The history of science is littered with cases in which a thing turned out not to be a thing.
Phlogiston, the substance purportedly released when something burns, is perhaps the most famous example. Phlogiston was once widely believed to be a thing. But it is not actually a thing. It doesn’t exist. As a modern day example, this piece argues that the famous Dunning-Kruger effect in psychology doesn’t actually exist, that it’s just a statistical artifact. And many ecologists would argue that there’s no such thing as a “pristine” habitat–that human impacts on the planet are so pervasive that no place is free of them.
There are other ways in which a thing can turn out not to be a thing, besides not existing.
- The thing could be many things, rather than one. Think of scientific terms that have various different meanings, each referring to some distinct thing. In an old post, I argued that ecological “stability” is really many different things rather than one thing. As another example, a few ecologists have argued that the concept of “ecosystem engineering” is too broad to be useful. Ecosystem engineering, defined as any effect of an organism on its physical environment, is something in which every organism engages, but in such multifarious ways that it’s not helpful to put them all under the same umbrella. Ecosystem engineering is really a bunch of unrelated things that shouldn’t be lumped together.
- The thing could be vaguely defined. X isn’t really a thing if nobody has any idea what X even is. For instance, philosopher of science Ken Waters has argued that “gene” is such a vague concept that it’s not really a thing (thought note that he also thinks that the vagueness of the “gene” concept is a virtue). As another example, Rohwer and Marris argued in a recent paper that “ecological integrity” is not a thing, because the concept is too vaguely defined. As a third example, Rees et al. (2012) argued that the heuristic concepts of “importance” and “intensity” of competition among plants were so vague as to be effectively undefined and thus unmeasurable. As a non-scientific example, think of mystic Henri Bergson’s idea of “qualitative multiplicity“.
- The thing could be undefined or nonsensical. There was a time when some mathematicians thought that negative numbers weren’t a thing, for this reason. And a time when some thought that imaginary numbers weren’t a thing, for this reason. How could you have a negative amount of something? How can make any sense to speak of numbers that aren’t even on the real number line? And to this day, the fraction 2/0 is not a thing, because it’s undefined.
- The thing could be a contradiction in terms, like an unmarried husband.
- The thing could be a concept that’s useless, misleading, uninterpretable, or pointless. As a deliberately silly example, think of “zargledoodles”, which I just made up. Zargledoodles are housecats, pizzas, and the planet Mercury. A “zargledoodle” is not a thing, because there is no point to lumping together housecats, pizzas, and the planet Mercury into a single category. As a non-silly example, Chong et al. (2019) argued that the concepts of “stabilizing mechanisms” and “equalizing mechanisms” in modern coexistence theory are not things, because they are inextricably interdependent. So that treating them as two separate things is either misleading or uninterpretable. As a second non-silly example, I’ve seen some physicists argue that “dark matter” isn’t a thing. Rather, it’s just a name we’ve given to a placeholder or “fudge factor” that we’ve inserted into our model of the universe, to make the model fit the observed data.
Sometimes, a sign that X isn’t really a (single) thing is that no one can agree on how to measure it. Rees et al. (2012) discuss the many proposed indices of competitive “importance” in this context. Or think of the ongoing disagreement as to how to define and measure “alpha diversity” and “beta diversity”. Is that disagreement because we’re still figuring out how to measure a single, well-defined thing, like 19th century physicists trying to figure out how to measure the speed of light? Or is that disagreement because “alpha diversity” and “beta diversity” aren’t single things? Or maybe aren’t even well-defined things at all?
Often, there’s disagreement as to whether X is a thing or not. Plenty of ecologists disagree with Chong et al. (2019), and think that stabilizing and equalizing mechanisms are things. I’m sure some ecologists disagree with Rohwer and Marris and believe that ecological integrity is a thing. Etc. Those sorts of disagreements are what this post is really about! It seems like it’d be hard to make progress in ecology, if some of the things we’re trying to study aren’t actually things, or if there’s appreciable disagreement as to whether they’re things or not.
Please help me get some anecdata on this by completing the poll below. It’s a list of various ecological concepts. For each of them, indicate if you think it’s a thing that we can measure, a thing that we can’t measure, many things rather than one, or not a thing. If you think it’s not a thing, please choose the option that best captures your reason for thinking it’s not a thing. And if you don’t know or aren’t sure, there’s an option for that.