Lecture: on the subjective experience of Nagel's bat

[fit] what is it like to be a bat?

by Thomas Nagel, 1974 dgoodwin 16 march 2016

Nagel's bats are more like this one:

The microbats constitute the now outdated suborder Microchiroptera within the order Chiroptera.

• Microbats use echolocation, whereas megabats do not typically.
• Microbats lack the claw at the second finger of the forelimb. This finger appears thinner and almost bonded by tissue with the third finger for extra support during flight.
• Megabats always lack a tail
• The ears of microbats possess a tragus and are larger, megabat ears are comparatively small and lack a tragus.
• Megabat eyes are quite large

tragus

The tragus is a small pointed eminence of the external ear, situated in front of the concha, and projecting backward over the meatus. It also is the name of hair growing at the entrance of the ear.[1] Its name comes from the Greek: tragos, goat, and is descriptive of its general covering on its under surface with a tuft of hair, resembling a goat's beard.

How do mental states, events and processes (beliefs, actions and thinking) relate to the physical states, events and processes when the human body is a physical entity and the mind is non-physical?

consciousness makes the mind-body problem really intractable.

The recent wave of reductionist euphoria has produced several analyses of mental phenomena and mental concepts designed to explain the possibility of some variety of materialism, psychophysical identification, or reduction.

Reductionists are those who take one theory or phenomenon to be reducible to some other theory or phenomenon.

the water-H2O problem

You may argue that compounds like water are dynamic structures with natures that cannot be given in static accounts of their composing elements. Does "H2O" fully characterize water, ice and steam?

Consciousness makes the mind-body problem interesting

it is consciousness that delivers the what it's like to be a something.

We propose that living beings at many levels of sophistication have conscious experience. Including small nocturnal mammals that hang from caves. We propose that

bats have consciousness and that that there exists something that it is like to be a bat.

Call this the subjective character of experience. It is not captured by reductive analysis of mental life. There is no computer program that will expound on what it is like to be an algorithm.

Bats, although more closely related to us than those other species, nevertheless present a range of activity and a sensory apparatus so different from ours that the problem I want to pose is exceptionally vivid...

Anyone who has spent some time in an enclosed space with an excited bat knows what it is to encounter a fundamentally alien form of life.

Their brains are designed to correlate the outgoing impulses with the subsequent echoes, and the information thus acquired

enables bats to make precise discriminations of distance, size, shape, motion, and texture comparable to those we make by vision.

But bat sonar, though clearly a form of perception, is not similar in its operation to any sense that we possess

there is no reason to suppose that it is subjectively like anything we can experience or imagine.

This appears to create difficulties for the notion of what it is like to be a bat.

We must consider whether any method will permit us to extrapolate to the inner life of the bat from our own case, and if not, what alternative methods there may be for understanding the notion.

It will not help to try to imagine that one has webbing on one's arms, which enables one to fly around at dusk and dawn catching insects in one's mouth; that one has very poor vision, and perceives the surrounding world by a system of reflected high-frequency sound signals; and that one spends the day hanging upside down by one's feet in an attic.

But that is not the question. I want to know what it is like for a bat to be a bat.

The best evidence would come from the experiences of bats, if we only knew what they were like.

The subjective character of the experience of a person deaf and blind from birth is not accessible to me...

This does not prevent us each from believing that the other's experience has such a subjective character.

I am not adverting here to the alleged privacy of experience to its possessor. The point of view in question is not one accessible only to a single individual. Rather,

This experience is a type.

The more different from oneself the other experiencer is, the less success one can expect with this enterprise.

This is not by itself an argument against reduction.

A Martian without visual perception could understand the rainbow, or lightning, or clouds as physical phenomena but...

it would not understand the human concepts of rainbow, lightning, or cloud, or the place these things occupy in our phenomenal world.

a general difficulty about psychophysical reduction. ...

In a sense, the seeds of this objection to the reducibility of experience are already detectable in successful cases of reduction

Members of radically different species may both understand the same physical events in objective terms,

this does not require that they understand the phenomenal forms in which those events appear to the senses of members of the other species.

our own mental activity is the only unquestionable fact of our experience

individuals know what it is like to be them (Subjectivism). Objectivity, requires an unbiased, non-subjective state of perception.

For Nagel, the objective perspective is not practicable, because humans are limited to subjective experience.

however one might try to develop concepts that could be used to explain to a person blind from birth what it was like to see.

it should be possible to devise a method to express in objective terms much more than we can at present, and with more precision.

how would you do it?

strategies

1. expand human vision to include other senses (reciprocity of subject/object)
2. qualify the experience of navigating by echolocation
3. reproduce the pressures that resulted in adaptations to the bat's morphology.

James J Gibson

The supposedly separate realms of subjective and objective are actually only poles of attention. The dualism of observer and environment is unnecessary.

The information for the perception of 'here' is of the same kind as the information for the perception of 'there'

a continuous layout of surfaces extends from one to the other.

[fit] consider the way Gibson uses the word

information ...

according to Gibson, examination of the relations between surfaces is enough to determine the structure of both organism and environment.

the surfaces contain the same kinds of information.

Gibson rejects behaviorism for a view that animals sample information from the world.

This information contains "optical flow" and this flow contains "affordances"

affordances provide opportunity for action. Here are some affordances for cultured humans.

what would bats make of them?

can we make a catalog of affordances for bats?

can we make another catalog of the artifacts of bat perception?

1. squeaky sounds
2. large ears
3. can "see" in the dark
4. quick wheeling flight

demonstration 1

a volunteer wraps his eyes in a sweater. we turn him around to disorient him. then I point him towards the glass wall. his job is to stop at an arm's length away from the wall. he makes pinging sounds as he goes and gets withing 18" of the wall--closer than he expected.

demonstration 2

a second volunteer sits in a chair. we cover her eyes. a third volunteer holds up a metal-cased laptop computer. the second volunteer is asked to try and point to the reflective surface of the computer. she does so without trouble at distances of up to three feet.

demonstration 3

a third volunteer sits in a chair. a very quiet fourth volunteer circles him. his job is to point to the gap in the sound -- assuming that the person's body will absorb sound in the room. this proves difficult.