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My latest paper

Science & Education, February 2013Volume 22Issue 2pp 221-240

Biological Essentialism and the Tidal Change of Natural Kinds

  • John S. Wilkins

The vision of natural kinds that is most common in the modern philosophy of biology, particularly with respect to the question whether species and other taxa are natural kinds, is based on a revision of the notion by Mill in A System of Logic. However, there was another conception that Whewell had previously captured well, which taxonomists have always employed, of kinds as being types that need not have necessary and sufficient characters and properties, or essences. These competing views employ different approaches to scientific methodologies: Mill’s class-kinds are not formed by induction but by deduction, while Whewell’s type-kinds are inductive. More recently, phylogenetic kinds (clades, or monophyletic-kinds) are inductively projectible, and escape Mill’s strictures. Mill’s version represents a shift in the notions of kinds from the biological to the physical sciences.


  1. These are tangentially relevant musings, but a blog post consisting of an article abstract arguably invites that.

    A while ago I wondered — and have never got around to asking — about the following. Suppose we use x|y to mean the most recent common ancestor of x and y, and {x} to mean the clade descended from x. So the clade consisting of everything descended from the nearest common ancestor of humans and chocolate would be referred to as {homo|theobroma}. Or {theobroma|homo} if you prefer to put the important genus first.

    Is anything like this done (I know nothing), and is there any point? The obvious use is to avoid privileging certain clades by naming them, but at the cost of having a multitude of synonymous formulations per clade.

    • John Harshman John Harshman

      There is such a convention. A + B is used to mean “the common ancestor of species A and species B and all its descendants”, and A > B is used to mean “all species more closely related to species A than to species B”. Though it isn’t generally used in the way you suggest but as a convenient shorthand way of representing the phylogenetic definition of a group.

      • One reason for not doing what the Dragon suggests is that it would lead to an explosion of names to memorise, which would be constantly revised as phylogenies shift (should we have a name for the LCA of roses and eagles, for example?).

        The convention John mentions is free of that difficulty, since it is clear from context and need not be remembered outside a paper that uses it for a particular purpose.

  2. This paper’s definitely on my to-read list.

  3. Jeb Jeb

    I will have to finish reading the paper tommorow. I got to this bit.

    “and those which resemble them as strongly as they resemble one another.”

    then got distracted and started laughing. The vision will not leave my brain.

    ” An ancient philofopher faid, Man was a “two legged animal without feathers”- upon which his rival Sage had a Cock plucked bare, and fet him down in the fchool before all the difciples, as a Philofophic Man”

    • The story of the plucked rooster is in Diogenes Laërtius, told of Diogenes of Sinope. Plato is reported to have added “with broad nails” to his “featherless biped” definition.

      • Jeb Jeb

        When I look at the depth, contexts and multiple subjects that surround H.O.P, H.O.S. and science itself and contrast the great abyss with my somewhat limited knowledge: I can identify entirely with that small and somewhat startled bird. A somewhat apt mascot.

        • You have just suggested to me the cover of my next book 🙂 A plucked rooster with fingernails.

        • Jeb Jeb

          The paper I promised to write for a journal on humor sprung effortless to life out of last nights laughter and started to take form.

          Pleasing way to start a subject.

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