Wednesday, February 12, 2014

The Secret Lives of Bats and Martians

Although evolution as it is presently understood involves a very long process of natural selection (among other arbitrary processes) without an overarching goal or forward progression toward a pre-defined or predictable result, this is not always appreciated. Some tend to believe, or at least act as if they believe, that evolution has accomplished its goal and reached its pinnacle, the end result being a species we’ve self-classified as homo sapien. Perhaps that is to be expected given that we are the only species capable of writing  On The Origin Of Species  and similar books that aim to explain the evolution of ourselves to ourselves. This hubristic tendency to think that evolution has done its work and the mantle is now passed to our capable hands (with opposable thumbs!) to mold reality as we wish engenders another false narrative, namely that we can figure everything out.

Because we comprehend many things, there is a tendency to think that we can eventually comprehend all things.  This, however, is most likely not the case.  It is more probable that there are facts beyond the grasp of human beings, facts which can never be represented or comprehended by us, no matter how much we believe the opposite.

Forty years ago the philosopher Thomas Nagel wrote an essay titled “What Is It Like To Be A Bat?”. The thrust of the article concerns questions of consciousness and specifically the mind-body problem of consciousness, but at the periphery of the discussion Nagel touches briefly on another topic, which he describes as “the relation between facts on the one hand and conceptual schemes or systems of representation on the other.”  It is this line of thought, coupled with the notion of subjectivity, which prompted him to invoke a “belief in the existence of facts beyond the reach of human concepts.”

Nagel writes, “Indeed, it would be foolish to doubt this, given (human) finiteness. There are facts which could not ever be comprehended by human beings, even if the species lasted for ever – simply because our structure does not permit us to operate with concepts of the requisite type.”  Nagel uses the example of a bat and what it is like to experience reality as this strange, nocturnal mammal as a way of highlighting the difficulties in a reductionist theory of conscious subjective experience. This example is also useful when considering our inaccessibility of certain facts.

Nagel chooses bats because they are mammals like us, a higher order vertebrate that doubtless has experience. Bats, although sharing our mammalian heritage, are nevertheless a species that Nagel describes as a “fundamentally alien form of life” since they “present a range of activity and a sensory apparatus so different from ours that the problem  is exceptionally vivid.”  Most bats perceive the external world by using echolocation, a form of sonar. Bats emit high-frequency sounds that reflect off objects within range.  Their brains then correlate these outgoing and incoming impulses to gather information that enable them to determine size, distance, movement and other factors which effectively correspond with our sense of vision. 

Even though we can understand and describe the principle of echolocation and recognize that it is a form of “bat vision”, our ability to conceive what such an experience would be like is “restricted to the resources of our own minds, and those resources are inadequate to the task.”  It is, according to Nagel, “not similar in its operation to any sense that we possess, and there is no reason to suppose that it is subjectively like anything we can experience or imagine.”  It will not help my case to think of myself hanging upside-down from a cave by my feet, or growing webbed wings and eating insects in the night sky by locating them with shrill sounds.  These images tell me only what it is like for me to behave like a bat. What we want to know is what it is like for a bat to be a bat.    

The same difficulty arises when we consider what it would be like for an alien species (a race of intelligent Martians, let’s say) to form a conception of what it is like to be us.  As Nagel suggests, “the structure of their own minds might make it impossible for them to succeed, but we know they would be wrong to conclude that there is not anything precise that it is like to be us: that only certain general types of mental state could be ascribed to us (perhaps perception and appetite would be concepts common to us both; perhaps not). We know they would be wrong to draw such a skeptical conclusion because we know what it is like to be us.”  Similarly, it might prove as improbable for us to conceptualize or comprehend the subjective experiences of alien beings vastly more intelligent than ourselves, since it could be the case that dissimilar structures of our respective mental processes would create an insurmountable barrier.

Nagel argues that “the fact that we cannot expect ever to accommodate in our language a detailed description of Martian or bat phenomenology should not lead us to dismiss as meaningless the claim that bats and Martians have experiences fully comparable in richness of detail to our own.”  The case that the subjective experiences of bats and Martians are facts from which humans are excluded from understanding does not invalidate the proposition that they nevertheless constitute a set of facts.  An extension of this rationale is the idea that since it is impossible for humans to represent or comprehend facts that our limited structure (and the limits of our technological inventions) prevent, the possibility exists that facts which are clearly evident to other creatures remain unknown to us.  “After all, the nature of beings with access to humanly inaccessible facts is presumably itself a humanly inaccessible fact”, Nagel suggests.  Only those facts to which we have access are meaningful to us.  This limited set does not constitute the whole.  It is merely the set to which we can gain access.

In summary, Nagel offers this thought, “It would be fine if someone were to develop concepts and a theory that enabled us to think about those things; but such an understanding may be permanently denied to us by the limits of our nature. And to deny the reality or logical significance of what we can never describe or understand is the crudest form of cognitive dissonance.”