Surfaces and Essences: Analogy as the Fuel and Fire of Thinking (17 page)

This phenomenon can affect the difficulty one has in understanding a sentence inside a passage that one has been asked to read. Thus, it turns out that the time taken to read and understand a sentence such as “The bird was now just a few yards away” depends on whether, earlier in the passage, there was a reference to an ostrich (an atypical bird) or to a pigeon (a typical bird), in preparatory sentences such as “The ostrich was approaching” or “The pigeon was approaching”. The link in memory between
ostrich
and
bird
turns out to be less strong than that between
pigeon
and
bird
, and this tends to impair the understanding of the passage in the first case.

It’s important to point out that categorization goes well beyond the intellectual realm of connections among words, which is to say, the names of various categories (such as “sparrow”, “ostrich”, and “bird”). If, for example, someone were to ask Eleanor “Is a spider an insect?”, she might well reply, on the basis of her knowledge from books, “No”, and yet if she were to espy a dark blob hanging from the ceiling of her bedroom, it is likely that she would cry out, “Yikes! Get it out of here! I hate insects in my room — they’re scary!” If someone were to object to her word choice, Eleanor would say that she knows very well that the “insect” was in fact not an insect but a spider.

Generally speaking, context has a great influence on categorization. The spider in this anecdote was seen as an
insect
in the bedroom, but it would not have been seen as such in the context of a biology test, for instance. And much the same holds in general: a single item in the world belongs to thousands of categories, which can be extremely different from each other, and a good fraction of our mental life consists in placing entities in one category and then in reassigning them to another category. During a basketball game, everyone is aware of the fact that basketballs roll, but it has been experimentally shown that only situations that involve water (such as the loading of a bunch of basketballs on board a ship) evoke the notion that basketballs float.

Context thus changes categorization and can modify how we perceive even the most familiar of items. For example, an object can slip in the blink of an eye from the category
chair
to that of
stool
when a light bulb has just burned out and one needs something to stand on in order to change it. Usually one is unaware of these category shifts because one is mentally immersed in a specific context and such shifts are carried out in a totally unconscious manner. In a given context, just one categorization seems possible to most people. Their lack of awareness of the contextual blinders that they are wearing reinforces the widespread belief in a world in which every object belongs to one and only one Platonic category — its “true” category.

On the other hand, one cannot help but recognize how complex category membership is if one considers the fact that a single entity can easily belong to many diverse categories, such as, for instance:

To be sure, this is but a small excerpt from a much longer list one could draw up, a list having essentially no end, and whose entries would all be terms that anyone and everyone would, without any trouble, recognize as designating various categories.

When Ann had to be hospitalized on an emergency basis and a transfusion was needed, her membership in the category
blood-type A+
dominated all her other category memberships, but in a restaurant she is above all a
vegetarian
, while at work she is a
lawyer
, at home a
mother
, in a PTA meeting a
parents’ representative
, and so forth. It may seem useless to point out such obvious facts, but such simple observations carry one well outside the realm of classical categories.

Let’s come back to the one-word category
bird
, which still has some lessons to teach us. Consider the following candidates for membership in the category:

• a bat;

• an airplane;

• a bronze seagull;

• an eagle in a photograph;

• the shadow of a vulture in the sky;

• Tweety the (cartoon-inhabiting) canary;

• an entire avian species, such as
eagle
or
robin
;

• a chick inside an egg two hours before it hatches;

• a flying dinosaur (or rather, a dinosaur that once flew);

• a pigeon on the screen in a showing of Hitchcock’s film
The Birds
;

• the song of a nightingale recorded and played back fifty years after it died;

• a rubber-band-powered wing-flapping plastic object that swoops about in the air.

If you are like the vast majority of humans, you probably felt a keen desire to say “yes” or “no” to each of the candidates in the list above, as if you were taking an exam
in school and had to demonstrate the precision of your knowledge, and as if, in each of these cases, there really were a
correct
answer to the question. A sparrow — is it a bird?
Yes!
When you spot a black spot moving unpredictably through the air against a light cloudy background, are you seeing a bird?
Of course!
And when one sees the shadow of a vulture on the ground, is one seeing a bird?
Of course not!
When one hears a loud hooting during the night, is one hearing a bird?
Yes!
And if one hears a recorded hooting (perhaps without being aware that it is recorded)? And what about the case where some person imitates hooting extremely well? And if one dreams about an owl, is there a bird involved? And if one reads a comic book featuring Tweety?

No one ever taught us the boundaries of categories. Our spontaneous sense for their boundaries is an outcome of what we often call “common sense”, and no one teaches that in any school. There are no courses on category membership, and even if there were, there would be endless arguments among the students as well as between teachers and students, not to mention the passionate debates that would take place among the teachers themselves. Indeed, expertise doesn’t help at all. Here we borrow an anecdote from the psychologist Gregory Murphy, who quoted from a keynote speech once delivered by a world-renowned metallurgist at a conference of world experts in that field: “I’ll tell you something. You really don’t know what a metal is. And there is a big group of people that don’t know what a metal is. Do you know what we call them?
Metallurgists!
”

The recent vehement debates among astronomers over whether Pluto should or should not be deemed a planet (which, as of this writing, it no longer officially is) were due to the blurriness of the concept of
planet
, even in the minds of this planet’s greatest specialists, which made the question extremely thorny. For similar reasons, although there is considerable agreement among experts today that it is not correct to refer to our “five senses”, since proprioception, thermoception, and nociception (among others) would be left out of such a roll call, there remains a major blur about what our senses really are. Since the experts can’t even agree on how many senses we have, let alone on what they all are, they often talk about “our five main senses”. And in a similar vein, a standard definition of
life
is still missing, even if biologists, hoping to pin it down for once and for all, are constantly juggling the details of taxonomies that laypersons would have presumed had long ago been cast in concrete. The classification of living organisms has come a long way since Linnæus, and today, many classic terms that he employed in his classification, such as “reptile”, “fish”, and “algæ”, remain present in school texts, but no longer appear in modern phylogenetic classifications. All this goes to show that the blur of categories is not due to some kind of lack of expertise, but is part and parcel of the act of categorization.

Although psychologists have done a good job in making it clear that no category has precise boundaries, our everyday language and thought are still permeated with residual traces of the classic vision in which category boundaries are as sharp as those of
nations (which, to be sure, are often not all that clear, but we’ll leave that matter aside). Our intense human desire to avoid ambiguity, to pinpoint the true and to discard the false, to separate the wheat from the chaff, tends to make us seek and believe in very sharp answers to questions that have none.

For instance, people who enjoy studying foreign languages are frequently asked the question, “How many languages do you speak?” Despite how perfectly natural this question might seem, it is based on the tacit idea that the languages of the world fall into two precise bins: languages that person X
does
speak, and languages that X does
not
speak, as if this were a black-and-white matter. But in fact, for each language one has studied, one speaks it to a different degree, depending on many factors, such as when one first studied it, the context in which one studied it, how long it has been since one spoke it, and so forth. When pressed, the questioner may retreat, saying, “All I meant was, ‘How many languages can you have an everyday conversation in?’ ”

But once again, even if this new question sounds reasonable at first, it’s just as blurry. For example, it presumes that the category
everyday conversation
is sharp and well-defined. But it might mean a conversation of two minutes about the cost of postage stamps with someone standing next to one in a line in the post office. Or it might mean a half-hour conversation about one’s children and family, or about the World Series, or about the sad state of the world economy, with a stranger sitting next to one in an airplane. Then again, it might mean a three-hour conversation ranging over twenty different random topics with seven other people, all native speakers, seated around the table at a lively dinner party. Most people say they speak a language when they have surpassed a far lower threshold than that, but in any case, the threshold for “speaking a language” is not well-defined.

And indeed, the category
language
is itself very blurry. How many languages are spoken in a polyglot land such as India, China, or Italy? In each case, there are many languages and dialects; moreover, what is the precise distinction between a
dialect
and a
language
? The following humorous observation is often attributed to the linguist Max Weinreich: “A language is a dialect with an army”, and there is much truth to it, but it still begs the question; after all, what exactly constitutes an army?

In short, the question “How many languages do you speak?” is not a simple question, and has no simple answer — no more so than do the questions “How many sports do you play?”, “How many movies do you love?”, “How many soups do you know how to make?”, “How many big cities have you lived in?”, “How many friends do you have?”, or “How many things have you done today?”

Psychological studies have shown that a mental category, rather than having well-defined and context-independent boundaries, is more like a vast cosmopolitan area such as Paris, which first sees the light of day as a tiny, almost solid, central core (and which, as time passes, will eventually be baptized the “old town”, and which shortly after its birth might well have had walls defining its boundary). The “old town” is the
original core from a historical standpoint, but the core can move over time and today it may contain modern buildings and roads. After all, both metropolises and categories evolve; it’s part of their natural developmental process. Both metropolises and categories exhibit a structure that is the result of repeated acts of extension, and in the case of categories, each new extension is due to some perceived analogy. At every moment in the life of a major metropolis or a “mature” category, there is a crucial, central zone that includes, surrounds, and dominates over the original core, and this zone is considered the town’s (or category’s) essence. Further out, one finds an urban ring that is not as dense or as historically important, and then there comes a vast suburban ring, which extends far out from the center while growing gradually less and less densely populated, and which has no precise outermost boundary. Nonetheless, one has a pretty clear sense for when one has gone beyond the edge of the metropolitan area, since fields filled with wheat and cattle are evidently no longer part of a city.

In our analogy, the suburban sprawl corresponds to the most recent, fresh, novel, creative usages of the word, which still strike us as metaphorical. And yet over time, these usages, if they resonate with native speakers, will become so widespread and bland that after a while no one will hear them as metaphors any longer. This is essentially what happened to yesterday’s suburbs, which today strike us as essential parts of the city, so much so that we have great difficulty imagining how the city ever could have been otherwise.