Over at The Monkey Cage, Andrew Gelman asks what are the (relatively) settled matters in social science? What do we really know, no doubt about it? He notes that it’s difficult to come up with any, since matters that some people think are settled often aren’t considered settled by others.
He also notes that just because something is settled doesn’t necessarily mean we should stop studying it. For instance, once everyone is satisfied that phenomenon X happens, that sets the stage for follow-up studies examining why phenomenon X happens, how to manipulate phenomenon X, etc.
There are lots of important bits of ecology that are settled, I think (and I suspect the same is actually true in the social sciences, if you restrict attention to sufficiently-basic claims). Just listing bits of ecology that are settled would result in a pretty long and boring list. So how about we try to list bits of ecology that were once controversial but are now settled?
In some ways, this gets back to my old post asking readers to name examples of productive and unproductive debates in ecology. But it’s not exactly the same, I don’t think, since a debate can be productive because it clarifies issues, reveals unspoken assumptions, etc., even if it doesn’t lead to a settled resolution.
I suspect one challenge in coming up with this list will be in deciding the level of precision at which any given claim can be considered “settled”. For instance, when we do predator removal experiments to look for trophic cascades, we mostly find trophic cascades (Shurin et al. 2002). So broad qualitative questions like “Do trophic cascades occur?” have settled answers (“Yes, at least everywhere we’ve looked so far, and we’ve looked in lots of different places”). But more quantitative or refined versions of the same question may not have settled answers. For instance, “Are trophic cascades typically stronger in aquatic than terrestrial systems?” might not be considered settled.
Of course, as many have joked, the settled answer to controversial questions in ecology often turns out to be “it depends.” But I’m hopeful that we can come with some examples where the settled answer is not “it depends”, or at least is a more elaborate version of “it depends” (“it depends on factors X, Y, and Z, in the following ways…”)
So, what once-controversial matters in ecology are now settled?
p.s. Even things that seem settled can occasionally turn out to be wrong. Think of classical Newtonian physics being overturned by Einsteinian relativity.