Dennett's Genealogy of Modernity: On Spinoza, Hume, Darwin, Turing

In the theory with which we have to deal, Absolute Ignorance is the artificer; so that we may enunciate as the fundamental principle of the whole system, that, IN ORDER TO MAKE A PERFECT AND BEAUTIFUL MACHINE, IT IS NOT REQUISITE TO KNOW HOW TO MAKE IT. This proposition will be found, on careful examination, to express, in condensed form, the essential purport of the Theory, and to express in a few words all Mr. Darwin’s meaning; who, by a strange inversion of reasoning, seems to think Absolute Ignorance fully qualified to take the place of Absolute Wisdom in all the achievements of creative skill. (Beverley 1868); quoted by Dennett.

Dennett quotes Beverley approvingly (although disagreeing with Beverley's own intentions) in his recent From Bacteria to Bach and Back (pp. 53-4). Dennett loves the phrase, 'strange inversion of reasoning' and uses it throughout his book. In fact, one can read his book as a genealogy of modernity because he identifies such a strange inversion of reasoning at the core of Darwin's, Turing's and (historically prior) Hume's thought.

Because Dennett does not offer a definition/explanation of a strange inversion of reasoning, we need some examples to discern what he is up to. First, Here's Dennett's updated version of Darwin's strange inversion of reasoning:

a process with no Intelligent Designer can create intelligent designers who can then design things that permit us to understand how a process with no Intelligent Designer can create intelligent designers who can then design things. (77-78)

Second, here's Dennett's version of Turing's Strange Inversion (in language that pays homage to Beverley):

IN ORDER TO BE A PERFECT AND BEAUTIFUL COMPUTING MACHINE, IT IS NOT REQUISITE TO KNOW WHAT ARITHMETIC IS. (p. 55)

While not denying their many differences,* Dennett treats Turing and Darwin as contributing to a shared insight (third):

all the brilliance and comprehension in the world arises ultimately out of uncomprehending competences compounded over time into ever more competent— and hence comprehending—systems. This is indeed a strange inversion, overthrowing the pre-Darwinian mind-first vision of Creation with a mind-last vision of the eventual evolution of us, intelligent designers at long last." (57-8; emphases in original; Dennett repeats the claim on p. 75.)

The idea of an uncomprehending competence is crucial to Dennett's larger argument, and while i have commented on it before (recall; and here) some other time I'll return to it. But I think now we can give a brief analysis of what Dennett means by a strange inversion of reasoning. It goes something like this.

1. You may think that some basic property X is required for the explanation of observed properties Y.
2. Where X exhibits some intelligence/mindedness/intentionality and Ys typically do not.
3. But in reality properties Y are needed to explain X.

(I leave it to the reader to clean up the argument with due attention to tokens and types!) As I noted the other day, the ur-version of this argument (in modern times), is Spinoza's critique of final causes: "I will add a few remarks, in order to overthrow this doctrine of a final cause utterly. That which is really a cause it considers as an effect, and vice versa: it makes that which is by nature first to be last, and that which is highest and most perfect to be most imperfect." (Ethics, Appendix 1 [not the world's best translation; but good enough today.])

In fact, without having the theory of natural selection, Spinoza does go on to anticipate Darwin's strange inversion of reasoning: "when they survey the frame of the human body, they are amazed; and being ignorant of the causes of so great a work of art, conclude that it has been fashioned, not mechanically, but by divine and supernatural skill, and has been so put together that one part shall not hurt another." (To the best of my knowledge George Eliot, the great novelist and translator of the Ethics, was probably the first to notice the connection which she handles brilliantly in Middlemarch.) With Spinoza safely included we can really call this, indeed, a genealogy of modernity.

So, far so good. Now, here's Dennett's version of Hume's great inversion of reasoning (fourth):

Seeing A, we are wired to expect B, and then when B happens—this is Hume’s master stroke—we misattribute our perceptual reaction to some external cause that we are somehow directly experiencing...In fact, we are succumbing to a benign user-illusion, misinterpreting our fulfilled expectation of an ensuing B as somehow coming from the outer world. This is, as Hume says, a special case of the mind’s “great propensity to spread itself on external objects” (1739, I:xiv) The “customary transition” in our minds is the source of our sense of causation, a quality of “perceptions, not of objects,” and, as he notes, “the contrary notion is so riveted in the mind” that it is hard to dislodge. It survives to this day in the typically unexamined assumption that all perceptual representations must be flowing inbound from outside. (355)

Dennett does not pause to reflect on the fact that it was Hume's defense of the priority of impressions over the ideas corresponding to them which seems the source of the unexamined assumption (that all perceptual representations must be flowing inbound from outside.)+ But I leave that aside here as well as the trickiness of establishing to what degree anything can be 'outside''' in Hume's system.

So, Dennett's version of Hume's version of the strange inversion goes something like this:

• You may think that causal necessity as a basic property of external reality is required for the explanation of observed (tightly conjoined) regularities.
• And so we infer causal necessity from the empirical evidence (via abduction or [in wishful] enumerative induction)
• But in reality it's the mind's properties that explain the sense of necessity we feel when we observe (tightly conjoined) regularities.

While there are family resemblances between this strange inversion and the others above, it really is different in character. These are two good tricks, but not the same trick.

Let me close. I think that this kind of inversion also has a Spinozistic provenance  (even though one of Hume's targets here is  Spinozism). For in the very same appendix to Ethics 1, Spinoza develops an error theory in which "all the explanations commonly given of nature are mere modes of imagining, and do not indicate the true nature of anything, but only the constitution of the imagination." (Notice the wide scope of the claim.)

For quite some time, Bryce Huebner has been insisting that there are great resonances between Dennett's and Spinoza's (and Nietzsche's) philosophy. For glimpses see this important piece. While I often tend to see the differences more than the agreements between Dennett and Spinoza, this post suggests Bryce has been right all along.

*Again, here's Dennett: "There is one big difference between Darwin’s strange inversion and Turing’s. Darwin showed how brilliant designs could be created by cascades of processes lacking all intelligence, but the system for Turing’s cascades of processes was the product of a very intelligent designer, Turing." (58)

+Heré's Hume's example: "where-ever by any accident the faculties, which give rise to any impressions, are obstructed in their operations, as when one is born blind or deaf; not only the impressions are lost, but also their correspondent ideas; so that there never appear in the mind the least traces of either of them." (Treatise 1.1.1.9).