary. The concept is nevertheless useful.

The idea of light: waves vs. particles? From my physics classes long ago, we changed the model we were using, depending on what we were measuring.

0! (zero factorial) - it makes no sense in any realistic way, yet is very useful in certain calculations (combinations and permutations; Poisson distributions, etc.)

Sundog, does not the proven differences in black, white and oriental races (age at maturity, skeletal formation, basic IQ, etc) establish metrics that are valid ? ?

Please, everyone, I intend my observations to be totally devoid of PC and racial bias.

From a zebra to a mule to a thorobred, the differences in utility are more notable than all similarities . . .

Sure it does. How many way are there to arrange zero items? Just one. Or, since (n-1)! * n = n!, and 1! = 1, then 0! must also be 1. Or, if n! is all integers from 1 to n multiplied together, then 0! is no items multiplied together, and the empty product is equal to 1.

Heat and cold. Cold is just the absence of heat, but the processes of making more heat and making more cold are quite different, for example, in buildings, in people, and so on.

MRE - meal-ready-to-eat.
strong/weak acid
tidal wave
free market
fair value

A laughable claim, Mister Bond.

This depends on what you think counts as something existing. On some accounts, forces do not really exist at all, they are all just mathematically useful fictions, and the relevant things that really exist are, perhaps, motions and fields. On others accounts, centrifugal force exists just as much as any other type of force you care to name. And yes, I dare say there are ontological theories under which some forces exist, but others, including centrifugal force, do not.

According to some theories of the mind-brain relationship, mental states and entities (including things like thoughts, beliefs and desires) do not really exist (only brain processes do), but they are a necessary fiction for humans to be able to relate to one another (or even themselves).

A related view is that there is really no such thing as free will, but that we have to pretend that it does in order for society to function; in order to be able to hold people responsible for their actions (including crimes), for instance.

This relates to the concept of measurements that are not useful in and of themselves, but the results can have practical value for measuring something else. For instance, if you were trying to create a variable for paranoia in a given population (a practical impossibility to measure), you might use a proxy variable instead: gun sales, survival kit sales, elaborate security systems, etc.

In fact, I believe science is full of measurements such as you describe, i.e., that have no intrinsic value but can serve as conceptual catalysts (which would be a great name for a rock band that plays near MIT).

Black is not a colour, but its useful to treat it like it is.

There are many “white lies”, no pun intended.

eg that salt is ionic and water is molecular.

Well as you know, neutral water is 10^-7 Molar ionic H+/OH- …

Then there are crystals , and glass (amorphous… the atoms aren’t anywhere in particular…)

To me, the true value of a measurement seems spurious. All statistics are centered on the hypothetical true value but in reality its just a concept.
For example, you can measure the length of a pencil using different scales and it will come out to be X in +/- <delta> where delta is the measurement inaccuracy. We tend to think of X as real, but it is just hypothetical - you can never really measure it. (It gets even more complicated when you bring in fractals)

The other somewhat spurious concept is that of a point - something that doesn’t have any dimension but EXISTS! and the line by extension

I think the point is that, while there are clear distinctions between races, it fails as a classification system. First, we have many mixings. Second, there are huge differences between (say) Nigerian blacks and Ethiopians blacks, as there are between Norwegian whites and Italian whites, or Japanese Asian and Thai Asian. What we think of as “race” is better classified as “national” (or tribal), and we have today enough marriages between groups that the distinction gets blurrier and blurrier. Hence, it fails as a classification system.

Not to say anything about why someone with one black parent and one white parent is considered “black.” They’re half-and-half.

In much the same way that the example of “hot” and “cold” is a spurious classification. Sure, 200 F is clearly “hot” and -30 F is clearly “cold,” but as a classification system it fails miserably: how about 45 F? There are conditions under which you’d call it “warm” (coming from Chicago’s couple of weeks below zero, say) and conditions under which you’d call it “cool” (in mid-August, say.)

I suspect that the OP is presuming that most distinctions are based in cold, hard, objective reality, and that’s why [s]he’s asking for examples of the exceptional cases, where the distinctions are spurious and subjective. If I am correct, then I think we’ve amply demonstrated that the OP is mistaken. Very little in this world is cold, hard, and objective.

Everything I’ve read suggests greater differences between individuals than the racial group to which they are assigned.

And for that matter, there is significantly more genetic diversity within Africa than there is in the entire rest of the world combined.

Oh, and centrifugal force is exactly as real as gravity. If you’re going to argue that centrifugal force “doesn’t really exist”, or whatever, then to be consistent, you should argue the same for gravity.

Back when I was teaching, I used to bring this up frequently: specifically, while humans like to put things into neat categories, more often than not the reality is that most things lie more on a continuum.

For example, we categorize the electromagnetic spectrum into gamma rays, X-rays, UV, visible light, infrared radiation, and radio. We further categorize visible light by colors, and we can all agree that a light is yellow or green. However, on the spectrum, where does “yellow” stop and “green” begin? Where is the dividing line between “soft” gamma rays and “hard” X-rays, and is the dividing line anything other than arbitrary?

In chemistry, we teach that two types of bonding are ionic and covalent bonds. However, students later learn that these are just two extremes of the same phenomenon, that “polar covalent” bonds exist, and that instead of two neat categories, the actual character of bonds lies on a continuum (depending on the the electronegativity difference of the atoms in question).