[Kaiyou]

Because most humans behave sufficiently different from each other. Even if you experiment on a subset of humans and get knowledge about this subset, a different subset of humans could react completely different. It's so bad that even the same subset of humans could react completely different if you do the same test 50 years later.

[feanaro]

> Even if you experiment on a subset of humans and get knowledge about this subset, a different subset of humans could react completely different.

They could, but that does not mean they do. There are quite obviously rules and patterns to much of human functioning. Denying so seems like human hubris.

Even if each human displays unique behaviour for a particular trait, knowing that it is so for that particular trait is useful and therefore still amenable to scientific exploration. Even if humans reacted randomly in some situation, the random behaviour would be subject to a probability distribution and knowing it would be useful.

It's hard for me to see where exactly the leap to "it's impossible to study human behaviour scientifically" is necessary, particularly when we have so much evidence to the contrary.

[Kaiyou]

It's not science if you don't reliably get the same output if you provide the same input. It's useful, sure. But it's not science.

[feanaro]

Sorry, but this just sounds like a deepity. Science is a process, not a result.

It holds for most of science most of the time that you don't reliably get the same output if you provide the same input (because you don't know all the variables or the entire set of equations). Only when a phenomenon is completely known does this stop being true.

But when is a phenomenon completely known? After all, for a long time we've known classical mechanics to be completely known... Except it wasn't. And during the time we thought it was, you could get into exactly the type of situation you describe above: for the "same" input, you could get a different output, depending on the components of the stress-energy tensor you were not aware were relevant. The effect was subtle there of course, but there are many examples where it's not (e.g. the entirety of biology and medicine).

So I disagree with this description of science.

EDIT: Also, it completely slipped my mind the first time around because it's such a stupidly strong counterargument, but by your definition the entirety of modern physics (quantum mechanics, quantum field theory and beyond) is not science.

[Kaiyou]

Science is useful because it has the power to predict. It gains this power from getting the same output when providing the same input. If what you are doing doesn't have the power to predict it's not science. You can still apply the scientific method to what you are doing and if you're applying that method you might as well call yourself a scientist and what your doing science, but then again, a few hundred years ago scientists didn't yet know that things like alchemy weren't science, so they applied the scientific method to it and figured out that it isn't useful.

[dragonwriter]

> Even if you experiment on a subset of humans and get knowledge about this subset, a different subset of humans could react completely different.

The same is true of chemicals, rocks, or lots of other categories of things subject to scientific inquiry. In fact, interesting scientific results tend to come from how the behavior of different subsets of categories like that behave in similar conditions, rather than being made impossible by such differences.