Whoever sees the web of cause and effect, sees the Way.
—THE PĀLI CANON,
The Great Elephant Footprint Sutra
(committed to writing in 29 B.C.E.)
Happy is he who was able to know the causes of things.
—VIRGIL,
Georgics
(29 B.C.E., book II, line 490)
The Web of Cause and Effect
The computational chores that babies face in mapping the labyrinth of language in the middle of which they find themselves upon arrival are closely related to the broader cognitive task of learning the ways of the world, of which language, as Borges would put it, is an incomplete, but not false, image. To see how well language fits within the rest of cognition, ask yourself, “Where is this paragraph going and what does it mean?” and then substitute “situation” for “paragraph.” (This far into the book, I bet you have a reasonably good idea where my paragraphs go, given how well you have mastered the science of reading my mind.)
Both in language and in cognition in general, mastery comes down to the same two abilities: first,
understanding
the world by seeking patterns in sensorimotor activity and learning to relate them to a wider context, including your own and other people’s experiences and mind processes; and second, using understanding to support
foresight
. The big picture is in fact even simpler than that: understanding and foresight are really two sides of the same coin, because they both hinge on knowledge of the causal structure of the world.
In language, this knowledge allows a person to process an utterance so as to yield some clues regarding the state of affairs of the world, including the utterer’s beliefs and intentions, and, in due course, to process one’s own intentions so as to yield a plan for generating an intelligible sequence of vocal and/or other gestures. The mechanisms of language learning keep tabs on experience, seeking to distill from it causal patterns of dependencies, such as the effects of discourse and situational context on construction choice and sequencing. These mechanisms build on more general cognitive capabilities that seek patterns in episodic memories. The knowledge of language, or grammar, is thus part of a wider web of cause and effect linking people and situations, and so ultimately is a part of the code of conduct of the world at large.
1
Through a Scanner, Darkly
To yield meaning, the raw stream of ongoing experience, along with episodic memories of the past, must be searched for statistically reliable patterns. Like ripples on the surface of a pond haunted by a school of koi, these patterns arise from objects that are immersed in the world; a particularly perceptive frog sitting on a lily pad and watching the water surface could perhaps infer the koi’s presence and learn about their movements.
2
Some such patterns are relational in that they depend less on what the objects are and more on what events they participate in and on how these unfold in time: to a koi watching from below, the pattern created by a pebble skimmed off the water surface would appear very similar to the ripples produced by a skillfully aimed small frog.
Once learned, patterns that are characteristic of objects and events become the nodes and the links in the mind’s representation of the world-wide web of cause and effect. Far from being a mere record of experience, this representation brings out the regularities in it, which alone afford understanding and foresight. Whereas any singular experience, in every respect unlike anything you ever encountered, is an absolute mystery, two of a kind are a revelation that may help you prepare for a third. Having evolved in an unforgiving world that often enough is also just so partially predictable, we are geared toward perceiving and thinking in terms of generalizable patterns of information, or
concepts
.
3
It is frustratingly difficult to explain the concept of “concept” by offering and discussing examples—not because examples of concepts are scarce, but rather because concepts are an integral part both of the process of explanation and of its intended product, comprehension. This quandary stretches from the loftiest realms of abstract cognition, where one hopes against hope that language-mediated conceptual inquiry can resolve conundra of its own making—such as “What is truth?”—to the most concrete concepts that seem to be directly and immediately grasped by the senses, such as a straight line or an ascending tonal sequence.
I figure that the concept-ladenness of abstractions such as “truth” (let alone “concept”) is pretty obvious as it is, so let us focus on concrete stuff—say, a thin straight line traced with a sharp pencil on a wide expanse of white paper. The hard fact of the matter is this: nowhere in the brain’s visual pathways is the representation of this line thin, or straight. To begin with, its projection onto the retina, which conforms to the inner surface of the eyeball, is curved. This arc-like retinal image is sampled by an array of photoreceptors, which are tightly packed into a mosaic that is locally roughly hexagonal, but otherwise irregular. Within this array, the set of receptors that actually respond to the line—more vigorously, or less so, depending on how close the receptor is to the center of the line’s retinal “footprint”—is shaped like a banana.
A couple of intra-retinal processing stages later, the eye’s million-dimensional output representation space is defined by the axons that form the optic nerve, one dimension per axon. Applying the no. 4 conceptual tool from Chapter 3, we recall that in this space the line is represented by a single point. The computational problem faced by the rest of the brain—to determine, without outside help, that this point in the representation space stands for a straight line “out there” in the visible world—may not be very difficult, but it is not trivial either, and its very existence suggests that perception, even of the simplest imaginable stimuli, is never simple or direct.
4
The collective, distributed computations through which visual concepts are related to the outside world need to be calibrated and maintained. The brain does it by continually adding lessons from its ongoing experience to the pool of statistical knowledge that embodies each concept. Statistically speaking, a straight line is the average of a population of lines that curve in opposite directions. Evidence that the brain maintains this average dynamically and uses it to calibrate its perception of straightness comes from studies in which people are asked to wear prismatic goggles that distort the perceived environment by causing straight edges to appear curved to one side. After a period of adaptation, the subjects cease perceiving the curvature, at which point the goggles are removed and the opposite effect emerges: they now see straight edges as curving to the opposite side. This and many other findings show that perception is
situated
—rather than dealing in universals, it is attuned to certain collective properties of the particulars of the perceiver’s environment.
5
In its constant strain to stay calibrated, the brain responds not only to the statistics of perceived external stimuli but also to the many internal status indicators generated by the body that it helps to control. Thus, hikers facing a hill see it as quantifiably and significantly steeper if they are carrying heavy backpacks or are hungry, compared to the perceptions of unencumbered subjects who just finished a nice breakfast. When examined in this manner, the mind is revealed to be thoroughly
embodied
. Even the highest-level cognitive functions are affected, as are emotions—processes that compute and broadcast cues that modulate the rest of cognition. Nod your head as in agreement while listening to a sales pitch and your attitude toward its message will be more positive than if you shake your head as in disagreement; hold a pencil sideways between your teeth so as to stretch your face into a semblance of a smile, and you’ll find a joke that’s being told to you funnier than if you hold it in your mouth as you would a cigar. It seems that any conceivable claim regarding how bodily states may affect mind states turns out to have some substance to it, if only one cares to investigate.
6
The two complementary principles of cognition that I just sketched, situatedness and embodiment, demonstrate how the virtual computational construct that is the human mind is rooted in the human brain, body, and environment. This new understanding elaborates upon the by now familiar notion that the world we perceive is virtual by explicating the nature of concepts—the computational processes and representations that give rise to our perception of reality. As expected from a complex statistical computation, this perception may or may not be veridical, depending on the task and the situation .
7
Because of the unavoidable uncertainty and the occasional outright distortions (some going unnoticed, others revealed as perceptual illusions), conceptual structures are sometimes described metaphorically as a prism through which one perceives reality. We now know enough about the nature of minds and their embodiment to realize that this metaphor is grossly misleading. There is no functional counterpart in the brain to a looking glass or a scanner that is separate from the self that sees through it, just as there is no divide between the self and its past interactions with the world. Had I been born with a different kind of perceptual system in place, or had my subsequent experiences been radically different, I would have been a different person now.
Because It’s There
Many of the representations at the mind’s thinking “core” are active processes that are constantly on the lookout for grist for their computational mills: perceived environmental affordances; episodic memories; bits and pieces of presently applicable more or less general knowledge; inner motives and drives; and whatnot. The products of their computations are turned into more memories and more knowledge and sometimes bring about overt action. Because actions have consequences, this thinking core strives at all times to perceive the world (and itself, when it turns its gaze inward) not as a random assemblage of informational odds and ends but as a meaningful web of cause and effect. Because of that, and to distinguish it from other components of what I am, I shall call this part of my mind the
effective Self
.
Although it goes a long way toward defining my unique personality, the effective Self is not confined to my skull, for the simple reason that the concepts represented internally within my brain are hopelessly entangled, in the cause-and-effect sense, with outside objects and events. Because external objects are the causes behind their internal conceptual representations (mediated by the clusters of sensory and relational features that the concepts account for), they are poised to contribute significantly to the determination of behavior. Speaking for myself, I can observe, for instance, that a significant (albeit by no means exclusive) determinant of my behavior is a geological formation in faraway California: Death Valley.
I had always been strongly attracted to the peace and solitude of desert landscapes, but assorted obligations and the logistics of getting to a desert from the all too civilized parts where I live used to keep me from hiking as much as I would have liked to. Finally, a few winters ago, I decided that the following March I would set aside all other plans for a week, fly to Death Valley, and go hiking. Since then, several times every year I disappear into one of the great deserts of the Southwest for a few days at a time.
Don’t be misled by the conventional phrasing of my description of the decision process in the preceding paragraph (“I decided . . . ”). In truth, the “I” who made the decision includes a chunk of California wilderness. Were it not there, the world would have been a noticeably duller place, and my plans for the following March would have been different. (This observation singles out a sense in which George Mallory’s stated reason for climbing Mt. Everest—“because it’s there”—is literally true.)
On a less far-out but equally important note, my effective Self also maintains a bidirectional (albeit far from symmetrical) causal interconnection with the university that is my present employer: were it not for the spring break that it offers its students, in March I would be teaching in Ithaca, New York, not hiking around Panamint Springs, California. And, closer to home, a far stronger connection links my own Self with that of my wife, who cheerfully tolerates my wilderness walkabouts, if only because causation in this case runs both ways: I am a part of her just as she is a part of me.
Catching up with certain long-standing poetical views of the nature of the Self, cognitive psychology is opening up more and more to the idea of the intermingling of selves as an explanatory device both for falling in love and for staying there. On this account, the melding of the selves of long-wed spouses is merely an extreme case of the common crossing-over of trajectories of cause and effect between the brains of people who are open to each other. This latest news from the psychology of love would have pleased John Donne, in one of whose epithalamions we find this line: “You, and your other you, meet there anon.”
8
Connecting the Dots
The brain’s compulsion to seek patterns of causation applies most strongly to observed outside data. It is undaunted by the fundamental lack of certainty in inferring causation from correlation, settling instead for likelihood. On a moment-by-moment basis, a strong illusion of causality ensues from uncanny coincidences in which one event follows another in close succession. If a mug sitting on the edge of my desk falls off and shatters as soon as I point a wand at it and mumble a spell, you’re bound to feel that magic is afoot, even if rational inquiry reveals alternative explanations (such as a trick with a piece of fishing line) that are more plausible.