1. Karl Popper, The Open Society, Chapter 11, section II, is still the best restatement of methodological essentialism and objections to it. The same place also introduces methodological nominalism, in order to block the positivistic existential import (or rather export) which draws ontological conclusions from the nominalist method quite illegitimately. The commonsense of the positivistic reductionism as based on nominalism cum deductivism is counteracted by the seeming commonsense of the new Aristotelian essentialism: the two become intellectual poles as Lévi-Strauss-style myths that think for us. Of course both extremes stretch commonsense too mad, and only mixing them returns us to common sense. Hence we better reject both extremes and have no need to mix them to avoid their unpleasant extremism.
2. See, for example, Baruch Brody, ‘Towards an Aristotelean Theory of Scientific Explanation’, Philosophy of Science 39 (1972), pp. 20–31, reprinted in E. D. Klemke et al. (eds.) Introductory Readings in the Philosophy of Science (Prometheus Books, Buffalo, N.Y., 1980), pp. 112–23, where the difficulty is noted.
3. See my ‘Naming and Necessity: A Second Look’, Iyyun 44 (1995), pp. 243–272.