human-looking creature not achieve the same things we do, in a 

 totally automatic fashion? This is the so-called zombie argument, 

 first raised by Robert Kirk (1974). The answer lies in that innocent- 

 looking need to distinguish between external sensory input and sen- 

 sory input the creature itself has provoked, when the prospect of 

 novel behavior is in the offing. This is vital, because the creature 

 can control only the latter variety of input. In default of its being 

 able to make the distinction, the creature will not be aware that it 

 is the agent of its own actions. 



But why should having such a discriminatory mechanism produce 

 consciousness? Why should the experience of raw sensations be the 

 crucial factor? Ned Block (2002) tells a story — apparently ancient 

 among philosophers — about a biographer who is researching for a 

 book about Mark Twain, and he gradually becomes aware that there 

 is a mysterious second person, named Samuel Clemens, who seems 

 to have led a remarkably similar life, almost as if he were acting as 

 Twain's shadow. Everywhere that Twain went, Clemens went, and 

 everything that Twain did, Clemens did too. Finally, it dawns on 

 the writer that Twain was Clemens, and that Mark Twain was merely 

 a pseudonym. I believe that the same is true of what we have just 

 been discussing. Those raw sensations, and the awareness they me- 

 diate — vitally permitting the animal to distinguish between the dif- 

 ferent types of sensory input — imply are consciousness. 



And this reveals the raison d'etre of the phenomenon, because 

 that ability to make reliable distinctions permits augmentation of the 

 unconscious movement repertoire that the animal was born with. 

 Consciousness enables an animal to acquire new context-specific 

 reflexes — new schemata indeed — during its own lifetime. The reader 

 is using such acquired reflexes as these words are read. They were 

 certainly not there at birth. They had to be learned, and such learning 

 involved the discrimination that is the hallmark of consciousness. 



We ought to look at that learning mechanism in more detail, and 

 let's return to those questions asked about the ground by our moving 

 feet. They can be made unconsciously because we are expert at 

 walking. But When we were learning to walk, each tentative step 

 had to be the focus of attention. Similarly, when learning to speak, 

 we carefully intoned each syllable, linking those sound fragments 



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