Taxonomy and conservation science: interdependent and value-laden

Abstract

The relation between conservation science and taxonomy is typically seen as a simple dependency of the former on the latter. This dependency is assumed to be strictly one-way to avoid normative concerns from conservation science inappropriately affecting the descriptive discipline of taxonomy. In this paper, I argue against this widely assumed standard view on the relation between these two disciplines by highlighting two important roles for conservation scientists in scientific decisions that are part of the internal stages of taxonomy. I show that these roles imply that the two disciplines should be interdependent and that value-judgments should play a substantial role in both.

Introduction

Conservation science is the field of research aimed at evaluating biodiversity loss and developing systematic conservation planning and practices. This field of research is often termed interdisciplinary because it brings together tools and methods of a wide range of disciplines to pursue its aims. One scientific discipline to which conservation science has a particularly close relation is taxonomy, the discipline engaged in the individuation, description and classification of the biodiversity that conservation science aims to conserve.

While the relation of conservation science to disciplines like ecology has been extensively explored, no similar philosophical attention has been devoted to its relation to taxonomy. This might be because this relation seems rather straightforward: conservation science uses the inventory of biodiversity provided by taxonomy to decide which part of this diversity to conserve, and how to do so. This simple view, which is widely adopted by taxonomists and conservationists, entails two characteristics of the relation: first, conservation science is dependent on taxonomy; and second, it is important that this dependency is not two-way to ensure that the normative aspects of conservation science do not inappropriately affect the purely descriptive undertaking of taxonomy.

In a recent controversial contribution to Nature, Garnett and Christidis (2017) challenged these two tenets of the standard view, arguing for a role for conservation scientists and their normative considerations in taxonomy. This was met by strong resistance and nearly universal rejection from taxonomists, who claimed that conservation values should not affect taxonomic outcomes (Raposo et al. 2017; Thomson et al. 2018). Taking this debate as its cue, this paper aims to investigate whether this standard view and its two central tenets are adequate. The outcome will be that they are not. More precisely, I will argue that taxonomy and conservation science should be mutually dependent, and that this interdependency entails a substantial role for values in both disciplines.

I will do this as follows. Section 2 sketches the standard view in more detail. Section 3 argues that recent calls for collaboration between the two disciplines still fall within the boundaries of the standard view. Section 4 then challenges the second tenet (i.e. the dependency is strictly one-way) of the standard view by presenting two ways in which conservation science should play a substantial role in taxonomy. Section 5 considers the implications of this for the role of values in taxonomy and conservation science. Section 6, finally, concludes the paper.

The one-way dependency view

Both taxonomists and conservation scientists frequently make passing remarks about the relation between the two disciplines. From these remarks, a clear image emerges of a one-way dependency relation between the normative discipline of conservation science and the descriptive discipline of taxonomy. This relation is mostly highlighted when it does not meet the requirements of the standard view. In the rest of this section, I discuss such cases to explicate the two main tenets of the standard view.

By far, most discussion about the relation between the two disciplines takes place in the context of the ‘taxonomic impediment’. This term refers to the fact that effective biodiversity conservation is impeded by a lack of reliable taxonomic knowledge. By extension, it has come to refer to the lack of funding, shortage of manpower and low level of scientific prestige that inhibit taxonomists’ efforts of creating such knowledge (e.g. Giangrande 2003). The term thus expresses a direct dependency of conservation science on taxonomy. And indeed, while conservationists operationalize and measure biodiversity in a wide range of ways, the most common of these rely in some way or another on the outcomes of taxonomy (Sarkar 2016). This is most obvious for measures like richness, rarity, or difference, which often use species or higher taxa as units. Similarly, the popular notion of biodiversity hotspot is commonly operationalized in terms of the endemism and richness of species in a particular area (Myers 1988), and measures of phylogenetic diversity directly rely on taxonomic efforts too (Tucker et al. 2017). Moreover, the role of taxonomic information in conservation science is not limited to these measures of biodiversity. It also plays an important role in understanding red-listed species, identifying keystone species, assessing the spatial distribution of species, identifying invasive species and effective conservation of migratory species (Braby and Williams 2016; Khuroo et al. 2007; McNeely 2002).

The importance of these roles is also illustrated by the consequences of bad taxonomy for the efforts of conservation scientists. Duarte et al. (2014) show that efficacy of spatial conservation prioritization is strongly affected by taxonomic uncertainty. Similarly, Romero et al. (2014) show how taxonomic uncertainty can affect distribution forecasting and consequently conservation planning. Finally, consequences of taxonomic instability for conservation planning have been highlighted by Oates and Ting (2015), and further examples of the detrimental impact of bad taxonomy on conservation planning are not hard to come by (e.g. Prie et al. 2012; Vogel Ely et al. 2017).

It is not surprising, then, that Khuroo et al. (2007, p. 257) speak of the relation between the two as an ‘inherent “umbilical” relation’: taxonomy feeds conservation science the knowledge about biodiversity that it requires. It is for this reason that various initiatives have been launched, including the ‘Global Taxonomy Initiative’ by the Convention on Biodiversity, with conservation aims in mind (Secretariat of the Convention on Biological Diversity 2010; Wheeler et al. 2012). All these illustrate the first and uncontroversial tenet of the standard view on the relation between the two disciplines, namely, that it is one of simple dependency: conservation scientists are dependent on taxonomic outcomes to pursue their aims.

While this first tenet is uncontroversial, it is commonly paired with a second tenet that is, I want to argue, far less obvious. Again, this tenet is easiest to explain by looking at cases where it fails to hold. In a controversial editorial in The Economist, it was claimed that taxonomists sometimes recognize groups as species not because their data suggest this, but because this would increase the conservation chances of those groups (Leaders 2007). This practice, the editorial argued, leads to ‘taxonomic inflation’, as existing species are split into smaller groups for conservation purposes. A similar point was made by Karl and Bowen (1999), who showed that the black turtle was retained as a species for political rather than scientific reasons. More recently, Garnett and Christidis (2017) argued that conservationists, legal specialists and policy-makers should be involved in determining criteria for species status. These claims have elicited strong reactions from taxonomists, who argued that this threatens the hypothesis-driven nature and objectivity of taxonomy, and conflates taxonomy with conservation science (e.g. Raposo et al. 2017; Thomson et al. 2018). Their point is that conservation concerns may constitute legitimate reasons in conservation science, but not in taxonomy. Thus, the conservation status of groups of organisms or the strategy for protecting them should not impact taxonomists’ description of these groups.

This reveals the second tenet of the standard view. This tenet holds that concerns from conservation science should not, and generally do not, impact taxonomy. Notice that this is the converse of the first tenet, which holds that the outcomes of taxonomy should influence conservation science. Thus, the dependency between the two disciplines is assumed to be strictly one-way. As suggested by the heated reactions to violations of the second tenet, the one-way character of this dependency is considered of crucial importance. This is because it is connected to what is considered the appropriate role of normative concerns in both disciplines. Taxonomists commonly emphasize that their discipline aims to provide an objective description of evolutionary groups and should be value-free (Raposo et al. 2017; Thomson et al. 2018). Conversely, it is widely agreed that conservation science is a value-laden discipline due to its action-oriented nature (Norton 2008; Sarkar 2008; Soulé 1985). The fear then is that violation of the second tenet could lead to unwanted normative considerations creeping into the descriptive undertaking of taxonomy.

It is worth briefly elaborating on the role of normative concerns, as the relation between the two disciplines in this context is subtler than the previous paragraph may seem to suggest. The precise and appropriate role of normative concerns in conservation science is contested, but it is clear that normative considerations play an important role in the discipline. This does not mean that values are accepted as playing any role whatsoever. While many agree that normative considerations (should) play a role in choosing the constituents of biodiversity and which of these constituents to prioritize, it is also commonly assumed that values should not play a role in choosing surrogates to measure these constituents or in designing the strategy for conserving them (Sarkar 2008, 2016). For example, normative concerns may determine whether biodiversity should be understood as species diversity, but they should not determine which species exist in the first place, and how species-rich a particular area is. Indeed, a role for values in these empirical components of conservation science could even pose a threat to its efficacy (Sarkar and Margules 2002). This is relevant here, as the role of taxonomy in conservation science lies precisely in providing this value-free description. Thus, as long as the dependency-relation between the two disciplines only occurs in the direction assumed by the standard view, taxonomy remains value-free and conservation science is only value-laden in a sense that is considered appropriate. If the relation were two-way, taxonomy would become value-laden, and, consequently, conservation science would be value-laden in a sense that is potentially harmful.

In summary, the standard view consists of two tenets: first, conservation science is dependent on taxonomy; and second, this dependency should be one-way to avoid a value spill-over from conservation science into taxonomy. We saw above that while the first tenet is uncontroversial, the second tenet has recently been questioned. The remainder of this paper evaluates the desirability of this image of taxonomy as a purely descriptive science providing value-free tools to be used by the normative discipline of conservation science. I will argue that it is undesirable, and that we should instead conceive of these disciplines as interdependent and value-laden.

Conservation science in the external stages of taxonomy

One could argue that my representation of the standard view glosses over an important recent trend of growing cooperation between conservation science and taxonomy. This collaboration involves conservation scientists influencing taxonomy in at least four ways: motivating taxonomic research, influencing the representation of taxonomic outcomes, imposing restrictions on taxonomic methods, and influencing the choice of research organisms. This section discusses these influences and argues that they still fall within the standard view as described in the previous section. This paves the way for my arguments for a more substantial role for conservation science in taxonomy in Sect. 4.

The first and most obvious way in which conservation science influences taxonomy is by providing a strong motivation to engage in taxonomic research. Conservation scientists require a reliable inventory of taxa to document biodiversity loss and design conservation action. In this manner, conservation science provides direct motivation for taxonomic research (e.g. Braby and Williams 2016; Wheeler et al. 2012). This motivation is also partly financial, as much of the funding for taxonomy is justified by conservation concerns. Going a step further, some even argue that taxonomists have an obligation to generate reliable and useful knowledge due to the dire consequences of continued biodiversity loss (Vane-Wright 1996). Thus, far from being independent and value-free, taxonomy is affected by conservation science in the shape of motives for research. This is also reflected in taxonomic papers, which often start by discussing conservation concerns or conclude with a section dedicated to the conservation consequences of their claims.

A second way in which it is already commonly accepted that conservation science should influence taxonomy concerns the representation of the outcomes of taxonomic research. Various authors argue that taxonomists should shape these outcomes to facilitate use by conservation scientists, for example by preparing user-friendly identification systems, making taxonomic information easily and freely accessible through various forms of web-taxonomies or databases, emphasizing initial conservation evaluations in taxonomic papers, preparing field guides and generally accepted species lists, and even training para-taxonomists to aid in conservation work (e.g. Costello et al. 2015; Tsang et al. 2016; Vane-Wright 1996). Such attuning of taxonomic information to its purposes has been documented in the construction of biodiversity databases (Devictor and Bensaude-Vincent 2016) and is an explicit aim of many research projects that involve both taxonomists and conservationists (e.g. Wege et al. 2015). The failure to align the outcomes of taxonomy with the needs of its users is also commonly cited as one of the causes of the taxonomic impediment (e.g. Godfray 2002).

Third, conservation science also affects taxonomy by imposing limits on the methods and research practices of taxonomy. For example, conservationists Waeber et al. (2017) argue that taxonomists should avoid killing organisms for specimen sampling. While this is common practice in taxonomy and lies at the basis of much productive taxonomic work, they argue it cannot be justified given the current biodiversity crisis. This is particularly so, they claim, because recent advances in digital taxonomy could be used to make taxonomy less reliant on specimens.

The final and perhaps most impactful way in which conservation science influences taxonomy lies in the choice of research organisms. With a large proportion of all existing species still awaiting discovery and description, it is clear that taxonomists have to prioritize some taxa over others (Mora et al. 2011). Given that effective conservation of a group requires taxonomic recognition, taxonomists should prioritize those groups that conservation scientists single out as particularly urgent. For example, Wege et al. (2015) argue that taxonomists should facilitate conservation science by prioritizing groups in Western-Australia that are particularly susceptible to mining activities in that area. Similarly, Harvey et al. (2011) argue that taxonomists should prioritize short-range endemic groups, as these groups are by their nature vulnerable to important drivers of biodiversity loss such as habitat loss and climate change. More generally, there is growing understanding that a conservation-driven targeted approach is more effective and realistic than the traditional goal of describing all extant biodiversity (Braby and Williams 2016).

While the previous paragraphs show a clear impact of conservation science on taxonomy, I argue that this does not contradict the standard one-way dependency view. This is because the motivations for taxonomic research, the choice of research organisms, limits on specimen sampling and the particular shape in which taxonomic outcomes are represented do not seem to affect taxonomy in any substantial way. One way of putting this is by means of the common distinction between the external and internal stages of science (Douglas 2000). The latter, which are sometimes called the inferential stages, comprise the evaluation and interpretation of data, any inferences made on the basis of these data, and the acceptance and rejection of hypotheses. The former include all remaining scientific decisions, such as motivations for research, selecting a research subject, applying the outcomes of research in practice, or ethical restrictions on methodological choices. The point then is that while the four cases described above show that conservation science impacts the external stages of taxonomy, there is no reason to think they also impact the internal stages of taxonomy. Hence, if the impact of conservation science on taxonomy remains limited to these four ways, it remains a one-way relation: taxonomy impacts the internal stages of conservation science but conservation science does not affect the internal stages of taxonomy. This way, the recent pleas for more cooperation between taxonomists and conservationists still take place within the boundaries of the standard view.

The distinction between the internal and external stages of taxonomy helps to explain why taxonomists and conservation scientists welcome the above described role of conservation science in taxonomy but reject any influence of conservation science on what counts as a species. Unlike the four roles described in this section, such a role for conservation science would be part of the internal stages of taxonomy. This also shows what is needed to challenge the standard view, namely, a legitimate role of conservation science in the characterization of data, the interpretation of data, and the acceptance or rejection of taxonomic hypotheses. I turn to this in the next section.

Conservation science and the internal stages of taxonomy

The previous sections have presented the standard view and argued that recent calls for cooperation between conservation scientists and taxonomists fit within this view. This section claims that conservation science should play a more substantial role in taxonomy and offers two arguments (Sects. 4.1, 4.2) in support of this claim. Together, these arguments put pressure on the standard view and show that the relation between the two disciplines should be one of interdependency.

Unforced ontological choices

To explain the first argument for a role for conservation scientists in taxonomic decisions, it is helpful to return to Garnett and Christidis’ (2017) argument for the regulation of taxonomy. They argue that taxonomy is in a state of disorder due to a lack of consensus on how to define and operationalize ‘species’. While there is broad agreement that species are independently evolving lineages, there is great variety in the way biologists operationalize this notion using different evidence types, methods of analysis, and criteria for species status. Importantly, these different operationalizations yield substantially different outcomes. The result is a state of taxonomic anarchy in which ‘“[s]pecies” are often created or dismissed arbitrarily, according to the individual taxonomist’s adherence to one of at least 30 definitions’ (Garnett and Christidis 2017, p. 25).

There is widespread agreement that the problem of taxonomic disorder needs urgent attention. There is far less agreement about what a solution should look like. Garnett and Christidis propose to fix criteria for species-status and bring species classification under the governance of a centralized body, namely, the International Union of Biological Sciences. This body could draw together the points of view of all relevant stakeholders, including taxonomists and conservationists, and fix the criteria for species delimitation in a way that ensures that the resulting classifications are fit for their various purposes. While perhaps administratively complex, this would put a check on the heterogeneity of groups recognized as species and ensure a form of unification and comparability urgently needed by users of taxonomy.

Similar practices in other fields, like the successful regulation of virus classification (Adams et al. 2017) or the use of consensus conferences in medicine (Solomon, 2015), suggest that this solution is worth considering. Nevertheless, Garnett and Christidis’ proposal met with much resistance from taxonomists (Raposo et al. 2017; Thomson et al. 2018). While evaluating their objections or defending Garnett and Christidis’ proposal is beyond the scope of this paper (see Conix 2019 for this), there is one step in their argument that appears solid and deserves highlighting here. They argue, as many other biologists have before them (e.g. Hey and Pinho 2012; Zachos 2018), that species delimitation is sometimes partially arbitrary. This is because differences between organic groups are often continuous rather than discrete and any precise cut-off point is hard to defend on solely empirical grounds. This arbitrariness is further exacerbated by the fact that groups can evolve independently in a variety of diverging ways. A similar claim has been made by species pluralists in the philosophy of biology (e.g. Kitcher 1984; Dupré 1993; Ereshefsky 2001), who argue that there are multiple ways of carving up the organic world that all pick out relevant but different kinds of groups. The upshot of all this is that taxonomists sometimes have to choose which of many kinds of groups or features to consider relevant for classification. This means that species delimitation sometimes takes place in a grey zone where, on taxonomic grounds, multiple options are legitimate. It follows that species delimitation requires taxonomists to make classificatory choices that are not fully determined by species ontology.

These unforced ontological choices point to a straightforward role for conservation scientists in taxonomy. Given that empirical data gathered by taxonomists do not fully determine which of several groups to recognize as a species, taxonomists have no choice but to rely on other concerns to bridge this gap. Conservation science is an obvious discipline to turn to, as the outcomes of taxonomy play a crucial role in this discipline. The idea is that conservation scientists should cooperate with taxonomists to settle the ontologically underdetermined decisions in a way that makes the outcomes of taxonomy most useful for conservation science. While this argument is controversial, conservation scientists have illustrated how this could work in practice. For example, Frankham et al. (2012) argue that we should use the Biological Species Concept (BSC) rather than the Phylogenetic Species Concept (PSC) to minimize the chances of inbreeding depression in conservation management. Similarly, and in reaction to this, Russello and Amato (2014) argue that only the PSC is sufficiently operational to serve effectively in conservation science. In both cases, conservationists rely on concerns from conservation biology to make decisions that are not fully determined by taxonomic considerations.

Note that this argument for a role of conservation science in taxonomy fits nicely with the arguments put forth by species pluralists, who argue that different ontologically good species classifications are simply fit for different purposes. Dupré (2002, 31), for example, writes that ‘relative to a sufficiently well-articulated set of aims of enquiry there may very well be, and often is, a best way of classifying the phenomena within a domain’. In other words, conservation science and its aims constitute the purposes necessary to move from a plurality of good classifications to a single accepted species classification. However, one could object that species pluralism also suggests a way for taxonomy to avoid this influence of conservation science: taxonomists could simply construct multiple classifications from which various users of taxonomy could then select what is most appropriate for their particular purposes.Footnote 1 However, this is not feasible. For one, taxonomy already lacks time and funding to construct a single species classification; coming up with separate classifications for over thirty distinct species concepts would not be an attainable goal. Moreover, there are typically multiple ways of operationalizing any one species concept, which often result in different classifications (Conix 2018). Thus, recognizing more than one classification would not eradicate the problem of unforced ontological choices.

Epistemological underdetermination

The second argument for a substantial role for conservation science in the internal stages of taxonomy also relies on choices in species delimitation that are not fully determined by taxonomic considerations. However, the underdetermination here is epistemological: conservation science should play a role in resolving uncertainty in taxonomic decisions.

The argument stems from the enormous complexity of the organic world and the evolutionary processes that shape it. Taxonomists gather data to reconstruct these processes and understand the structure of evolutionary groups and their relations to each other. The rising availability and decreasing costs of new molecular methods over the past decades have revealed that this complexity is even greater than previously suspected, with processes such as lateral gene transfer, introgression, hybridization, incomplete lineage sorting and natural selection leading to a network of relations between genes, organisms and groups that is hard to capture in a single classification (Haber 2012). Thus, even the most sophisticated methods of species delimitation cannot easily shed light on all aspects of the organic world relevant to species classification. Moreover, these methods cannot always be used as they are often expensive and time consuming. This means that while we can decrease uncertainty in species delimitation, it is ultimately inevitable. This uncertainty is further exacerbated by the fact that taxonomists have only discovered and described a relatively small proportion of all existing species (Mora et al. 2011). Consequently, taxonomists are not at liberty to collect as much data as they might want to and have to delimit species with substantial margins of uncertainty.

This inevitable uncertainty points to a second role conservation scientists should play in taxonomy. Broadly put, this role lies in choosing between various options that are epistemically equally acceptable. For example, there is an epistemic trade-off between the depth and speed of species delimitation. On the one hand, one might want to gather more data and do more research in order to have greater certainty in species delimitation; on the other hand, one might be willing to allow more uncertainty in exchange for describing species at a faster rate. Both options would add to the body of taxonomic knowledge in different but valuable ways. Thus, purely taxonomic considerations do not seem to determine how this trade-off should be managed. The point is that conservation scientists could step into push this decision in the direction most useful for their discipline. Such a role for conservation scientists in taxonomy is illustrated by proponents of DNA barcoding. While acknowledging the limitations of barcoding for species delimitation, they point out that the gain in speed and efficiency of this method could relieve the taxonomic impediment that currently hampers many users of taxonomic outcomes (e.g. Waugh 2007).

Another example comes from competing methodological standards for integrative taxonomy, which is an approach to species delimitation that relies on multiple independent methods to individuate species. Some argue that integrative research should only recognize a species if it is supported by all the different methods consulted (e.g. Alström et al. 2008), while others argue that species can be recognized even if different methods disagree (Padial and De La Riva 2010; Schlick-Steiner et al. 2010). This disagreement is one between different ways of making the trade-off between false positives and false negatives: requiring full agreement of evidence minimizes the chance of false positives, while recognizing species even if some of the evidence diverges minimizes false negatives. Again, taxonomic concerns do not determine how this trade-off should be negotiated. This leaves space for conservation scientists to weigh in on these decisions and push them in the direction most useful for their work.

Conservation science to bridge the gap

I have argued that conservation scientists should determine taxonomic decisions that are not fully forced by the evidence and species ontology.Footnote 2 Given that these decisions impact taxonomic inferences and can even determine what counts as a species, they clearly play a role in the internal stages of taxonomy. If these arguments hold, the relation between taxonomy and conservation science should be one of interdependency, rather than the one-way dependency of conservation science on taxonomy that is usually assumed.

Before discussing this role for conservation science more extensively in the next section, two remarks are in place here. First, as conservation science is not the only user of taxonomic outcomes, one might argue that the aims and needs of other users (e.g. ecology, trade-regulation, macro-evolutionary studies) should be taken into account too. While this is true, there are at least two good reasons to give conservation science an important place among these users. For one, a large part of the funding that taxonomy receives comes from initiatives connected to biodiversity conservation. While the source of funding should not determine the outcome of taxonomic research, it does justify a prominent place for conservation scientists’ concerns if there are multiple interests pushing underdetermined decisions in different directions. Conversely, taxonomic research geared towards effective biodiversity conservation is also likely to gather more funding from conservation initiatives, thus relieving the taxonomic impediment. A more important reason to prioritize conservation scientists’ concerns in settling underdetermined decisions is that their aim to mitigate the ongoing mass-extinction is generally recognized to be particularly pressing. In other words, the sheer importance of biodiversity conservation justifies putting the needs conservationists high among those that could legitimately influence taxonomy.

A second point worth noting is that this argument by no means entails that taxonomic classification is fully arbitrary, or that conservation science needs to influence all taxonomic decisions. The world heavily constrains which groups can legitimately be called species, and sometimes the decision may be straightforward on purely taxonomic grounds. Thus, admitting a role for conservation science does not rid taxonomy of its empirical and descriptive nature. In this context, it is worth noting that even if it is a rigorous empirical discipline, taxonomists themselves frequently acknowledge that subjective decisions inevitably play a role in their work (e.g. Prie et al. 2012; Schlick-Steiner et al. 2010). Indeed, as discussed in the introduction, some even argue that conservation concerns already impact taxonomists’ choices. The real point of the argument then is that while these underdetermined decisions are currently implicitly determined by pragmatic factors, biases, traditions of research or simply personal preferences (Isaac et al. 2004; Karl and Bowen 1999), they should be settled by the informed judgment of conservation science. In addition to gearing species delimitation towards its most important users, this would have the benefit of transparency about the factors that impact taxonomic decisions and implementation of these factors on a more principled basis.

Values and the role of conservation science

The previous section has revealed a role for conservation scientists in taxonomy. To end the paper, this section discusses this role and investigates its implications for the way value-judgments should play a role in both taxonomy and conservation science.

The role of conservation science proposed here lies in informing decisions that are not fully determined by species ontology and available taxonomic evidence. This explains why conservation scientists are in a good position to determine these decisions: as a goal-driven discipline, conservation science has both an epistemic and a normative character. This normative character is precisely what is needed to determine decisions that cannot be decided by epistemic concerns only. This is because even if there are no epistemic concerns to push a decision either way, it may well be that one is normatively better. For example, while both the BSC and the PSC pick out real biological groups, it may be that one of these is more useful given a particular set of conservation values and aims.

In this context, it is worth pointing out that the two arguments in Sect. 4 have close analogues in the philosophical debate about values in science. Similar to the argument from epistemological underdetermination in this paper (Sect. 4.2), various authors have argued that scientists should rely on value-judgments to resolve uncertainty in science. Most famously, Douglas (2000) argues that value-judgments are needed to determine the appropriate trade-off between false positives and false negatives whenever this decision has potential non-epistemic consequences. More generally, Steel (2010) argues that scientists should rely on values whenever there is a choice between competing options that are equally well-supported by the evidence. Similar to the argument from unforced ontological choices in this paper (Sect. 4.1), David Ludwig (2016) argues that scientists should rely on non-epistemic value-judgments to choose between viable but competing scientific ontologies. Dupré (1993) makes a similar point when he argues that the choice of a classification is relative to the practical or epistemic purposes of that classification. Finally, and particularly relevant to the topic of this paper, Frank (2016) argues that the definition and operationalization of the concept of biodiversity should depend on the particular epistemic and non-epistemic aims of the context in which it is used. This paper has elaborated on the particular way these arguments apply in taxonomy and how they necessitate the collaboration between taxonomists and conservation scientists to address the normative issues they imply.

That is not to say that conservation science’s role is simply to provide value-judgments to bridge the gap of underdetermination. Indeed, it is not clear whether conservation scientists, rather than the local community or society as a whole, are the ones that should decide which values or aims to pursue. Instead, the role of conservation scientists lies in informing the selection of norms and their implementation in taxonomy. Conservation science is in a good position to do this because it combines expertise in the study of the organic world with expertise in issues concerning science governance, policy making, collective decision making, the integration and interpretation of local cultural norms, and settling trade-offs between multiple goals. This combination of biological expertise and experience in answering normative questions is precisely what is needed in deciding which of many viable taxonomic classifications should be preferred, and which particular way of balancing various epistemic standards is most effective. As pointed out above, it may be that our conservation aims are better served by one species concept compared to another in the existing framework of conservation initiatives and legislation. Similarly, it may be that the best strategy to address the biodiversity crisis requires taxonomists to classify species faster at the expense of reliability. The point is that, given their expertise, conservation scientists are in a better position than taxonomists to answer these questions.

To illustrate this point, it is helpful to go back to the arguments of Frankham et al. (2012), a group of conservation geneticists commenting on the taxonomic choice between the BSC and the PSC. The former concept recognizes a group as a species if it is mostly reproductively isolated, while the latter only requires that a group is diagnosable. Since reproductively isolated groups often consist of multiple diagnosable groups, the PSC tends to split groups that would be lumped in a single species by the BSC. Frankham et al. point out that the habitats of many species have become fragmented due to human impact on the environment. This has led to many small isolated populations becoming diagnosable through drift in a relatively short time. They argue that effective conservation of such groups often requires crossing them with other populations to avoid inbreeding depression. However, there are often regulatory and legal hurdles to doing this if the groups are recognized as distinct species, which is more likely under the PSC. Thus, it is better to classify species under the BSC because it recognizes these fragmented and sometimes diagnosable groups as a single species. The point here is that these authors resolve the taxonomically underdetermined choice between the BSC and PSC by relying on their insight in conservation genetics, the regulatory context in which conservation takes place, and the normative judgment that certain fragmented populations should be conserved. I argue that it is this empirically informed normative point of view that conservation scientists have to offer for taxonomy.

This specification of the role of conservation science in taxonomy has direct implications for the role that non-epistemic values should play in both disciplines. Most obviously, it points to a role for non-epistemic values in the internal stages of taxonomy. If the arguments presented in this paper hold, then conservation values should be involved in deciding whether a particular group counts as a species. This goes against the standard view, which portrays taxonomy as a purely descriptive discipline that is and should remain independent from the conservation values driving conservation science (Raposo et al. 2017; Thomson et al. 2018). At the same time, the arguments in this paper point to a limit on the role these values can play: conservation values can play a role in the external stages of taxonomy and should be used to make unforced ontological and epistemological choices, but there is no reason to assume they play any role beyond that. More precisely, the arguments here do not justify recognizing a group as a species simply because we want it to have a particular conservation status. Thus, the arguments here do not justify the practices of wishful thinking flagged in the Economist editorial (Leaders 2007) discussed above.Footnote 3

The arguments in this paper also point to a role for values in conservation science that adds to what is currently accepted in the literature. First, it has been suggested that the notion of biodiversity can be operationalized in a value-free manner by equating it with theoretical notions that seem value-free, such as species richness (Frank 2014). According to this argument, values may be needed to decide whether species richness ought to be maximized, but they should not play a role in measuring richness in the first place. The arguments in this paper show that in so far as these non-normative approaches rely on outcomes of taxonomy, they are not fully value-free. This points to a role for values in conservation science, as I have argued that conservation scientists should play a role in settling the value-laden decisions involved in creating these measures. Second, the arguments here also suggest a role that dovetails with and adds to the normative view defended by Sarkar (2008). Sarkar argues that while values should be involved in choosing the constituents of biodiversity, they should not influence the choice of surrogates to operationalize these constituents. The arguments in this paper have shown that this is impossible whenever these surrogates depend on the outcomes of taxonomy. This is because choosing any specification of such surrogates requires the value-judgments involved in taxonomic classification.

Finally, it is worth mentioning that the arguments in this paper constitute an indirect argument against views such as Morar et al.’s (2015), which proposes to eliminate the notion of biodiversity from conservation science because it tacitly imports value-judgments under the guise of what appears to be an objective notion (see also Frank 2016). I have shown that even if the notion of biodiversity were to be eliminated, value-judgments would still enter in a similar way through species classifications used for measures of biodiversity. More generally, my arguments are particularly damning for Morar et al.’s hopes of moving the burden for value-laden decisions away from scientists and onto policy makers, as it is beyond doubt that the value-laden outcomes of taxonomy play a crucial and ineliminable role in conservation science and, consequently, are themselves not vulnerable to eliminativist arguments. This suggests that rather than trying to move value-laden decisions away from practicing scientists, those scientists should be explicit about the non-epistemic factors that influence their decisions.

Conclusions

This paper has argued that, contrary to the standard view that is generally assumed, conservation science and taxonomy should be mutually dependent. The former relies on the latter for an inventory of biodiversity, and the latter should rely on the former for resolving unforced decisions in the construction of this inventory. As these unforced decisions should be resolved by research that is both empirical and value-laden, this relation of mutual dependency implies a role for values in both conservation science and taxonomy.

To end the paper, it is worth noting that while the view defended here challenges the standard view, it is not original. As noted in the introduction, Garnett and Christidis (2017) recently argued for a substantial role for conservationists and legal specialists in fixing the criteria for species delimitation. Similarly, Mace (2004) argues for increased collaboration between taxonomists and conservationists, and for a substantial role of the latter in taxonomic work. Adding to this, this paper has further clarified the relations between the two disciplines and substantiated the rare calls for closer collaboration with philosophical arguments.

Notes

  1. 1.

    I thank an anonymous reviewer for pointing out this objection.

  2. 2.

    Note that while I make a sharp distinction between ontological and epistemological underdetermination, it is often not clear which of these, or both, are at play in practice. As this does not affect my arguments, I make abstraction of this complexity here. I thank an anonymous reviewer for pointing this out.

  3. 3.

    Similar limits are captured in the literature on values in science by Steel’s (2010, 25) notion of ‘nonobstruction of truth’ and Douglas’ (2000) distinction between direct and indirect roles for values in science.

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Acknowledgements

I am grateful to two anonymous reviewers and the editor for their careful reading and insightful comments. This research was sponsored by the KU Leuven Bijzonder Onderzoeksfonds Grant 3H160214.

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Conix, S. Taxonomy and conservation science: interdependent and value-laden. HPLS 41, 15 (2019). https://doi.org/10.1007/s40656-019-0252-3

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Keywords

  • Taxonomy
  • Conservation science
  • Values in science
  • Species classification