[ksdale]

These categories exist, but parent's main example was diet/nutrition, which should fit into the hard science bucket because it's chemistry/biology, but currently involves a lot of soft science-y type studies because it's got so many moving parts.

I'm not sure making a distinction like that is particularly useful, in any case. I think perhaps that people who have studied a lot of science can already make the distinction fairly easily, and having phrases like hard and soft science just serves to create assumptions where they needn't exist.

[LeifCarrotson]

Some would group biology into a soft science because the margins for error must be relaxed or softened; one cannot eliminate potentially confounding factors from a biological experiment because each organism is unique and fractally complex.

Another categorization is the "natural sciences" and the "social sciences". Natural science is often split into "life science" and "physical science", again because biology is difficult.

[BitwiseFool]

I also wonder if we can take it a step further and apply a sort of "instance" versus "principle" science. 'Instance Science' is composed of studies that are trying to observe or experiment with something that is heavily influenced by uncontrollable variables and is highly likely to change. In some sense, the results are more like a snapshot in time than a durably reproducible phenomenon. What we typically call "soft science" and all those studies facing a reproducibility crisis fall into this bucket. Instance Science maps poorly onto "the real world".

Contrast that with 'Principle Science' in which studies are not affected by nearly as many uncontrollable variables and is more closely related to demonstrable cause-and-effect phenomena. The best examples are chemistry and physics. Biology is tricky to categorize in this because I see elements of both in it. For instance, a study investigating whether or not taking an increased dose of Vitamin B helps energy would most certainly belong in Instance Science, but the underlying mechanism of how Vitamin B is involved in the Krebs Cycle is Principle Science.

This idea is still in it's infancy and I'm curious to know people's thoughts on this distinction I'm trying to elaborate on.

[h2odragon]

Nutrition isn't a "hard science" because people digest food differently, and that varies over time. We adapt. Your first week of a bean diet will be harsh but after the 3rd year you're probably ok. or dead. Some people wouldn't ever adapt to it.

There's "hard science" there but to throw a rope around the whole field is more of an exercise in faith, that there is One True Diet for All People.

[quantified]

Not at all. Adequate science would tease out all the suitable variables for each individual’s diet at any time and situation for their stage of life. Which will include the details of current internal biome, current infections, medical history of their digestive and other organ systems, metabolism cycles, and many more things. And for which outcome where outcomes compete: cancer likelihood, bone health, sperm count, mental dexterity, fat content, etc.

The fact that there are too many variables and that it’s overly challenging to adequately measure them, coupled with challenges in studying people (ethics, self-assessment blind spots, laws against various options) makes nutrituon a squishy science, neither soft (people stuff like economics or psych) nor hard.

[h2odragon]

Like weather forecasting but worse. Nicely put. "oobleck science" on this continuum perhaps.

[ksdale]

Does the fact that people digest food differently make a difference? I feel like the way food is digested is "knowable" in a way that physics is knowable, we just don't have adequate tools to measure all the complexity yet. As opposed to lots of things about sociology being "unknowable," like Asimov's Foundation being fantasy (probably).

In any case, I was attempting to make the point that hard science and soft science are anything but settled categories, which seems borne out by the responses.