1) Kornblith’s natural kinds are constituted by unobservable properties. This seems to have been critiqued as a return to Platonic ideals, or some kind of out-dated metaphysics, though I do not see this notion of unobservables in this light. If an unobservable is a homeostatic cluster, a gene, a chemical compound, a DNA strand, then it is induced by science to be of the physical world (metaphysics – what is the world that we may know it – in philosophy). If evolution is intoriduced to the argument, these are definitely not ideals as they are in a state of change and relationship to the environment. This is foremost a metaphysical theory (though, if it is a theory that purports to describe things in the world that can be empirically observed and tested, is it not a physical theory??)
2) There are real kinds in nature, Locke’s real essences.
3) Epistemology: this all relates to using induction to justify belief. However, always watch for using induction to justify induction. If Kornblith uses IBE about the success of science to justify induction, and IBE is a form of induction, is there a circular problem developing? I would argue that this does not need to be defined as circular, but rather that inferential inductive arguments are satisfactory so long as they are successful, as they have been thus far, until such a time as they are unsuccessful. You could take Thomas Kuhn’s paradigm shifts as a model for mapping this out. Also, watch for a priori arguments. IBE is comparative. It looks at alternative explanations, determining the best explanation for the given data. This can be used to frame the ‘satisfactory’ comment: once the data changes i.e. science is unsuccessful, induction can be argued as unjustified. However, the character of science, defined as Popper and Kuhn might put it, that it seeks to best explain the given data (explanatory, risky conjectures and refutations, and paradigmatic), science becoming ‘unsuccessful’ is highly unlikely.
4) Natural kinds and their apparent existence in the world show that inductive inference is reliable. Natural kinds can be argued for via Richard Boyd’s Homeostatic Property Cluster (HPC) account of natural kinds. The real kind structure of nature is what underlies the reliability of inductive inference. HPC is not committed to the existence of a single correct classificatory system in each scientific domain.
5) updating Locke: Locke assumed that Natural Kinds had to have all properties in common. Kornblith (in light of science) asserts that some properties are essential to natural kinds, others are non-essential, and members of natural kinds need only share the essential (HPC). Locke assumed that we couldn’t discover real essences. The advance of science has allows us now to discover ‘unobservables’. Given the success of science, or nominal kind classifications reflect real differences in kind found in nature.
6) Philosophy of science: realism vs. anti-realism. Kornblith’s argument for real kinds and the success of science reflect a traditional argument for scientific realism. Success of science is measured by empirical, explanatory, technological successes. The best explanation for this success is that scientific theories are (approximately) true and the entities they posit exist. This is IBE of an observed fact: success of science.
7) Kornblith’s view of Natural Kinds asserts that there are real divisions in nature. This runs counter to Locke who asserts that there are no chasms or gaps in nature.
8) Reductionism: special sciences reduce to physics and/or chemistry. Kornblith rejects this. Biological kinds may be composed of physical stuff, but biological kinds do not reduce to chemical or physical kinds. This seems anti-intuitive to me. I would have thought that a biological kind i.e. a reptile, would at some point reduce to a chemical kind i.e. DNA chemical makeup unique to reptiles. From Kornblith:
“Consider a particular dog, Fido. Fido is entirely physically composed … Nevertheless, even if we were to have an atom by atom description of Fido at this moment, Fido could not be identified with this collection of atoms. If we were to remove a single atom from the collection, we would not have the same collection; but we would, in all likelihood, still have the same dog.” (K, p 54 – 55)
But what if a change was made at the DNA level, at the time of conception and development of fetus, a change could be significant enough to entirely remove Fido from his natural kind grouping. So perhaps at the level of the atom kinds are indistinguishable, i.e. atoms are all alike, but at the chemical level kinds are entirely distinguishable.
Also, the question arises, am I identifiable with the matter that makes me up? Alternatively, how significant is the loss of particles and atoms in dry skin, or when I cut myself and lose blood? Do I really lose a part of myself? So perhaps there is a difference between the atoms that constitute the matter that you are, and the process of formation at the beginning, in DNA or whatever else, that determines what you are, what hair color you will have or deformities or eye color. I would have to argue that I am identical with the DNA blueprint that constitutes my physical makeup; it gives me my blue eyes, my brown hair, my height, my general physique. In this sense I argue for reductionism. But, am I identical with the atoms that come together to constitute the matter that holds me together? No. There is a temporal factor to this reductionism to do with conception and evolution.
Also, natural kinds is not about individual entities, it is about groupings.