The original post said plumbing, not sanitation in general. Plumbing mostly solves a problem that arises when you have large groups of people. An individual or a small tribe can keep the waste and drinking waters separate by walking downstream a bit.

>If sanitation is a "social problem" then everything is a social problem

Social = society, keep that in your head.

The vast majority of problems you are going to face in your life are social problems because you live in a vast interconnected society with millions/billions of other individuals.

And it is important to remember that almost all problems are social problems, we get a quite a few of the libertarian types on HN that think "I'll just ignore other people and now I've solved every problem in the world". It's why this group of people thinks this way, it makes the problem way easier if you ignore reality.

Money, and the assorted scams around it, regardless of what type of money it is, is a social problem by definition.

Sanitation: If your neighbour has unmanaged sewage, it is certainly not a problem that is limited to them.

Health: If your neighbour has a contagious disease, that is going to be an issue for society as well.

Are we going to pretend that COVID as a problem doesn't fit your chosen definition perfectly: "two people to have it, and that they must have it in relation to each other, which is to say, some sort of social interaction or communication must be involved as well."

Sanitation and health are social problems because if they are not handled they have an extreme effect on society in general. Hell, for plumbing we ONLY care about it as a social problem. If you go live somewhere far enough away from people, we don't care if you shit in a bucket. If you live in a city, we absolutely care about the social effects of not having sufficient plumbing.

If my neighbour has a broken TV, that's a problem that will never affect society. If my neighbour has a contagious disease, or even a non-contagious condition, there are a LOT of ways that affects society.

Same with a neighbour with plumbing that isn't up to code. There's a reason we send government agents in to verify plumbing installations, but we don't give two shits about your TV setup.

I suspect that anyone that says that plumbing or health is not a social problem is living in a place where those things are handled well enough as a social problem that you have never seen what happens when they aren't handled.

I agree with you on the uselessness of definitions that don't distinguish anything, and I think your conceptualisation of a social problem as being something that requires multiple people to interact (like a scam) is useful, admits a very clean boundary, and deserves a name. I would call such a problem a purely social problem. But I think there is a broader concept of "social problem" that makes sense too, even though it lacks such sharp edges.

I think it's reasonable to say that a problem is a social problem to the degree that its severity as experienced by one person depends on other people's behaviour.

If I accidentally drop a rock on my own foot, this seems to be obviously not a social problem. But if I am more likely to be carrying a rock in the first place, or less likely to be wearing protective shoes, because of how society is organised, then to that extent I claim that it is a social problem. This is not an abstract example: Over time, changes in society's attitudes to dangerous kinds of work have directly, and indirectly through health and safety legislation, led to massive reductions in workplace harm since the Industrial Revolution.

Under this rubric, all it takes for a problem to be social is for it to be possible to imagine that society being organised differently would lead to a different level of suffering. Does this lead to nearly all problems being classified as social problems? Yes -- but that is not a problem in itself, that is just an accurate picture of reality! It is still useful -- indeed much more useful -- to place problems on a spectrum of social-ness; nothing "collapses" unless we are determined to make a black-and-white distinction.