Online research in philosophy

In this paper, I focus on life-threatening medical conditions and argue that from the point of view of natural properties, induction(s), and participation in laws, at least some of the ill organisms dealt with in somatic medicine form natural kinds in the same sense in which the kinds in the exact sciences are thought of as natural. By way of comparing two ‘divisions of nature’, viz., a ‘classical’ exact science kind (gold) and a kind of disease (Graves disease), I show that there is no justifiable ‘ontological gap’ between disease kinds and exact sciences kinds. We have instead a difference of degree.

In this paper I discuss a central objection against diseases being natural kinds—namely, that diseases are processes or transitions and hence they should not be conceptualized in the ‘substantish’ framework of natural kinds. I indicate that the objection hinges on conceiving disease kinds as phase kinds, in contrast to the non-phase, natural kinds of the exact sciences. I focus on somatic diseases and argue, via a representative comparison, that if disease kinds are phase kinds, then exact science kinds are phase kinds as well. On the other hand, if exact science kinds are non-phase kinds, then disease kinds are non-phase kinds as well. This objection should thus be rejected, under a certain caveat, though. If natural kind membership has an influence over the diachronic identity of kind members, then it is possible, in principle, to draw the phase/non-phase distinction such that an ‘ontological gap’ lies between medical kinds and exact science kinds. I show further that this caveat is unavoidable even in relation to substantive universals and ‘essential’ properties—two controversial, strong features that were traditionally associated to natural kinds.

Despite the traditional focus on metaphysical issues in discussions of natural kinds in biology, epistemological considerations are at least as important. By revisiting the debate as to whether taxa are kinds or individuals, I argue that both accounts are metaphysically compatible, but that one or the other approach can be pragmatically preferable depending on the epistemic context. Recent objections against construing species as homeostatic property cluster kinds are also addressed. The second part of the paper broadens the perspective by considering homologues as another example of natural kinds, comparing them with analogues as functionally defined kinds. Given that there are various types of natural kinds, I discuss the different theoretical purposes served by diverse kind concepts, suggesting that there is no clear-cut distinction between natural kinds and other kinds, such as functional kinds. Rather than attempting to offer a unique metaphysical account of ‘natural’ kind, a more fruitful approach consists in the epistemological study of how different natural kind concepts are employed in scientific reasoning.

The vision of natural kinds that is most common in the modern philosophy of biology, particularly with respect to the question whether species and other taxa are natural kinds, is based on a revision of the notion by Mill in A System of Logic. However, there was another conception that Whewell had previously captured well, which taxonomists have always employed, of kinds as being types that need not have necessary and sufficient characters and properties, or essences. These competing views employ different approaches to scientific methodologies: Mill’s class-kinds are not formed by induction but by deduction, while Whewell’s type-kinds are inductive. More recently, phylogenetic kinds (clades, or monophyletic-kinds) are inductively projectible, and escape Mill’s strictures. Mill’s version represents a shift in the notions of kinds from the biological to the physical sciences.

The fact that the names of biological species refer independently of identifying descriptions does not support the view of Ghiselin and Hull that species are individuals. Species may be regarded as natural kinds whose members share an essence which distinguishes them from the members of other species and accounts for the fact that they are reproductively isolated from the members of other species. Because evolutionary theory requires that species be spatiotemporally localized their names cannot occur in scientific laws. If natural kind status is denied to species on this ground, it must also be denied to most classes of concrete entities which are now accorded such status.

Realist accounts of natural kinds rely on an account of causation where the relata of causal relations are real and discrete. These views about natural kinds entail very different accounts of causation. In particular, the necessity of the causal relation given the instantiation of the properties of natural kinds is more robust in the fundamental sciences (e.g. physics and chemistry) than it is in the life sciences (e.g. biology and the medical sciences). In this paper, I wish to argue that there is a difference in kind between the putative natural kinds of the fundamental sciences and those of the life sciences, such that a uniform account of causation cannot capture both. The upshot is that we must either reject the claim that the kinds of the life sciences are genuine natural kinds, or accept that there are different kinds of causal relations involving the relata of natural kinds. I accept the latter. I reject the objection that the true causal relations that relate macro-level kinds are to be found by “going down a level” to causal relation at the fundamental kind, because the relevant causal mechanisms are not at the fundamental level. Since, autonomous mechanistic accounts of causal relations at the macro-level can be provided (e.g. in Biology and medicine), I argue that realism about the natural kinds of the life sciences is justified. I address the problem of negative causation as a counterexample to the positive account of causation that is entailed by realism about natural kinds in the life sciences. I argue that an acceptance of realist accounts of two different kinds of natural kind makes a uniform analysis of causation look unpromising. (277 words).

The aim of this article is to illustrate how a belief in the existence of kinds may be justified for the particular case of natural kinds: particularly noteworthy in this respect is the weight borne by scientific natural kinds (e.g., physical, chemical, and biological kinds) in (i) inductive arguments; (ii) the laws of nature; and (iii) causal explanations. It is argued that biological taxa are properly viewed as kinds as well, despite the fact that they have been by some alleged to be individuals. Since it turns out that the arguments associated with the standard Kripke/Putnam semantics for natural kind terms only establish the non-descriptiveness of natural kind terms and not their rigidity, the door is open to analyze these terms as denoting traditional predicate-extensions. Finally, special issues raised by physical and chemical kinds are considered briefly, in particular impurities, isotopes and the threat of incommensurability.

The thought that diseases form natural kinds tends not to sit well with the essentialist treatment of natural kinds. The essentialist’s candidates for the essences of diseases—etiological properties—rarely satisfy the essentialist’s requirement that they be necessary and sufficient for membership within the kind. Consequently philosophers of medicine have tended to back away from treating diseases as natural kinds. However, this retreat was too hasty: there are good reasons for thinking that diseases form natural kinds. The problem lies with the essentialist treatment of natural kinds, and not with treating disease as forming natural kinds. A similar revolution has taken place within the species debate, where the notion of natural kind has been ‘taken back’ from the essentialist. Borrowing the revised treatment of natural kinds from the philosophers of species and modifying it slightly, I offer a proposed treatment of disease kinds in terms of homeostatic property clusters.

What are biological species? Aristotelians and Lockeans agree that they are natural kinds; but, evolutionary theory shows that neither traditional philosophical approach is truly adequate. Recently, Michael Ghiselin and David Hull have argued that species are individuals. This claim is shown to be against the spirit of much modern biology. It is concluded that species are natural kinds of a sort, and that any 'objectivity' they possess comes from their being at the focus of a consilience of inductions.

Biologists and philosophers of biology typically regard essentialism about speciesas incompatible with modern Darwinian theory. Analytic metaphysicians such asKripke, Putnam and Wiggins, on the other hand, believe that their essentialist thesesare applicable to biological kinds. I explore this tension. I show that standard anti-essentialist considerations only show that species do not have intrinsic essential properties. I argue that while Putnam and Kripke do make assumptions that contradict received biological opinion, their model of natural kinds, suitably modified, is partially applicable to biological species. However, Wiggins'' thesis that organisms belong essentially to their species is untenable, given modern species concepts. I suggest that Putnam''s, Kripke''s and Wiggins'' errors stem from adopting an account of the point of scientific classification which implies that relationally-defined kinds are likely to be of little value, an account which is inapplicable to biology.