Skyhooks and cranes

Originally published 14 October 2007

Some one-word titles in the psy­chol­o­gy sec­tion of the library: Soli­tude, Com­pas­sion, Self-hate, Laugh­ter, Jeal­ousy, Regret, Shame, Prej­u­dice, Vio­lence, Anger, Embar­rass­ment. And that’s just for starters. It seems every psy­chol­o­gist has carved out his or her own lit­tle niche of the human dra­ma for close scruti­ny. Of course, all of these titles are sub­sets of a book that could be called sim­ply Con­scious­ness. And, yes, here is a title that grabs our atten­tion: Con­scious­ness Explained, by the emi­nent philoso­pher of cog­ni­tion Daniel Den­nett.

For my mon­ey, I’ll take a few pages of Den­nett over any of titles men­tioned above. He’s one smart fel­low. But when I had fin­ished read­ing Con­scious­ness Explained I was still hun­gry. The title promis­es way more than it can pos­si­bly deliv­er, giv­en the present state of neu­ro­log­i­cal stud­ies. What’s on offer in Den­net­t’s book is not an expla­na­tion of con­scious­ness but a plau­si­ble idea of what the expla­na­tion might even­tu­al­ly turn out to be.

Den­nett has a pen­chant for auda­cious titles. The sub­ti­tle of Dar­win’s Dan­ger­ous Idea: Evo­lu­tion and the Mean­ings of Life again bites off more than the book can chew. The mean­ings of life! Wow! Sure­ly dear old Dar­win him­self would not aspire to that lev­el of hubris. Mon­ty Python can get away with The Mean­ing of Life as a title, but not Mr. Dennett.

But let’s be fair. It is not the mean­ings of my life or your life that Den­nett sets out to define, but the mean­ings of life itself, the whole grand sweep of it, ascend­ing from the pri­mor­dial slime to — well, to you and me, the pre­sumed pin­na­cles of it all. The big ques­tion is how we got here. Was our exis­tence fore­or­dained, drawn up as by a sky­hook from the drea­ry world of mat­ter into the realm of angels? Or are we the unfore­seen accu­mu­la­tion of blind, chance muta­tions select­ed by inter­ac­tion with the envi­ron­ment, mat­ter lift­ing itself into ever greater domains of com­plex­i­ty, even­tu­al­ly into con­scious­ness, as if by those cranes used by builders of sky­scrap­ers that ratch­et upward as the build­ings rise?

There is no more deeply entrenched idea in human cul­ture than that we are more than the sum of our parts, our bod­ies more than bio­log­i­cal automa­tons, our minds more than fleshy com­put­ers. Accord­ing to the most wide­ly-held view, we have been plucked like ripe fruit from the Tree of Life by a pow­er greater than our­selves (the sky­hook) and allowed to par­tic­i­pate in a grander, lofti­er kind of exis­tence. For many peo­ple the sky­hook is a super­nat­ur­al God. For oth­ers, includ­ing some of the bright­est sci­en­tists work­ing today, some oth­er kind of sky­hook — cos­mic mind, emer­gent evo­lu­tion, or what­ev­er — does the job.

Against all these sky­hook philoso­phies, Den­nett vig­or­ous­ly defends the Dar­win­ian crane. It was Dar­win’s great insight, he says, that all of the crea­tures on the plan­et, and all of their prop­er­ties — eggs, hair, back­bones, gen­i­talia, con­scious­ness — could be the prod­ucts of an auto­mat­ic and grad­ual lifter, act­ing over eons of time, a process as patient as it was mind­less. Mean­ing does­n’t come from on high, says Den­nett; it per­co­lates up from below, from ini­tial­ly mind­less and point­less process­es that grad­u­al­ly acquire mean­ing and intel­li­gence as they devel­op — physics to chem­istry to biol­o­gy to mind.

This is philo­soph­i­cal Dar­win­ism at its strongest. Accord­ing to Den­nett, not only do organ­isms evolve, but so does mean­ing. It required bil­lions of years of life ris­ing to new lev­els of func­tion­al­i­ty and pur­po­sive­ness before full-fledged inten­tion­al­i­ty could appear. And just as it is hard to draw lines in the record of life and say, “This is a bird, this is not a bird,” so is mean­ing a mat­ter of incre­men­tal accumulation.

The strength of Den­net­t’s the­sis is the force of mind he brings to the argu­ment. He knows his clas­si­cal phi­los­o­phy. He also knows his sci­ence. He is broad­ly knowl­edge­able about evo­lu­tion­ary biol­o­gy, com­put­er sci­ence, and the sci­ence of Arti­fi­cial Intel­li­gence, three dis­ci­plines of immense rel­e­vance to his top­ic. He takes on his sky­hook col­leagues with gus­to and humor; indeed, it would be hard to find a bet­ter exam­ple of the respect­ful rough-and-tum­ble of good sci­en­tif­ic debate than you meet in a Den­nett book. Every argu­ment is up for grabs. “This book…is for those who agree that the only mean­ing of life worth car­ing about is one that can with­stand our best efforts to exam­ine it,” Den­nett writes on an ear­ly page, echo­ing Socrates (“The unex­am­ined life is not worth liv­ing.”). Any­one who does not want their dear­est pre­sump­tions chal­lenged “are advised to close the book now and tip­toe away.”

Den­net­t’s strong Dar­win­ism is com­pelling­ly expressed. How­ev­er, this hum­ble read­er is not con­vinced that we yet know enough about life or mind to com­mit our­selves sole­ly to cranes or sky­hooks. No one who is remote­ly knowl­edge­able about sci­ence doubts that life and con­scious­ness evolved over bil­lions of years; what is still at issue is how com­plex­i­ty and con­scious­ness arise. Is nat­ur­al selec­tion enough to dri­ve evo­lu­tion toward ever more sophis­ti­cat­ed sys­tems? Or is there a nat­ur­al ten­den­cy toward com­plex­i­ty and con­scious­ness built into cre­ation from the very begin­ning, a law­ful nat­ur­al sky­hook of sorts that might be acces­si­ble to sci­en­tif­ic descrip­tion? In my mind, the issue is undecided.

What is not in doubt at the moment is the pow­er of the Dar­win­ian idea. So far, the crane has been far and away the most fruit­ful way for doing science.