I don’t ordinarily plug individual papers in ecology journals, figuring y’all don’t need my help finding individual papers to read and deciding what you think of them. But I’m making an exception because this is important.
Writing in Trends in Ecology and Evolution, the always-thoughtful Mark Vellend reviews philosopher Donald Maier’s new book What’s So Good About Biodiversity? You should click through and read it, because the review (and by the sound of it, the book) are really sobering.
Maier reports being “stunned” that he “could not find a single argument [for the value of biodiversity] that does not have serious logical flaws, crippling qualifications, or indefensible assumptions.” And before you write Maier off as just ignorant, or as someone saying outrageous things to try to sell books, be aware that Mark thinks he’s got a point. Which doesn’t prove the book is right–but does prove it deserves to be taken seriously rather than dismissed out of hand. For instance, Mark discusses the argument for biodiversity based on the ecosystem services it provides–and notes that nobody ever talks about all the ecosystem disservices that biodiversity also provides, such as increased disease risk. And how come ecologists never argue for promoting species invasions on the grounds that it would increase biodiversity and thereby enhance ecosystem services? As Mark pointedly remarks, when it comes to valuing biodiversity, ecologists basically started with a conclusion, and then looked around for arguments to support it. It’s unsurprising that such a backwards procedure yields unconvincing arguments. It’s the same procedure that Scholastic philosophers used to find “proofs” of the existence of God, for instance, and it’s the same procedure creationists use to argue against evolution. Now in fairness, post hoc rationalizations have their place, and often they’re unavoidable. But if they’re really bad rationalizations, and if they’re not even recognized as rationalizations, then there’s a problem.
Which is something ecologists should talk more about–but we mostly don’t, at least in my experience. That’s maybe the biggest problem here. Maier concludes that not only have ecologists collectively been the victims of confirmation bias when it comes to valuing biodiversity, but they’re not talking about it. Maier concludes that there is “tacit agreement among colleagues not to rock the boat of bad reasoning – perhaps out of fear that there is no other way to defend nature and its value”. As Mark says: ouch.
Anyway, consider this another example of why ecologists should read more philosophy.
UPDATE: On Twitter, @frank_burdon asks whether Mark “lacks objectivity” because of his recent PNAS paper showing that local-scale plant biodiversity around the world isn’t changing. I’m confess I’m unclear exactly what “objectivity” means here. But if what’s meant is something like “a thoughtful, knowledgeable, self-aware person who carefully weighs evidence and arguments in order to come to conclusions he’s prepared to defend”, then Mark Vellend is one of the most objective people I know.
UPDATE #2: Just to continue the thought from the previous update, and highlight some things I just said in the comment thread. I’m well aware that Maier’s views are going to be controversial and unpopular. And I’m well aware that some people didn’t like Mark’s recent PNAS paper (though personally I’m not sure why, as I didn’t see any serious technical flaws or wild overstatements in it myself…). It’s for those reasons that I hesitated to post on this; there’s a higher than usual risk of the discussion degenerating into an unproductive shouting match. But I decided to post, as the issue is important, and interesting to me. And because in the past we’ve always been able to trust our commenters to vigorously debate controversial issues without descending into personal attacks, questioning of motives, proof by authority, etc. So let’s all make sure we live up to the high standards set by previous comment threads on controversial topics. One of the best uses of blogs is as a forum for vigorous but productive debate.
UPDATE #3: And just in the interests of being up front about my own views here: I think Maier has an excellent point about general, blanket arguments for the value of “biodiversity”. Insofar as we’re conserving biodiversity in order to achieve some instrumental goal (like maximize the level of some ecosystem service), then I think we’re much better off making narrower, case- and context-specific arguments. Arguments like “In order to ensure provision of ecosystem service X in system Y, we ought to conserve high levels of biodiversity, because alternative ways of ensuring provision of high levels of service X would be more expensive, and because doing so will not have any negative side effects.” If there are any good general, blanket arguments for conserving biodiversity always and everywhere (or preventing species invasions always and everywhere, or pursuing any particular conservation policy always and everywhere), then I suspect they’re based on intrinsic values rather than instrumental values. There’s a large philosophical literature on that, of course, but it’s not one I know well.