Most of us have no doubt that our fellow humans are conscious.We are also pretty sure that many animals have consciousness. Some,like the great ape species, even seem to possess self-consciousness,like us. Others, like dogs and cats and pigs, may lack a sense of self,but they certainly appear to experience inner states of pain andpleasure. About smaller creatures, like mosquitoes, we are not so sure;certainly we have few compunctions about killing them. As for plants,they obviously do not have minds, except in fairy tales. Nor dononliving things like tables and rocks.
All that is common sense. But common sense has not always proved tobe such a good guide in understanding the world. And the part of ourworld that is most recalcitrant to our understanding at the moment isconsciousness itself. How could the electrochemical processes in thelump of gray matter that is our brain give rise to — or, even moremysteriously, be — the dazzling technicolor play ofconsciousness, with its transports of joy, its stabs of anguish and itsstretches of mild contentment alternating with boredom? This has beencalled “the most important problem in the biological sciences” and even“the last frontier of science.” It engrosses the intellectual energiesof a worldwide community of brain scientists, psychologists,philosophers, physicists, computer scientists and even, from time totime, the Dalai Lama.
Sovexing has the problem of consciousness proved that some of thesethinkers have been driven to a hypothesis that sounds desperate, if notdownright crazy. Perhaps, they say, mind is not limited to the brainsof some animals. Perhaps it is ubiquitous, present in every bit ofmatter, all the way up to galaxies, all the way down to electrons andneutrinos, not excluding medium-size things like a glass of water or apotted plant. Moreover, it did not suddenly arise when some physicalparticles on a certain planet chanced to come into the rightconfiguration; rather, there has been consciousness in the cosmos fromthe very beginning of time.
The doctrine that the stuff of theworld is fundamentally mind-stuff goes by the name of panpsychism. Afew decades ago, the American philosopher Thomas Nagel showed that itis an inescapable consequence of some quite reasonable premises. First,our brains consist of material particles. Second, these particles, incertain arrangements, produce subjective thoughts and feelings. Third,physical properties alone cannot account for subjectivity. (How couldthe ineffable experience of tasting a strawberry ever arise from theequations of physics?) Now, Nagel reasoned, the properties of a complexsystem like the brain don’t just pop into existence from nowhere; theymust derive from the properties of that system’s ultimate constituents.Those ultimate constituents must therefore have subjective featuresthemselves — features that, in the right combinations, add up to ourinner thoughts and feelings. But the electrons, protons and neutronsmaking up our brains are no different from those making up the rest ofthe world. So the entire universe must consist of little bits ofconsciousness.
Nagel himself stopped short of embracingpanpsychism, but today it is enjoying something of a vogue. TheAustralian philosopher David Chalmers and the Oxford physicist RogerPenrose have spoken on its behalf. In the recent book “Consciousnessand Its Place in Nature,” the British philosopher Galen Strawsondefends panpsychism against numerous critics. How, the skeptics wonder,could bits of mind-dust, with their presumably simple mental states,combine to form the kinds of complicated experiences we humans have?After all, when you put a bunch of people in the same room, theirindividual minds do not form a single collective mind. (Or do they?)Then there is the inconvenient fact that you can’t scientifically testthe claim that, say, the moon is having mental experiences. (But thesame applies to people — how could you prove that your fellow officeworkers aren’t unconscious robots, like Commander Data on “Star Trek”?)Finally, there is the sheer loopiness of the idea that something like aphoton could have proto-emotions, proto-beliefs and proto-desires. Whatcould the content of a photon’s desire possibly be? “Perhaps it wishesit were a quark,” one anti-panpsychist cracked.
Panpsychism maybe easier to parody than to refute. But even if it proves a cul-de-sacin the quest to understand consciousness, it might still help rouse usfrom a certain parochiality in our cosmic outlook. We are biologicalbeings. We exist because of self-replicating chemicals. We detect andact on information from our environment so that the self-replicationwill continue. As a byproduct, we have developed brains that, we fondlybelieve, are the most intricate things in the universe. We look downour noses at brute matter.
Take that rock over there. It doesn’tseem to be doing much of anything, at least to our gross perception.But at the microlevel it consists of an unimaginable number of atomsconnected by springy chemical bonds, all jiggling around at a rate thateven our fastest supercomputer might envy. And they are not jiggling atrandom. The rock’s innards “see” the entire universe by means of thegravitational and electromagnetic signals it is continuously receiving.Such a system can be viewed as an all-purpose information processor,one whose inner dynamics mirror any sequence of mental states that ourbrains might run through. And where there is information, sayspanpsychism, there is consciousness. In David Chalmers’s slogan,“Experience is information from the inside; physics is information fromthe outside.”
But the rock doesn’t exert itself as a result ofall this “thinking.” Why should it? Its existence, unlike ours, doesn’tdepend on the struggle to survive and self-replicate. It is indifferentto the prospect of being pulverized. If you are poetically inclined,you might think of the rock as a purely contemplative being. And youmight draw the moral that the universe is, and always has been,saturated with mind, even though we snobbish Darwinian-replicatinglatecomers are too blinkered to notice.
Jim Holt, a contributing writer, is working on a book about the puzzle of existence.作者: 天灵灵地灵灵 时间: 2007-11-20 17:00
