| 8153 | By knowing one piece of clay or gold, you know all of clay or gold [Anon (Upan)] |
| Full Idea: By knowing one lump of clay, all things made of clay are known; by knowing a nugget of gold, all things made of gold are known. | |
| From: Anon (Upan) (The Upanishads [c.950 BCE], 'Chandogya') | |
| A reaction: I can't think of a better basic definition of a natural kind. There is an inductive assumption, of course, which hits trouble when you meet fool's gold, or two different sorts of jade. But the concept of a natural kind is no more than this. |
| 12265 | All water is the same, because of a certain similarity [Aristotle] |
| Full Idea: Any water is said to be specifically the same as any other water because it has a certain similarity to it. | |
| From: Aristotle (Topics [c.331 BCE], 103a20) | |
| A reaction: (Cf. Idea 8153) It take this to be the hallmark of a natural kind, and we should not lose sight of it in the midst of discussions about rigid designation and essential identity. Tigers are only a natural kind insofar as they are indistinguishable. |
| 19761 | Men started with too few particular names, but later had too few natural kind names [Rousseau] |
| Full Idea: Men at first unduly multiplied the names of individual things, owing to their failure to know the genera and species, but later made too few genera and species, owing to their failure to have considered beings in all their differences. | |
| From: Jean-Jacques Rousseau (Discourse on the Origin of Inequality [1754], Part I) | |
| A reaction: The fact that two leopards differ is not a good enough reason to assign them to two different general terms. Adjectives can do all the necessary modification. The single general term acknowledges something important. |
| 6939 | What is true of one piece of copper is true of another (unlike brass) [Peirce] |
| Full Idea: The guiding principle is that what is true of one piece of copper is true of another; such a guiding principle with regard to copper would be much safer than with regard to many other substances - brass, for example. | |
| From: Charles Sanders Peirce (The Fixation of Belief [1877], p. 8) | |
| A reaction: Peirce is so beautifully simple and sensible. This gives the essential notion of a natural kind, and is a key notion in our whole understanding of physical reality. |
| 12681 | There are natural kinds of processes [Ellis] |
| Full Idea: There are natural kinds of processes. | |
| From: Brian Ellis (The Metaphysics of Scientific Realism [2009], 3) | |
| A reaction: Interesting. I am tempted by the view that processes are the most basic feature of reality, since I think of the mind as a process, and quantum reality seems more like processes than like objects. |
| 15798 | Kinds are arrangements of dispositions [Fetzer] |
| Full Idea: Kinds of things are specific arrangements of dispositions. | |
| From: J.H. Fetzer (A World of Dispositions [1977], 2) | |
| A reaction: A 'disposition' doesn't seem quite the right word for what is basic to the physical world, though Harré and Madden make a good case for the 'fields' of physic being understood in that way. I prefer 'power', though that doesn't solve anything. |
| 6170 | Natural kinds are defined by their real essence, as in gold having atomic number 79 [Rowlands] |
| Full Idea: Part of what it means to be a natural kind is that they are defined by a real essence, a constitution that marks them out as the substance they are (as water is essentially H2O, and gold essentially has atomic number 79). | |
| From: Mark Rowlands (Externalism [2003], Ch.6) | |
| A reaction: A 'real essence' would be the opposite of a 'conventional essence', which is just a human way of seeing things. |
| 6773 | If F is a universal appearing in a natural law, then Fs form a natural kind [Bird] |
| Full Idea: The proposal is that if F is a universal appearing in some natural law, then Fs form a natural kind. | |
| From: Alexander Bird (Philosophy of Science [1998], Ch.3) | |
| A reaction: Such proposals always invite the question 'What is it about F that enables it to be a universal in a natural law?' Nothing can be ultimately defined simply by its role. The character (essence, even) of the thing makes the role possible. |
| 17478 | Maybe two kinds are the same if there is no change of entropy on isothermal mixing [Hendry] |
| Full Idea: One suggestion is that any two different substance, however alike, exhibit a positive entropy change on mixing. So absence of entropy change on isothermal mixing provides a criterion of sameness of kind. | |
| From: Robin F. Hendry (Chemistry [2008], 'Micro') | |
| A reaction: [He cites Paul Needham 2000] This sounds nice, because at a more amateur level we can say that stuff is the same if mixing two samples of it produces no difference. I call it the Upanishads Test. |