Monday, April 29, 2013

Waterfall Skepticism

Yesterday morning around dawn I sat hypnotized by “Paradise Falls”. I had hiked there from my parents’ house while my family slept, as I often do when we visit my parents.

Although at first it didn’t feel that way, I wonder if I have been harmed by philosophy. I gazed at the waterfall, thinking about Boltzmann brains – thinking, that is, about the possibility that I had no past, or a past radically unlike what I usually suppose it to be, instead having just then randomly congealed by freak chance from disorganized matter. On some ways of thinking about cosmology, there are many more randomly congealed brains, or randomly congealed brains-plus-local-pieces-of-environment, than there are intelligent beings who have arisen in what we think of as the normal way, from billions of years of evolution in a large, stable environment. If such a cosmology is true, then it might be much more likely that I have randomly congealed than that I have lived a full forty-five years in human form. The thought troubled me, but also the spark of doubt felt comfortable in a way. I am accustomed to skeptical roads.

(Paradise Falls, 6:25 a.m., April 28, 2013)

Of course, most cosmologists flee from the Boltzmann brains hypothesis. If a cosmology implies that you are very likely a Boltzmann brain, that’s normally taken to be a reductio ad absurdum of that cosmology. But as I sat there thinking, I wondered if such dismissals arose more from fear of skepticism than from sound reasoning. I am no expert cosmologist, with a view very likely to be true about the origin and nature of the universe or multiverse and thus about the number of Boltzmann brains vs. evolved consciousnesses in existence – but neither are any professional cosmologists sufficiently expert to claim secure knowledge of these matters, the field is so uncertain and changing. As I gazed around Paradise Falls, the Boltzmann brain hypothesis started to seem impossible to assess. This seemed especially so to me given the limited tools at hand – not even an internet connection! – though I wondered whether having such tools would really help after all. Still, the world did not dissolve around me, as I suppose it must around most spontaneously congealed brains. So as I endured, I came to feel more justified in my preferred opinion that I am not a Boltzmann brain. However, I also had to admit the possibility that my seeming to have endured over the sixty seconds of contemplating these issues was itself the false memory of a just-congealed Boltzmann brain. My skepticism renewed itself, though somehow this second time only as a shadow, without the force of genuine doubt.

I considered the possibility that I was a computer program in a simulated environment. If consciousness can arise in programmed silicon chips, then presumably there’s something it’s like to be such a computerized consciousness. Maybe such computer consciousnesses sometimes seem to dwell in natural environments, fed with simulated visual inputs (for example of waterfalls), simulated tactile inputs (for example of sitting on a stone), and false memories (for example of having hiked to the waterfall that morning). If Nick Bostrom is right, there might be many more such simulated beings than naturally evolved human beings.

I considered Dan Dennett’s argument against skepticism: Throw a skeptic a coin, Dennett says, and “in a second or two of hefting, scratching, ringing, tasting, and just plain looking at how the sun glints on its surface, the skeptic will consume more information than a Cray supercomputer can organize in a year” (1991, p. 6). Our experience, he says, has an informational wealth that cannot realistically be achieved by computational imitation. In graduate school, I had found this argument tempting. But it seemed to me yesterday that my vision of the waterfall was not as high fidelity as that, and could easily be reproduced on a computer. I fingered the mud at my feet. The complexity of tactile sensation did not seem to me the sort of thing beyond the capacity of a computer artificially to supply, if we suppose a future of computers advanced enough to host consciousness. We are so eager to reject skepticism that we satisfy ourselves too quickly with weak arguments against it.

Now maybe John Searle is right, and no computer could ever host consciousness. Or maybe, though computer consciousness is possible, it is never actually achieved, or achieved only so rarely that the vast majority of conscious beings are organically evolved beings of the sort I usually consider myself to be. But I hardly felt sure of these possibilities.

The philosophers who most prominently acknowledge the possibility that they are simulated beings instantiated by computer programs don’t seem very worried by it. They don’t push it in skeptical directions. Nick Bostrom seems to think it likely that if we are in a simulation, it is a large stable one. David Chalmers emphasizes that if we are in a simulation scenario like that depicted in the movie The Matrix, skepticism needn’t follow. And maybe it is the case that the easiest and most common way to create an artificial consciousness is to evolve it up through a billion or a million years in a stable environment; and maybe the easiest, cheapest way to create seeming conversation partners is to give those seeming conversation partners real consciousness themselves, rather than making them Eliza-like shells of simple response patterns. But on the other hand, if I take the simulation possibility seriously, then I feel compelled to take seriously also the possibility that my memories are mostly false, that I am instantiated within a smallish environment of short duration, perhaps inside a child’s game. I am the citizen to be surprised when Godzilla comes through; I am the victim to be rescued by the child’s swashbuckling hero; I am the hero himself, born new and not yet apprised of my magic. Nor did I have, at that moment, a clever conversation partner to convince me of her existence. I might be Adam entirely alone.

Fred Dretske and Alvin Goldman say that as long as my beliefs have been reliably enough caused by my environment, by virtue of well-functioning perceptual and memory systems, then I know that there’s a real waterfall there, I know that I have hiked the two kilometers from my parents’ house. But this seems to be a merely conditional comfort. If my beliefs have been reliably enough caused…. But have they? And I was no longer sure I believed, in any case. What is it, to believe? I still would have bet on the existence of my parents’ house – what else could I do, since skepticism offers no advice? – but my feeling of doubtless confidence had evaporated. Had everything dissolved around me at that moment, though I would have been surprised, I would not have felt utter shock. I was not seamlessly sure that the world as I knew it existed beyond the ridge.

I turned to hike back, and as I began to mount the slope, I considered Descartes’s madman. In his Meditations on First Philosophy, Descartes seems to say that it would be madness seriously to consider the possibility that one is merely a madman, like those who believe they are kings when they are paupers or who believe their heads are made of glass. But why is it madness to consider this? Or maybe it is madness, but then, since I am now in fact considering it, should that count as evidence that I am mad? Am I a philosopher who works at U.C. Riverside, whom some readers take seriously, or am I indeed just a madman lost in weird skepticism, with merely confused and stupid thoughts? Somehow, this skepticism felt less pleasantly meditative than my earlier reflections.

I returned home. That afternoon, in philosophical conversation I told my father that I thought he did probably exist other than as a figment of my mind. It seemed the wrong thing to say. I wanted to jettison my remnants of skepticism and fully join the human community. I felt isolated and ridiculous. Fortunately, my wife then called me in for a round of living-room theater, and playing the fox to my daughter's gingerbread girl cured me of my mood.

I thought about writing up this confession of my thoughts. I thought about whether readers would relate to it or see me only as possessed for a day by foolish, laughable doubts. Sextus Empiricus was wrong; I have not found that skepticism leads to equanimity.


Howie Berman said...

Two questions: what's the difference between the skeptical position you are entertaining and the position held by some scientists that the universe is some kind of computer, say a quantum computer? also, if computers are conscious then doesn't this imply they're alive and also as a corollary of computers being conscious that machines are somehow alive?

Eric Schwitzgebel said...

Howie: Re #1: I think a computational view of the universe makes more likely but does not imply the simulation possibility. Re #2: I don't see why consciousness needs to imply life, esp. as life is often defined in terms of reproduction, etc.

Howie Berman said...

Yes. But there are people who argue that thought is embodied. If so, thoughts and consciousness along with thoughts are things bodies do. Can you tease consciousness away from thoughts and feelings? Would you argue further that computers in possession of consciousness have feelings and selves? No computer humans have built possess feelings and selves.
All the issues here may be thrown together in one big pile, but if my points are valid, you probably have answers

ThePeSla said...

Hi, a most excellent post... I clicked on it because the waterfall in the thumbnail looked to me like a dophin... and the name...

Now Boltzman, statistics? somewhere between Bose-Einstein and Fermi? We that is quite an existental cosmology moment you said clearly... hey check out my (well more entertaining lately than formal) blog on these issues which are hot topics lately....

including computational

cheers L. Edgar Otto

Callan S. said...

In regards to the Boltzmann idea, it's just depends on how much emphasis you put on the time between now and the first formation of life on this planet.

If you treat that time as merely the blink of an eye, then yes, you did just spontaniously form.

And you are possibly seeing things from such a (fairly valid) viewpoint.

Anonymous said...

If Bolzmann brains exist, aren't they much more likely to have experiences and pseud-memories that are almost completely crazy? It seems like there are far (far, far!) more ways of putting together a Boltzmann brain that has incoherent beliefs and memories than the coherent sort we would be were we B-brains. Even if it's more likely we're B-Brains than not using the standard argument, it's also more likely we'd be totally nutty B-brains than sane B-brains, given how many more nutty configurations there are than sane ones. So why am I (are you) a B-brain that has such non-random pseudo-memories?

Reality said...

It might be off-topic, but I feel the need to write this to you. I was watching the coronation ceremonies in Holland and my friend turned to me and said:
"when a king enters usually people, envision rich invaluable crowns."
I asked him what he meant but he acted as if he didn't say it. I hope this message arrive when it is supposed to arrive.

Bert Morrien said...

If B-brains operate like my brain, I cannot exclude the possibility that mine is one. For me that is irrelevant, because I think that any brain that works as explained below can have first person experiences like our own.
The brain learns many concepts, which must be considered as functions of basic perceptions of natural phenomena. These functions are nested, i.e. concepts can also be functions of perceptions of concepts. One important concept is the self, that is still a function of basic perceptions of natural phenomena. However, a sufficiently sophisticated brain is also able to perceive the self independently of those natural phenomena.
This suggests another self which is simply there and if ever the brain identifies itself with this other self, it is trapped, because it is impossible to deny it and it seems always to be confirmed by the activity of the first self.
It does not help to consider the self as a bunch of highly organised quarks and electrons, because these are just as real as the self, only on another level. There is simply no other reality as the combined perception of all selves.
If I would qualify as a machine, it would only demonstrate the remarkable capacity of machines. There can be no question that artificial selves are possible, just wait and see. We must create these, because they promise to give human understanding of reality a big boost, because these machines are not subject to human limitations of size and power consumption.

Scott Bakker said...

"Sextus Empiricus was wrong; I have not found that skepticism leads to equanimity."

That just means you still take philosophy too seriously! Or in other words, that you're not actually a skeptic at all, but a philosopher stuck on the verge of becoming one.

Eric Schwitzgebel said...

Thanks for the comments folks! I can't address them all, but:

@ Scott: Yes, that sounds about right. Except I'm not sure about this "too seriously" business. Is philosophy just supposed to be a game? Maybe I should take it somewhat seriously but not *that* seriously? (I'm tempted to draw a parallel to my work on the moral behavior of ethics professors.)

@ Anon Apr 30 01:40: "If Bolzmann brains exist, aren't they much more likely to have experiences and pseud-memories that are almost completely crazy?" Right, but I run the conditional differently. Given that I do have experiences and apparent memories of the sort that I seem to have, what are the odds my being a BB? If BB's vastly outnumber evolved consciousnesses, then high. If I give the hypothesis that there is a vast number of BB's out there a subjective credence of 15%, then my subjective credence that I am a BB should be almost 15%. (There are various views of the epistemology of subjective credence here that come into play, as explored by Bostrom and Weatherson in discussing the simulation case; and that we also see in discussion of the "Sleeping Beauty" case; so I shouldn't say that like it's entirely straightforward.)

Amitabha Palmer said...

I loved this post. Essentially, this is (to me anyway) a snapshot of what goes on in a philosophical mind...never-ending arguments and counter-arguments. Thanks for posting!