The supposedly hard problem of consciousness and the nonexistence of sense data: Is your dog a conscious being?

Of dogs and cows

Are dogs con­scious? My guess, you think so: that’s why they’re termed “sen­tient.” We as­sume that dogs see the world much as we do, de­spite be­ing re­cep­tive to differ­ent in­for­ma­tion; they ex­pe­rience the same con­scious data of sense as we ex­pe­rience. You, nev­er­the­less, might be pre­pared to con­cede the ul­ti­mate un­fath­oma­bil­ity of the ques­tion, but if not, con­sider a re­lated ques­tion: when did con­scious­ness first arise in the course of or­ganic evolu­tion?

The rea­son the ques­tions are ob­scure de­serves scrutiny. I think I know you’re con­scious be­cause you say you know what I’m say­ing when I men­tion “con­scious­ness” or “ex­pe­rience,” but the limits of my knowl­edge of con­scious­ness are tel­ling: I will never find some phys­i­cal struc­ture to ex­plain it. This isn’t due to lack of em­piri­cal re­search or of the­o­ret­i­cal in­ge­nu­ity. To ex­plain an ob­ser­va­tion, you must de­scribe it, and the lan­guage used for de­scribing con­scious ex­pe­rience is the same lan­guage used for de­scribing the ob­ject the ex­pe­rience refers to. The most I can do to de­scribe the ex­pe­rienced “brown­ness” is achieved by refer­ring to its cause. When I see a brown cow, I can only de­scribe the raw ex­pe­rience as “brown”: the color that or­di­nar­ily gives rise to the ex­pe­rience. Thus, I nec­es­sar­ily omit from the de­scrip­tion ex­actly what I want to ex­plain: the qual­i­ta­tive char­ac­ter of the “brown” ex­pe­rience.

Ap­par­ent self-evidence

If qual­i­ta­tive con­scious­ness ex­isted, it would be ut­terly in­ex­pli­ca­ble; yet, the ev­i­dence of di­rect ex­pe­rience seems self-ev­i­dently to sup­port its own ex­is­tence. This seem­ingly im­me­di­ate aware­ness of our raw men­tal states seems to be just what it is like to be our­selves. (Thomas Nagel.) Re­gard­less of the ap­par­ent in­du­bita­bil­ity of the in­tu­ition that we have raw ex­pe­ri­en­tial states, this in­tu­ition re­mains noth­ing more than be­lief, and be­liefs are sub­ject to illu­sions that mis­lead us sys­tem­at­i­cally.

One rea­son you might re­sist the con­clu­sion that qual­i­ta­tive ex­pe­rience is illu­sory is whole­sale dis­tor­tion of re­al­ity re­gard­ing ob­jects of seem­ingly im­me­di­ate aware­ness seems im­plau­si­ble just be­cause of our in­ti­mate con­nec­tion with our own ex­pe­rience, but sci­en­tific de­vel­op­ments can ren­der seem­ingly un­re­lated philo­soph­i­cal po­si­tions plau­si­ble. The work of neu­rol­o­gists, such as Oliver Sacks, should cau­tion against the prej­u­dice that some ex­pe­riences are so ba­sic they re­sist rad­i­cal dis­tor­tion and fabri­ca­tion. An ex­am­ple Sacks de­scribes is a brain-dam­aged pa­tient who mis­took his wife for a hat. Neu­ro­scien­tists con­clude that cog­ni­tive func­tions are as­sem­blies of mod­ules, mak­ing it less startling that be­liefs can be so rad­i­cally wrong.

There’s also a con­cep­tual rea­son for the re­luc­tance of philoso­phers and sci­en­tists to re­ject the in­tu­ition of raw sense ex­pe­rience: lack of clar­ity about how to char­ac­ter­ize the prewired be­lief re­spon­si­ble for the illu­sion. The in­tu­ition seems too com­plex and so­phis­ti­cated to ac­com­mo­date in­nate be­lief; philoso­phers try­ing to nail down the pre­cise con­tent of the be­lief that qualia ex­ist have had re­course to thought ex­per­i­ments re­mote from ac­tual ex­pe­rience, and no­body seems to have char­ac­ter­ized the essence of qualia. My sug­ges­tion: the illu­sion of qual­i­ta­tive aware­ness is the be­lief that we when we per­ceive or imag­ine ob­jects, we have in­de­pen­dently real ex­pe­riences char­ac­ter­i­z­able only by the terms used to de­scribe the ex­ter­nal ob­ject it­self. Qualia are in­her­ently in­ef­fable con­tents of per­cep­tion or imag­i­na­tion.

The illu­sion’s evolution

This defi­ni­tion also sug­gests an evolu­tion­ary ex­pla­na­tion for the illu­sion of qual­i­ta­tive ex­pe­rience. Thought doesn’t de­pend on the illu­sion of con­scious­ness, as one can eas­ily con­ceive of an in­tel­li­gent be­ing with­out illu­sory be­liefs about the na­ture of the think­ing pro­cess, but the illu­sion of con­scious­ness might have en­couraged the de­vel­op­ment of think­ing. Per­haps hu­man an­ces­tors evolved the in­nate be­lief that they have ex­pe­riences with prop­er­ties cor­re­spond­ing to those of their refer­ents be­cause this be­lief en­couraged our an­ces­tors to make men­tal mod­els of the world—en­couraged them to en­gage in the offline think­ing unique for our species. Ob­jec­tified con­scious ex­pe­rience could en­courage men­tal-model mak­ing by gen­er­al­iz­ing the prior in­sight that you can pre­dict one ex­ter­nal ob­ject by ma­nipu­lat­ing a similar ex­ter­nal ob­ject. Our an­ces­tors would then need only sub­sti­tute in­ter­nal ob­jects for ex­ter­nal ones.

By­pass­ing “sense data” in the the­ory of knowledge

Ac­cord­ing to one long­stand­ing the­ory in episte­mol­ogy, sense data are our only ba­sis for know­ing the ex­ter­nal world. This doc­trine, taken to its log­i­cal con­clu­sion, leads to skep­ti­cism about the ex­ter­nal world’s ex­is­tence: sense data, sup­pos­edly our win­dow to the world, be­came an in­su­per­a­ble bar­rier to cog­ni­tion, for if all our knowl­edge is noth­ing but con­struc­tion from sense data, our sense data are all we know. We can’t get out of our own minds.

The rea­son the sense data the­ory leads to skep­ti­cal con­clu­sions goes back to in­ef­fa­bil­ity. If we know the world by sense data, you can draw con­clu­sions about the world only through anal­ogy, that is, by form­ing a re­la­tion­ship be­tween two de­scrip­tions. Inef­fable sense data have noth­ing in com­mon with a world of things, ex­cept their names —such as “brown­ness.”

Two illusions

This ac­count of raw ex­pe­rience as an adap­tive illu­sion brings clar­ity to the ar­gu­ment that free will is illu­sory. The sense of free will, I con­cluded, is the mis­per­cep­tion that ex­pe­rienced de­cid­ing causes be­hav­ior. But “ex­pe­rience” doesn’t ex­ist. Com­pat­i­bil­ist free will is in­co­her­ent be­cause it as­sumes the causal effi­cacy of un­real raw ex­pe­rience.

[Cross-posted at http://​​ju­ridi­cal­co­her­​​2012/​​08/​​160-sup­pos­edly-hard-prob­lem-of.html]