What's so good about biodiversity?
What's so good about biodiversity?
Not much, according to this excellent yet overlooked 2012 book by Donald S. Maier
Biodiversity is, in some fundamental way, unsuitable for shouldering the normative load that so many environmentalists, conservationists, and scientists have asked it to carry.
In my last post, I examined the logic behind the European Commission’s proposal to reduce EU pesticide use. Among the questions the Commission left unanswered was one concerning the relevance of the diversity of pollinator species, and I mentioned a 2015 study which suggested that most bee species contribute very little to pollination. So is there anything good about this great diversity of pollinators? Is there any reason to spend attention and resources on preventing the disappearance of many bee species? According to the authors of the 2015 study, you’d better find a different argument than “ecosystem services“:
Conserving the biological diversity of bees therefore requires more than just ecosystem-service-based arguments.
If “ecosystem services” doesn’t work as an argument for preserving (or enhancing) bee diversity, will this argument at least work for other species, or for biodiversity more generally? And if not, are there other arguments that might support biodiversity as a means to a valuable end, or is biodiversity perhaps a valuable end in itself?
Donald S. Maier’s “What’s So Good About Biodiversity“ offers a systematic analysis of these questions. I found this book an excellent and much-needed corrective to the hype surrounding biodiversity, which shows no signs of abating.
Maier’s key message is that commonly proposed and widely propagated theories and arguments about the value of (conserving) biodiversity are deeply flawed. So flawed that biodiversity, properly understood, provides no rational basis for serious efforts to “protect nature“.
The book is written by a philosopher (who nonetheless has a good understanding of the relevant science). And reading the book you realise that the problem with reasoning about biodiversity value is often logical, rather than scientific.
The writing, although dense, is sufficiently clear for non-experts to understand, also thanks to the first couple of chapters equipping the reader with relevant concepts from philosophy and logic, economics and science. If you have been suspicious about theories of biodiversity value, you’ll love this book. Likewise if you want a contrarian perspective on a most favored concept. The book is also simply enjoyable because of the large amount of critical yet fair, logical and comprehensive reasoning it brings to the table, with a likable dose of modesty:
For my part, I have tried mightily to construct arguments that are sound in fact and logic. At the same time, I know that no attempt to address a topic this complex is without flaws; I will not be surprised if you discover some in this book. But I hope that one or two flaws in my reasoning will not dissuade you from the preponderant impression that the reasoning about biodiversity now before the general public, as well as in scientific, economic, and policy circles, is rife with flaws. I hope that you, like me, will not be able to escape the conclusion that a case for natural value cannot stand on such a flawed foundation. But mostly, I hope that this book prods you into reviewing and even reconstructing your own thinking on these matters. As for my own attempt at such a reconstruction in the last chapter of this book, even if you find it unconvincing, I hope that my example will serve to set you free to find something better.
What is biodiversity?
Here is how Maier defines biodiversity (paraphrasing): The diversity of kinds in each of multiple biotic and biota-encompassing categories (see figure below). Key characteristics of this conception are egalitarianism (e.g. every species, or feature, contributes the same amount to biodiversity as any other) and fungibility (e.g. replacing any species, feature or other kind within a category with any other does not affect the amount of diversity). Several other characteristics, such as abundances (and species evenness) and interactions, are noteworthy in being explicitly excluded from Maier’s definition.
Biodiversity is not valuable for (ecosystem) services…
Here is a summarizing paragraph from one of the most devastating sections (6.3), in which Maier discusses the many flaws in the arguments for biodiversity as a provider of ecosystem services:
All in all, the theory that ecosystem services are critically tied to biodiversity is singularly unpromising. The empirical evidence does not support it, for the complete body of facts includes a raft of disservices, which handicap human endeavors rather than benefit them. Also, the nature of many services places them in two broad classes of services that are extremely insensitive to diversity. The logic also does not support it, for the rationales rely on invalid inferences such as those that infer the need for biodiversity from the contribution of a single species. Even the foundational concept of “ecosystem service” seems ill-equipped to shoulder the weight of generalizations that allege the dependence of ecosystem services on biodiversity, for it does not account for the differing circumstances that sometimes make a property a service, and other times a disservice.
What Maier means by “disservices” is first of all that biodiversity is often the enemy of ecosystem services. For example, water purification would go a lot better were it not for the microbes and flora that make people sick. Or take diseases, disease vectors, and the pollination of noxious weeds. More importantly, biodiversity is often an obstacle to valuable (non-ecosystem) services (which necessarily must be included in any unbiased assessment). Here, Maier mentions as an example the case the Cook Inlet, where (the protection of) belugas represented an obstacle to development:
Cook Inlet is an area where exploding gas and oil development has spurred planning to expand the port of Anchorage and possibly build a new bridge, the Knik Arm version of the “Bridge to Nowhere” across the Inlet. The beluga swims – at a typically unhurried 3–9 kph – squarely in the way of the services that promise substantial increases in economic welfare. Whatever small economic benefit the little white whale contributes derives mainly from the amusement it affords people in marine “parks”. So far as Palin and most Alaskans are concerned, the whales should stay there and clear of the development of vastly greater economic goods in the Cook Inlet. There it is unequivocally an economic liability.
In the broader (unbiased) context of (ecosystem and non-ecosystem) services and disservices, biodiversity can fail to be valuable in two ways: First, it fails if the (positive) ecosystem services are outweighed by the disservices and opportunity costs from biodiversity (see examples above). Second, it fails if the service does not critically depend on some significant biodiversity. Regarding the second case, Maier notes that rare and isolated species (whose disappearance would mean lower biodiversity) are unlikely to perform any real positive service. Furthermore, many ecosystem services (such as carbon sequestration, filtering or cycling water, mitigating floods or controlling erosion) make minimal demands on biodiversity. A place wiped fairly clean of vegetative and other diversity can still deliver such services, as long as it supports plant vegetation of any single species. Maier observes that there is a gross superfluidity of species associated with the majority of ecosystem services (remember the bee example I cited at the beginning). For all these reasons, he considers the theory that ecosystem services are critically tied to biodiversity unpromising.
Maier then obliterates one final argument for the proposition that biodiversity underwrites vital ecosystem services, namely the precautionary principle. Here is his summary:
All in all, I believe that whatever force there is behind Ehrlich et al.’s precautionary argument derives from their implicit supposition of a threshold that is the backdrop for a Pascal’s wager on the removal of the next species. The terms of the wager are that
(i) there is radical uncertainty about the outcome of the next extinction, no matter what the circumstances; but that
(ii) one plausible outcome is the irremediable loss of a vital ecosystem service; and that
(iii) there is little to lose by preventing the next extinction, thereby avoiding such a dire outcome.
I have argued that there are fatal objections to all three terms of this wager: So far as terms (i) and (ii) are concerned, we are most often justified in thinking that the removal of a species will have absolutely no deleterious effect. In cases where we believe that a deleterious effect might result, the belief is oftentimes not at all uncertain; we have a good handle on the likelihood with which the harm might occur. As for term (iii), there is often much to lose by doing what is needed to prevent an extinction. And finally, term (ii)’s claim for irremediable loss presumes a radically broad and unqualified inability to adapt that has, at best, fragile support.
...nor is biodiversity valuable for human health…
Maier rejects another popular theory of biodiversity value, namely “biodiversity as a cornerstone of human health” (section 6.5). Pharmaceutical development has little to do with biodiversity. For example, while 86 of the top 150 drugs (in the United States) derive from some living thing, just 20 different species are represented, and domesticated species like the horse, sheep or the fungus Penicillium feature heavily. Maier:
Finally, insofar as the argument for biodiversity as a potential medicinal resource is an economic one, it must soberly account for the vanishingly low probability that the medicinal benefits will actually be realized. That vanishingly low probability entails a vanishingly small expected net present value of the benefits of economic development foregone in order to ensure the protection of the medicine-yielding natural resources. The economic analysis, when honestly done, does not appear to give the answer that environmentalists want. […]
Considerations previously presented in this subsection further weigh against an economic case for preserving biodiversity for its potential medicinal value. Much medicine “from nature“ comes from domesticated species, ones that can be domesticated, ones that can be cultured or cultivated, or from new creations that are the product of selective breeding and genetic modification. Medicines initially found “in the wild“ are subsequently synthesized. As for the discovery of new compounds, the apparent redundancy of their production by various different species appears to allow that a great extinction is more likely to increase the difficulty of finding them rather than to cause them to be lost entirely. And to extract their medicinal value, the species that remain need only be represented by a few individuals in zoos, aquaria, or seed banks.
Biodiversity is also no safeguard against infectious diseases. This is quite obvious if you consider that humans would lead far healthier life if the large component of biodiversity that consists of pathogens and parasites, vector and reservoirs, were summarily extirpated. In general, biodiversity has no direct bearing on rates of infection:
This range of possibilities provides some better perspective on the notion that the diversity of species is prophylactic medicine. Posed as an unqualified generalization, this proposition is quite categorically false. Mostly, the diversity of species is quite irrelevant to the question of how much disease spreads to humans.
Sometimes more species can reduce human infections. Sometimes more species can increase human infection rates. Whether or not people get infections is determined by conditions and causal chains that either wind up directing pathogens and parasites into human bodies; or not. The “right” conditions for infection can involve more or fewer species. But the number and diversity of species in the causal chain leading up to infection is entirely irrelevant as a causal factor in itself. This is another way of getting back to saying that, in the end, the proposition that biodiversity serves to protect human health is based on a category mistake.
…nor is biodiversity valuable in other ways
It is worth repeating that, according to Maier's analysis, two flagship sources of biodiversity value in the popular imagination (ecosystem services and human health) do not in fact confer value. Simply put, biodiversity comes with significant disservices and negative human health effects. Other candidates for imbuing biodiversity with value also fail to get the job done
:Unspecified moral reasons (section 6.1): Claiming a moral responsibility to protect biodiversity is not an argument for it. There is also a contrary tradition of thought suggesting that human dominion is evidence that all of the Earth’s goods exist for man’s pleasure (equally without supporting argument).
Biodiversity as resource (6.2): Only an extraordinarily small number of species has benefited humanity as resource, and there is little reason to believe this will change in the future. Furthermore, many creatures are destroying resources, think of pests, diseases and parasites. Most devastatingly, there is a great trade-off between biodiversity conservation and agriculture, the latter delivering what is perhaps the most valuable resource of all, food.
Biodiversity as (human) life sustainer (6.4): During the last 3.5 billion years of life on Earth, life has persisted under very different states of biodiversity. Similarly, during humanity’s presence on Earth (since 200,000 years ago), biodiversity has also seen significant transformations (for example the human-driven extinction of larger terrestrial species starting 40,000 to 50,000 years ago). But these transformational changes in biodiversity have not hindered humanity from growing enormously in population, a spectacular flourishing by any purely biological standard.
Biodiversity as progenitor of biophilia (6.6): Apart from the (unresolved) question of whether biophilic tendencies really exist, and whether they constitute an integral part of human flourishing, there is still a wide gap between biophilia and biodiversity. You might enjoy a nice garden, and perhaps watching some animals, but these things are different from biodiversity. There is “no good evidence for a positive correlation between the relaxing role and comfort provided by nature, and wealth of biodiversity” (Froment, 2009).
Biodiversity as Value Generator (6.7): What is claimed by proponents of this view is that biodiversity is valuable because it creates more biodiversity. But this is unconvincing if what is created is not valuable. Furthermore, if interpreted in the sense of creating novelty (that humans can extract value from), novelty may also be not valuable or destructive (e.g. a novel organism making people sick or eating their resources). “Creativity” and “novelty“ are simply not inherently valuable. Novelty is also brought about by mass species extinctions, in the sense of creating room for novel kinds of biodiversity.
Biodiversity as Font of Knowledge (6.8): This view says that more biodiversity means more knowledge, and thus means more value. But not all knowledge is necessarily valuable (what is the value in counting precisely how many pushups an individual lizard performs during its life?). And, similar to the Value Generator view, this one also suffers from the fact that dramatic reductions (or fluctuations) in biodiversity represent rich sources of knowledge. For example, what better way to study previous extinction events than being able to observe one happening now?
Biodiversity as Transformative (6.10): According to this view, biodiversity is valuable because it can change human preferences in systematic ways. The main problem with this view is “the stubborn fact that a person’s preferences might be changed so that she prefers the trivial to the important, the banal to the original, the excessively narrow to the sweepingly full spectrum, and even the bad to the good“. Nor do changes in preferences become valuable by virtue of being systematic.
The Experiential Value of Biodiversity (6.11): According to this view, the experience of biodiversity is valuable because it leads to “good“ transformations (see previous bullet). Maier is skeptical that people (can) directly experience something as abstract as biodiversity in the sense proposed by this view. Maier here sees (again) the recurring error of mistaking the diversity of kinds for the qualities of some particular kinds (or worse, individuals in a particular place). A polar bear or tiger you see or the song of a bird you hear are experiences of those species or individuals, not of biodiversity.
Biodiversity as the Natural Order (6.12): This view, which Maier also refers to as the “just-so model of biodiversity value“, says that biodiversity is valuable only when it is occurring in the appropriate amount. This view has a long philosophical and religious tradition, is closely aligned with the discredited balance of nature theory, and shares with creationism the conception that value is attributed by reference to a particular standard. This standard is typically some (imagined) state of biodiversity in the past from which the world has deviated. This view simply lacks credible reasons
why some particular state of biodiversity is valuable and another is not.
Potential future value also does not favour biodiversity
What about potential future value? In another instructive section (6.9), Maier examines arguments for biodiversity conservation based on option and quasi-option value
grounds. On option value, Maier makes clear that conserving biodiversity for the sake of maybe deriving some benefit from it in the future is a costly gamble that can well be lost (if it turns out that there is no such benefit in the future). More generally, option value, as understood in the economics context, does not have any particular characteristic tendency to favour environmental (or biodiversity) conservation over destruction.Discussions about the costs and benefits of information and irreversibility in the context of quasi-option value (which is supposed to support biodiversity conservation in order to collect more information about its benefits) ignore three uncongenial facts:
Development (not just conservation) can also reveal new and valuable information,
The future can reveal not only potential benefits but also costs and harms from biodiversity, and
Development can yield compound returns, can have unexpected benefits and uncover new opportunities, and is not always possible (but occurs in windows of opportunity that can close, i.e. decisions for conservation can also be "irreversible").
More generally, quasi-option value is a seriously incomplete guide for decision-making, because it offers no answer on when to stop the phase of “waiting and collecting information“ and move into the decision stage. Maier concludes:
It simply won't do to say, with Maclaurin and Sterelny (2008, 154), that “as our knowledge improves… we will come to discover new ways in which species will be valuable.” I can (and, alas, do) say much the same thing about the accumulating junk stored in my garage: If I wait long enough, surely I'll find some use for it. But I recognize that this is but a poor rationalization. It is not a justification for failing to clean out that space and put it to some obviously good use.
Looking towards biodiversity in humanity’s future (7.3), Maier is skeptical of claims that biodiversity losses inflicted by humans alive today will bother our descendants or deprive them of something they will value:
Without any basis for feeling or believing that they have been cheated out of an entitlement, without the loss of anything connected to any experience available to them, and without even the capacity of possible means to acquire a capacity to understand living a human life in a possible world in which they do not happen to live, a shrug of the future shoulders seems both far more likely and far more appropriate than an accusation that we-now acted in a morally reprehensible fashion for our role in creating the world in which they actually live. It is important to emphasize that feelings and beliefs of (at worst) indifference held by future persons regarding the behavior of current persons, will not be grossly inappropriate. They will not be at fault for overlooking some terrible moral misdeeds, as we-now would be if we exhibited indifference to our ancestors’ practice of slavery. On the contrary, their likely charitable attitude towards us and our behavior will be quite reasonable. The norms for their world will be built around the circumstances of human life in that world. These circumstances will be infused by the many goods whose creation was made possible by our-now willingness to forgo (or ignore) any value that would have required a different relationship to the natural world - one in which not all of it were always jealously eyed as the domain of human enterprise and development.
All told, these considerations suggest that persons just a small number of generations from now will thank rather than revile us-now for our willingness to make incursions into the natural world on their behalf. If some of us-now characterize these incursions in terms of destruction, it is only we currently respiring persons who do so. Future persons would not be so inclined. Unable to recognize goods that accrue to living in a world that includes a natural world, they would characterize our behavior in terms of creation - the creation and passing on of the goods that are actually present in their life. Contrary to the claims of those who project the sensibilities of our own time onto the future, future generations would feel an enormous sense of community with us precisely for so assiduously creating the world and circumstances familiar to them and in which they strive to live their life as best as they can.
What do people mean when they say “biodiversity“?
While I find Maier’s key message and arguments mostly very convincing, I have one minor complaint, namely that often when people say “biodiversity”, they don’t really mean how many different species there are, or, more generally, how many different kinds exist within each of multiple biotic and biota-encompassing categories. What people often really mean is a diffuse and sometimes contradictory set of things like the existence of certain individual species or the abundance of a species, or “nature“, or “wilderness“, or other concepts. People arguing in favour of biodiversity might not really care about biodiversity, properly understood. Maybe some are concerned with extinctions of some particular species, but don’t show much interest in the fact that a lot of speciation might be occurring, let alone enthusiasm for active speciation through genetic engineering or assisted migration. So perhaps Maier takes people literally when he shouldn’t. Maier addresses this objection in Chapter 7:
An objection along these lines is so astonishing that it is hard to know how to respond. Fortunately, I believe that a response is safely left to the Pope John Paul II and to E.O. Wilson - both of whom say with unusual clarity that there is a moral imperative to conserve biodiversity. It is safely left to the large cadre of ecologists who have devoted their careers to studying how biodiversity correlates with human goods. It is safely left to the even larger cadre of conservation and restoration biologists who justify their many and varied projects for the good that will accrue to biodiversity. And it is safely left to the world’s major conservation organizations, which portray themselves as biodiversity’s billion-dollar saviors.
A related objection is that Maier has defined biodiversity too narrowly. In fact, Maier’s conception (see figure above) is a very broad umbrella. However, it is careful not to court the triviality of “all that we mean by, and value in, nature“. And yet, people may often court to exactly such trivialities. Maybe even many of the scientists involved.
Or, people may refer with biodiversity only to certain species and only in certain configurations (that are deemed valuable). However, then “biodiversity” is not about diversity:
Of course, one can stipulate that biodiversity comprises just the plants and animals that humans generally like to have around. Ditto for the functions: Any that are perceived not to contribute to such a good as an “ecosystem service“ can be proscribed. Then the value of biodiversity becomes obvious… and tautologous: Biodiversity is good because only good things are allowed to be called “biodiversity“.
This point is at once trivially obvious and hard to keep in mind. The just-so model of biodiversity value (Sect. 5.1.4, The just-so model), in particular, tends to obscure it. This, I believe, is because whatever attraction this model has hinges on its ability to convince us that the value of the status quo is not just positive, but as good as it gets, and what we should be prepared to defend. While evidence and arguments for this position have yet to be produced, it might nonetheless be true. But even if it is true, it must still account for inconvenient kinds - organisms and functions - some of which are, quite literally, scourges of humanity, but nonetheless legitimate parts of the current biodiversity picture.
Having spent 350 pages systematically searching for value in biodiversity without success, Maier devotes the last chapter of the book to his alternative proposal to finding unique value in nature. I will discuss this alternative proposal in a future post, but you can already guess that it will have nothing to do with biodiversity.
Conclusion
“Biodiversity”, first promoted in the 1980s to replace an earlier concern with “wilderness“, features prominently in today’s discussions of environmental impacts and policy.
It is perhaps outstripped in popularity only by climate change. Having read Maier’s excellent book, I shall be more careful in thinking and talking about biodiversity as if it were something valuable (it’s not).And if diversity is not the intended meaning the next time I read or hear “biodiversity”, I will consider that the fallacies, contradictions, irrelevancies, disservices and obstacles to human flourishing Maier identified in biodiversity might also be found in what is the intended meaning. But this is a topic for another day.
My brief summaries do not do justice to Maier's detailed arguments. If you have doubts, read the sections in the book (which I recommend in any case). Note that the core Chapter 6 is open access.
Maier cites a count of 7,000 cultivated crops, representing only about 2% of the estimated 320,000 kinds of plants on Earth. When considering livestock, diversity is less relevant still. Even when (generously) counting breeds instead of species, the resulting number of 7,600 livestock breeds is less than 0.001% of all animal species.
Maier observes that there is much confusion and little shared understanding about the meanings of option- and quasi-option value between different authors, particularly when comparing the economics and conservation literatures.
“Ecosystem health” and “ecosystem integrity” are other highly popular concepts often held as desirable ends of the biodiversity project. But as Maier shows, they are also morally impotent (for starters, an ecosystem cannot have an interest in being healthy).