| 8153 | By knowing one piece of clay or gold, you know all of clay or gold [Anon (Upan)] |
| 12265 | All water is the same, because of a certain similarity [Aristotle] |
| 19761 | Men started with too few particular names, but later had too few natural kind names [Rousseau] |
| 6939 | What is true of one piece of copper is true of another (unlike brass) [Peirce] |
| 12681 | There are natural kinds of processes [Ellis] |
| 15798 | Kinds are arrangements of dispositions [Fetzer] |
| 6170 | Natural kinds are defined by their real essence, as in gold having atomic number 79 [Rowlands] |
| 6773 | If F is a universal appearing in a natural law, then Fs form a natural kind [Bird] |
| 17478 | Maybe two kinds are the same if there is no change of entropy on isothermal mixing [Hendry] |