The curious nitpicker might be saying "Yeah, but without genes how do these guys evolve? How to they adapt to novel environments? How, as a species, do they cope with the unexpected?" And if Robert Cunningham were here today, he might say, "I'd swear half the immune system is actively targetting the other half. It's not just the immune system, either. Parts of the nervous system seem to be trying to, well, hack each other. I think they evolve intraorganismally, as insane as that sounds. The whole organism's at war with itself on the tissue level, it's got some kind of cellular Red Queen thing happening. Like setting up a colony of interacting tumors, and counting on fierce competition to keep any one of them from getting out of hand. Seems to serve the same role as sex and mutation does for us." And if you rolled your eyes at all that doubletalk, he might just blow smoke in your face and refer to one immunologist's interpretation of exactly those concepts, as exemplified in (of all things) The Matrix Revolutions [93]. He might also point out that that the synaptic connections of your own brain are shaped by a similar kind of intraorganismal natural selection [94], one catalysed by bits of parasitic DNA called retrotransposons.

Cunningham actually did say something like that in an earlier draft of this book, but the damn thing was getting so weighed down with theorising that I just cut it. After all, Rorschach is the proximate architect of these things, so it could handle all that stuff even if individual scramblers couldn't. And one of Blindsight's take-home messages is that life is a matter of degree—the distinction between living and non-living systems has always been an iffy one [95, 96, 97], never more so than in the bowels of that pain-in-the-ass artefact out in the Oort.

This is the heart of the whole damn exercise. Let's get the biggies out of the way first. Metzinger's Being No One [20] is the toughest book I've ever read (and there are still significant chunks of it I haven't), but it also contains some of the most mindblowing ideas I've encountered in fact or fiction. Most authors are shameless bait-and-switchers when it comes to the nature of consciousness. Pinker calls his book How the Mind Works [98], then admits on page one that "We don't understand how the mind works". Koch (the guy who coined the term "zombie agents") writes The Quest for Consciousness: A Neurobiological Approach [99], in which he sheepishly sidesteps the whole issue of why neural activity should result in any kind of subjective awareness whatsoever.

Towering above such pussies, Metzinger takes the bull by the balls. His «World-zero» hypothesis not only explains the subjective sense of self, but also why such an illusory first-person narrator would be an emergent property of certain cognitive systems in the first place. I have no idea whether he's right— the man's way beyond me— but at least he addressed the real question that keeps us staring at the ceiling at three a.m., long after the last roach is spent. Many of the syndromes and maladies dropped into Blindsight I first encountered in Metzinger's book. Any uncited claims or statements in this subsection probably hail from that source.

If they don't, then maybe they hail from Wegner's The Illusion of Conscious Will [21] instead. Less ambitious, far more accessible, Wegner's book doesn't so much deal with the nature of consciousness as it does with the nature of free will, which Wegner thumbnails as "our mind's way of estimating what it thinks it did.". Wegner presents his own list of syndromes and maladies, all of which reinforce the mind-boggling sense of what fragile and subvertible machines we are. And of course, Oliver Saks [22] was sending us memos from the edge of consciousness long before consciousness even had a bandwagon to jump on.

It might be easier to list the people who haven't taken a stab at «explaining» consciousness. Theories run the gamut from diffuse electrical fields to quantum puppet-shows; consciousness has been «located» in the frontoinsular cortex and the hypothalamus and a hundred dynamic cores in between [100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110]. (At least one theory [111] suggests that while great apes and adult Humans are sentient, young Human children are not. I admit to a certain fondness for this conclusion; if childen aren't nonsentient, they're certainly psychopathic).

But beneath the unthreatening, superficial question of what consciousness is floats the more functional question of what it's good for. Blindsight plays with that issue at length, and I won't reiterate points already made. Suffice to say that, at least under routine conditions, consciousness does little beyond taking memos from the vastly richer subconcious environment, rubber-stamping them, and taking the credit for itself. In fact, the nonconscious mind usually works so well on its own that it actually employs a gatekeeper in the anterious cingulate cortex to do nothing but prevent the conscious self from interfering in daily operations [112, 113, 114]. (If the rest of your brain were conscious, it would probably regard you as the pointy-haired boss from Dilbert.)

Sentience isn't even necessary to develop a "theory of mind". That might seem completely counterintuitive: how could you learn to recognise that other individuals are autonomous agents, with their own interests and agendas, if you weren't even aware of your own? But there's no contradiction, and no call for consciousness. It is entirely possible to track the intentions of others without being the slightest bit self-reflective[107]. Norretranders declared outright that "Consciousness is a fraud" [115].

Art might be a bit of an exception. Aesthetics seem to require some level of self-awareness—in fact, the evolution of aethestics might even be what got the whole sentience ball rolling in the first place. When music is so beautiful if makes you shiver, that's the reward circuitry in your limbic system kicking in: the same circuitry that rewards you for fucking an attractive partner or gorging on sucrose [116]. It's a hack, in other words; your brain has learned how to get the reward without actually earning it through increased fitness[98]. It feels good, and it fulfills us, and it makes life worth living. But it also turns us inward and distracts us. Those rats back in the sixties, the ones that learned to stimulate their own pleasure centers by pressing a lever: remember them? They pressed those levers with such addictive zeal that they forgot to eat. They starved to death. I've no doubt they died happy, but they died. Without issue. Their fitness went to Zero.