It's hard to know the proper attitude to take toward this idea. Daniel Dennett, after all, is a brilliant and much honored thinker. But I can't take the idea seriously. He's running on fumes. The noises he makes are those of engine failure, not forward motion.
At around 53:00 into this video ("Cultural Evolution and the Architecture of Human Minds") he tells us that human culture is the "second great endosymbiotic revolution" in the history of life on earth, and, he assures us, he means the "literally." The first endosymbiotic revolution, of course, was the emergence of eukaryotic cells from the pairwise incorporation of one prokaryote within another. The couple then operated as a single organism and of course reproduced as such.
At 53:13 he informs us:
In other words we are apes with infected brains. Our brains have been invaded by evolving symbionts which have then rearranged our brains, harnessing them to do work that no other brain can do. How did these brilliant invaders do this? Do they reason themselves? No, they're stupid, they're clueless. But they have talents the permit them to redesign human brains and turn them into human minds. [...] Cultural evolution evolved virtual machines which can then be installed on the chaotic hardware of all those neurons.
Dennett is, of course, talking about memes. Apes and memes hooked up and we're the result.
In the case of the eukaryotic revolution the prokaryots that merged had evolved independently and prior to the merging. Did the memes evolve independently and prior to hooking up with us? If so, do we know where and how this happened? Did they come from meme wells in East Africa? Dennett doesn't get around to explaining that in this lecture as he'd run out of time. But I'm not holding my breath until he coughs up an account.
But I'm wondering if he's yet figured out how many memes can dance on the head of a pin.
More seriously, how is it that he's unable to see how silly this is? What is his system of thought like that such thoughts are acceptable?
Earlier in the talk he gives an example that illustrates something I'm finding indicative of the way he thinks about things. The term he uses is "free-floating rationale." He says he doesn't much like it, but as he introduced it some years ago, he's stuck with it.
What does it mean? The example he gives is stotting, or pronking, which the Wikipedia defines as follows:
Stotting (also pronking or pronging) is a behavior of quadrupeds, particularly gazelles, in which they spring into the air, lifting all four feet off the ground simultaneously. Usually, the legs are held in a relatively stiff position and the back may be arched with the head pointing downward. Many explanations of stotting have been proposed; there is evidence that at least in some cases it is an honest signal to predators that the stotting animal is not worth pursuing.
What this honest signal tells predators is that the animal is fit and fast and so is capable of running a predator into the ground. Predators take the signal at face value and don't bother with pursuit.
Dennett's point is that we have absolutely no reason to believe that a stotting animal consciously intends to signal its fitness nor that a predator consciously understands the signal. This signal, and the predator's response, evolved through the standard evolutionary process and no more requires conscious intent than white tails or long sharp teeth.
And that's where Dennett uses his term "free-floating rationale." There is an explanation for why the animal stots, there is a reason, if you will, but the animal is not aware of that reason. Hence it is "free-floating", a free-floating rationale.
Well, I can see why the term makes Dennett antsy and I cannot see why he ever introduced it. Nor can I see why, if it bothers him enough to remark on it, he introduces it in his current run of lectures on cultural evolution (this isn't the first video where I've heard it). The term adds nothing to our understanding of the phenomenon.
All it achieves is a rather peculiar reification. The term itself suggests that if you see a stotting animal and you look real close, you'll see a subtle atmospheric disturbance near the animal, like a bit of hot air coming out of a vent. That's the FFR just fluttering about.
Of course Dennett intends no such thing, but he coined a term that almost forces some such nonsense on you. It's as though he really really wants some explicit rationale to somehow be attached to the phenomenon itself – as opposed to the mind of a biologist inquiring into the mysteries of nature – but he can't see his way to sticking that rational into the mind of the animal. So he just lets it float there.
FFRs, Memes, and Handicaps
Whatever he was, thought he was, up to, Dennett did it, and now he keeps talking about these curious free-floating rationales: isn't nature wonderful? This reification strikes me as being somewhat like his memebots that flit from brain to brain, claiming neural real estate. These are the same memebots that infected the brains of apes and brought us into being.
It's as though however much he's committed to the computational view of the mind, in which mind is just a bunch of computational procedures running on neural wetware, he can't quite bring himself to believe it. And so he coins these terms to designate etherial nothings, memes and free-floating rationales.
But I can't help but wonder it there's also some power tripping going on. Ordinary scholars like you and me could never get away with saying things like this; they're too silly. But we're not Dan Dennett and he wants us to know that.
The operative mechanism is Zahavi's handicap princple. Some years ago I quoted Dawkins as explicating the principle in this way:
The premise of Zahavi's idea is that natural selection will favor skepticism among females (or among recipients of advertising messages generally). The only way for a male (or any advertiser) to authenticate his boast of strength (quality, or whatever is is) is to prove that it is true by shouldering a truly costly handicap — a handicap that only a genuinely strong (high quality, etc.) male could bear. It may be called the principle of costly authentication. And now to the point. Is it possible that some religious doctrines are favored not in spite of being ridiculous but precisely because they are ridiculous? Any wimp in religion could believe that bread symbolically represents the body of Christ, but it takes a real, red-blooded Catholic to believe something as daft as the transubstantiation. If you believe that you can believe anything, and (witness the story of Doubting Thomas) these people are trained to see that as a virtue.
Let me translate the next-to-last sentence: "Any materialist wimp could believe that brains really represent visual objects, but it takes a real, red-blooded evolutionist to believe something as daft as free-floating rationales." Or memebots and apes with infected brains.