The belief that species were immutable productions was almost unavoidable as long as the history of the world was thought to be of short duration; and now that we have acquired some idea of the lapse of time, we are too apt to assume, without proof, that the geological record is so perfect that it would have afforded us plain evidence of the mutation of species, if they had undergone mutation.
But the chief cause of our natural unwillingness to admit that one species has given birth to other and distinct species, is that we are always slow in admitting any great change of which we do not see the intermediate steps. The difficulty is the same as that felt by so many geologists, when Lyell first insisted that long lines of inland cliffs had been formed, and great valleys excavated, by the slow action of the coast-waves. The mind cannot possibly grasp the full meaning of the term of a hundred million years; it cannot add up and perceive the full effects of many slight variations, accumulated during an almost infinite number of generations.
Although I am fully convinced of the truth of the views given in this volume under the form of an abstract, I by no means expect to convince experienced naturalists whose minds are stocked with a multitude of facts all viewed, during a long course of years, from a point of view directly opposite to mine. It is so easy to hide our ignorance under such expressions as the `plan of creation,' `unity of design,' &c., and to think that we give an explanation when we only restate a fact. Any one whose disposition leads him to attach more weight to unexplained difficulties than to the explanation of a certain number of facts will certainly reject my theory. A few naturalists, endowed with much flexibility of mind, and who have already begun to doubt on the immutability of species, may be influenced by this volume; but I look with confidence to the future, to young and rising naturalists, who will be able to view both sides of the question with impartiality. Whoever is led to believe that species are mutable will do good service by conscientiously expressing his conviction; for only thus can the load of prejudice by which this subject is overwhelmed be removed.--Charles Darwin The Origin of Species, Chapter 14.
Yesterday (recall), I remarked that Darwin likes to bookend/frame his arguments in terms of the ignorance of savages (recall also here). In later editions (from the third onward) of Origin this is accompanied by a further framing: in An Historical Sketch, Darwin gives an informed (albeit potted) history of the "progress of opinion on the origin of species" leading up to "the publication of the edition of the work." The book closes with a kind "prophetic glance into futurity"* in which Darwin sketches a trajectory for the reception of his book which I have quoted above. Of course, the rhetorical point of both (the historical sketch) and the quoted passage above is to promote and influence the uptake of Darwin's theory (and, perhaps, to reward him with proper credit for the relevant bits of it).
Ever since the work of D.T. Campbell (on 'evolutionary epistemology' a term coined by him in Popper's (1974) Schilpp volume) and David Hull (with his evolutionary approach to development of Science) the idea of applying evolutionary ideas to knowledge has been thoroughly worked out and covers many different kinds of projects. The SEP article by Bradie and Harms suggests that Dewey and the pragmatists were the first to to do so. But I am convinced that evolutionary ideas about knowledge precede Darwin and may well have influenced the development of his views in biology (that's for another time). Even so, the purpose of the present post is to look at how Darwin conceptualizes the sociology of knowledge.
1. The first sentence above suggests that ideas in biology are influenced by ideas about or dependent on cosmogony/cosmology. That's no surprise because as Darwin is at pains to emphasize, his theory requires an almost unimaginable lengthening of the age of the Earth. For those steeped in Christianity that's a problem; but even among christian deists there was a steady increase in the possible age of the Earth from the seventeenth century onward. Spinozists, of course, had no trouble allowing that the age of the Earth extended backward into infinity (as space was infinite). That is to say, Darwin is acutely aware that the uptake of his ideas about the living world are influenced by what is taken to be possible and reasonable in other domains of inquiry.
2. The second sentence, which restates an important evidential objection against Darwin's theory, reinforces that first point and recalls his ninth chapter which was devoted to refuting the objection. His response there is really three-fold: the geological record has not been exhausted yet; the geological record will always be incomplete (due to constraints on fossilization, and the submersion of previous lands into oceans, etc.); the study of the geological record is itself influenced by the recent "the revolution in our palaeontological ideas." That is, while Darwin is a gradualist about the evolution of species, Darwin conceives of development of disciplinary knowledge as capable of revolutions in thought. I am convinced this idea is indebted to Smith's History of Astronomy.+ Despite the existence of such revolutions, his own 'historical sketch' suggests that there is progress in knowledge. So Darwin is using 'revolution' not in the old-fashioned sense of a circular understanding of knowledge (time, orbits, etc.) but more in the modern sense of a dramatic change, which can (but need not) be an important advance,
Incidentally, as an aside, my mention of Spinozism is not innocent; in that ninth chapter he also writes, "During each of these years, over the whole world, the land and the water has been peopled by hosts of living forms. What an infinite number of generations, which the mind cannot grasp, must have succeeded each other in the long roll of years!" While I am happy to concede to a skeptic that all Darwin needs to be saying here is that there has been a very huge number of generations beyond the mind's possible conception, his use of 'infinite' is politically dangerous--because that implies there need not have been a start at all.** This infinity is repeated in the passage quoted above.
3. In the second quoted paragraph Darwin then offers a non-epistemic, but psychological error-theory for why a community of enquirers, may be resistant to the uptake of his theory. He claims it is a psychological fact that we require to see intermediate steps before we grant the existence of a great change. And if those steps are not easily visible, we are "always slow" in admitting any "great change." The psychology here is indebted to Smith's psychological-epistemic account (see my book) of how gaps prevent the mind to go along with any claim (and even generate the painful emotion of wonder--which prompts us to further inquiry). We recoil from such gaps.
4. This is related to a further psychological point which closes the second paragraph: from the vantage point of the minds of individual epistemic agents, the claims made in geology and in Darwin's theory are fundamentally hard if not impossible to grasp. The point is a quirky one, but can be understood if we take the idea of gaps seriously. It is impossible to inspect visually or manually, as it were, each step in an (unfolding) infinite series. Even if we avoid Zeno style paradoxes here, there is simply no time or resources to do so. The would be knower here, has to allow a form of abstraction that jumps over any would be gaps.++
5. Darwin then closes with a now familiar thought (often attributed to Planck -- "A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it --) that scientists who grew up with different conceptual framework are likely to resist to come around to his theory. The epistemic significant point is that Darwin again expresses the idea that background ideas influence the uptake of new theories. In this case the background ideas are deeply entrenched in alternative paradigm.
6. In addition, Darwin points out that there are really two main kinds of stances toward a theory: (i) one can have a disposition" to attach more weight to unexplained difficulties; (ii) and a disposition that attaches more weight "to the explanation of a certain number of facts." The first (i) is a skeptical disposition; the second (ii) is a confirmatory disposition. The interesting point here is that Darwin recognizes that (i) is a legitimate position and that he does not try to argue against it. But it's clear he thinks that this is nonthreatening because such characters may well find even more problems with other theories.
7. Darwin assumes that the community of knowers is populated with epistemic agents that have different epistemic characters. For in addition to (i-ii), it turns out that (iii) flexibility of mind, and (iv) young age (which he claims is correlated with impartiality) may also impact the uptake of new theories. (I don't mean to suggest there can't be hybrids of i-iv for Darwin.) That is, not unlike his theory of plants and animals, Darwin assumes natural variability within epistemic communities.
8. Okay, this is a long-ish blog post now. So, one closing observation. The selection mechanism here, which is a kind of bottleneck, is the mind and its disposition of the epistemic agent. So, it strikes me that Darwin is edging close to a theory of cultural evolution of which his meta-philosophy of science is an example.