Natural Kinds & Essences

 
We can ask a simple question about scientific theories. We accept


All ravens are black.


though not


Non-black things are non-ravens.


Why?


They are, after all, logically equivalent.


When we ‘count’ all non-black things and all non-ravens, what are we left with? We are left with black ravens. Thus we arrive back at ‘All ravens are black’. That is why they are equivalent. If something, or anything, is a non-black thing, it can’t be a raven. If anything is a non-raven, then, well, it can’t be a raven. A blue bird is not a raven. A banana (a non-raven) is not a raven.


J.S. Mill believed that the world contains (natural) kinds. We don't compose these kinds. They are there in the world. They are mind-independent. It seems to go against Mill’s empiricism to talk about mind-independence. Perhaps he wouldn’t have used the term ‘mind-independence’ in this context. Perhaps instead he would have talked about his "permanent possibility of sensation" in that if we were to observe a natural kind like a raven, we would observe x, y and z.


What binds a kind together? Its ‘common nature’.


Ravens and other species aren't the only natural kinds. Gold and water are also natural kinds. Though perhaps we should say that H2 O is a natural kind; if ‘water’ refers only to secondary properties or Locke’s ‘nominal essences’. Yes, "we do not create the kind water simply by our classifications" (192). However, we only get to water via our classifications. And if we only get to water via our classifications, then perhaps, in a sense, we do create that natural kind in that we only know it via our classifications and only observe it through our classifications.


Firstly, the ‘nominal essences’ of diamonds. We "pick out diamonds by means of their hardness and transparency" (192). Scientists have no time for these properties. They are not only ‘interest-relative’; but mind- and sense-dependent too. Science discovers what real essences are. Does that automatically mean that such properties will not be ‘interest-relative’ and ‘sense-dependent’? Not according to many philosophers; not least those of whom deny essence altogether.


What is the real essence of diamonds? It is carbon, the very same thing as charcoal.


How can we flesh out this essence of diamonds? By saying that the fact that diamonds are essentially carbon "is another instance of an a posteriori necessary truth" (192) It is necessary that diamonds are carbon. Alternatively, they are carbon at every possible at which they exist. The result of this is that a diamond could lose its "hardness, sheen and transparency – without ceasing to be what it is" (192). Perhaps a diamond wouldn't loose its essence if it lost these contingent’ properties; though but would it still be ‘what it is’? It depends on what it is. And if diamonds are only their essences, then this conclusion follows by definition. Could we still have a diamond without its sheen, transparency, hardness, etc., or would we just have a lump of charcoal? Certainly no layperson would recognise it as a diamond. Why is the layperson’s view of what a diamond is irrelevant? Why are sheen, hardness and transparency irrelevant? Is a lump of charcoal really a lump of diamond?


Natural kinds have become very fashionable in the last, say, fifty years (after a long time of anti-essentialism). Why was this so?


Firstly, "it suggests that science looks for necessary connections" (192). Does this mean necessary connections between natural kinds? Does it mean that that necessary connections between natural kinds are themselves natural kinds? Or does it mean that there are necessary connections between the properties which constitute natural kinds?


Is it really the case that "it is the task of science to discover’ these necessary connections"?


Essences increase the possibility of objectivity in science if we have both natural kinds and necessary connections. In addition, the interest in natural kinds and necessary connections helped "detach it from our observations and attach it to an objective order" (192). Is science really detached from our observations? We know that observations aren’t everything; though surely they account for something – perhaps for much!

Sortal Identity

 
You can't make any judgements about identity, or even self-identity, unless one uses a sortal concept. When someone asks: 


"Is Jack the same as John?"


We must reply:


"The same what? The same banister?" No? The same man? The same person? Yes. The same official? Perhaps not."


Formally, a can be the same F as b; though not the same G. For example, according to Christian doctrine, Christ is the same substance as God the Father; though not the same person. This is not unlike, then, the substance monism of Spinoza. In that case, the substance would be God, and a mode of that substance would be Christ.


This takes us to Leibniz’s law.


This doctrine can be seen to violate this law and transitivity. 


Is everything true of Christ, also true of God?


For example, God Himself was not crucified on the cross. And Christ didn't have the property omniscience (he had the property, after all, of being a man). If Christ is the same substance as God, then if Christ was crucified, then God was crucified.


David Wiggins had his own take on Peter Geach’s thesis:


"Whenever a is the same as b, there must be a sortal concept, under which a and b both fall, which defines their conditions of identity." (147)


So under which sortal concept do both Christ and God fall? Substance? Is substance a sortal concept?


If Gordon Brown is both the Prime Minister and the husband of Mrs Brown, then both the Prime Minister and the husband of Mrs Brown fall under the concept person – they are both the same person.


Is person a sortal concept?


In the case of Gordon Brown, we have an abundance of sortal concepts under which he could fall (if he’s not careful): man, human being, animal, person, biped, earth-dweller, non-raven, etc. Are all these sortal concepts? Well, you can ‘count’ with all these concepts. You can count human beings and persons. You can even count, in theory, all non-ravens.


The non-raven sortal, if it is a sortal, doesn’t make much sense for the reasons given in Hempel’s paradox. However, we can ask which of these sortals is ‘basic’. Perhaps the most inclusive is the most basic. In that case, more things are human beings than are men. Women are not men. But, then, more things are animals than are human beings. Moreover, more things are non-ravens than are animals! Would that mean that Gordon Brown's being a non-raven is more basic or fundamental than his being an animal or a human being? How would we decide such an issue other than by saying that non-raven is a bogus sortal concept because of its infinite application?


Perhaps Aristotle has the solution.


In his ‘theory of being’ he attempted to find "the ultimate constituents of reality". The things which we "must identify if we are to identify anything" (147). Thus we surely don't require the concept [non-raven].


Isn’t the concept [thing], or [object], necessary in order to identify anything – or any thing? Isn't that a circular conclusion?


We don’t need the concept [animal] to identify anything at all. We don’t even need it to identify animals. We can identify animals as objects or things.


What concept, or constituent of reality, is basic or fundamental? Peter Strawson and Donald Davidson, for example, have said that things, objects or persons are fundamental (as well as 'events') – or ‘medium-sized dry objects’. This was an argument against ontological reductionism which cited particulars like sense-data as the fundamental constituents of reality. Or, on a metaphysical reading, simples or atoms as the fundamentals.


What about the sortals we can apply to ‘artificial kinds’? What about the sortal term ‘table’, as applied to tables?


Is table a the same table as table b?


S argues that table "sorts things relative to a human interest, and touches only superficially on the nature of things" (147). We can ask, here, why are human interests ‘superficial’ at all? They aren't superficial to, well, humans! Yes, human beings create tables for specific purposes. Does that make tables superficial? Again, not to us.


Even natural kinds can be seen ‘relative to human interests’.


For example, horses can be seen as good racers or nice pets. Is the sortal term ‘horse’ really that different? If one believes in God, then didn’t God create horses, at least through evolution? Aren’t horses relative to God’s ‘interests’? S describes the difference between ‘table’ and ‘horse’ thus:


"A horse’s history is determined by the laws of equine nature, and without
reference to human interests." (147)


Are science’s classifications unrelated to the interests of scientists and other human beings? Many philosophers argue that they are.


Our classifications can be wrong.


What about the laws of equine nature: are they relative to the interests of scientists? Perhaps not. Though we might have also have got the laws of equine nature wrong. Even if we have got them right, does that automatically mean that the ways in which these laws are determined, described, measured, classified and tested aren't relative to the interests of horse-scientists?


In any case, when we let George the horse fall under the sortal ‘horse’, we also "avail ourselves of a real criterion of identity; we also say what George fundamentally is" (147). Now we know how to identify George as George and as a horse. How does the sortal ‘horse’ in and of itself give us a criterion of identity? It's just a word or a concept. In order to flesh the concept out we would require descriptive information which would bring on board with it other sortal concepts. Though the word ‘horse’ itself wouldn't be a criterion of identity because it only tells us that a horse is a horse. It doesn’t tell us what a horse is. It doesn’t tell us why George is a horse. And so on. When we say that George is a horse, we are saying that this particular horse in front of us is, well, a horse.