## The Overview Effect and Intuitive Tractability

### 26 March 2017

Sunday

Looking down on Earth from above may not only make us reevaluate out relationship to the planet, but may also help us to understand the planet better.

Science is a way to better understand the world, but science itself is not always easy to understand, and we often find that, after clarifying some problem through science, we must then clarify the science so that the science makes sense to us. Some call this science communication; I call it the pursuit of intuitive tractability.

While it is not part of science proper to seek intuitively tractable formulations, it is part of human nature to seek intuitively tractable formulations, as we are more satisfied with science formulated in intuitively tractable forms than with science that is not intuitively tractable. For example, there is, as yet, no intuitively tractable formulation of quantum theory, and this may be why Einstein famously wrote in a letter to Max Born that, “Quantum Mechanics is very impressive. But an inner voice tells me that it is not yet the real thing.”

When the concept of zero was introduced into mathematics, it was thought to be an advanced and difficult idea, but we now teach a number system starting with zero to children in primary school. In a similar way, the Hindu-Arabic system of numbers has displaced almost every other system of numbers because it is what I would paradoxically call an intuitive formalism, i.e., it is a formalization of the number concept that is both adequate to mathematics and closely follows our intuitive conception of number. Mathematics is easier with Hindu-Arabic numerals than other numbering systems because this numbering system is intuitively tractable. There are other formalisms for number that are equally valid and equally correct, but not as intuitively tractable.

The pursuit of intuitive tractability has also been evident in geometry, and especially the axiomatic exposition of geometry that begins with postulates accepted ab initio as self-evident, and which has been the model of rigorous mathematics ever since Euclid. Euclid’s fifth postulate, the famous parallel postulate, is difficult to understand and was a theoretical problem for geometry until its independence was proved, but whether or not the fifth postulate was demonstrably independent of the other postulates, Euclid’s opaque exposition did not help. Here is Euclid’s parallel axiom from the Elements:

“If a line segment intersects two straight lines forming two interior angles on the same side that sum to less than two right angles, then the two lines, if extended indefinitely, meet on that side on which the angles sum to less than two right angles.”

Almost two thousand years later, in 1846, John Playfair formulated what we now call “Playfair’s axiom,” which tells us everything that Euclid’s postulate sought to communicate, but in a far more intuitively tractable form: “In a plane, given a line and a point not on it, at most one line parallel to the given line can be drawn through the point.” Once this more intuitively tractable formulation of the parallel postulate was available, Euclid’s formulation was largely abandoned. There is, then, a process of cognitive selection, whereby the most intuitively tractable formulations are preserved and the less intuitively tractable formulations are abandoned.

Those concepts that are the most intuitively tractable are those concepts that are familiar to us all and which are seamlessly integrated into ordinary thought and language. I have called such concepts “folk concepts.” Folk concepts that have persisted from their origins in our earliest evolutionary psychology up into the present have been subjected to the cognitive equivalent of natural selection, so that we can reasonably speak of folk concepts as having been refined and elaborated by the experience of many generations.

In a series of posts — Folk Astrobiology, Folk Concepts of Scientific Civilization, and Folk Concepts and Scientific Progress — I have considered the nature of “folk” concepts as they have been frequently invoked, and it is natural to ask, in the light of such an inquiry, whether there is a “folk Weltanschauung” that is constituted by a cluster of folk concepts that naturally hang together, and which inform the pre-scientific (or non-scientific) way of thinking about the world.

Arguably, the idea of a folk Weltanschauung is already familiar by a number of different terms that philosophers have employed to identify the concept (or something like the concept) — naïve realism or common sense realism, for example. What Husserl called “natürliche Einstellung” and which Boyce Gibson translated as “natural standpoint” and Fred Kersten translated as “natural attitude” could be said to approximate a folk Weltanschauung. Here is how Husserl describes the natürliche Einstellung:

“I am conscious of a world endlessly spread out in space, endlessly becoming and having endlessly become in time. I am conscious of it: that signifies, above all, that intuitively I find it immediately, that I experience it. By my seeing, touching, hearing, and so forth, and in the different modes of sensuous perception, corporeal physical things with some spatial distribution or other are simply there for me, ‘on hand’ in the literal or the figurative sense, whether or not I am particularly heedful of them and busied with them in my considering, thinking, feeling, or willing.”

Edmund Husserl, Ideas Pertaining to a Pure Phenomenology and to a Phenomenological Philosophy: First Book: General Introduction to a Pure Phenomenology, translated by Fred Kersten, section 27

Husserl characterizes the natural attitude as a “thesis” — a thesis consisting of a series of posits of the unproblematic existence of ordinary objects — that can be suspended, set aside, as it were, by the phenomenological procedure of “bracketing.” These posits could be identified with folk concepts, making the thesis of the natural standpoint into a folk Weltanschauung, but I think this interpretation is a bit forced and not exactly what Husserl had in mind.

Perhaps closer to what I am getting at than the Husserlian natural attitude is what Wilfrid Sellars has called the manifest image of man-in-the-world, or simply the manifest image. Sellars’ thought is no easier to get a handle on than Husserl’s thought, so that one never quite knows if one has gotten it right, and one can easily imagine being lectured by a specialist in the inadequacies of one’s interpretation. Nevertheless, I think that Sellers’ manifest image is closer to what I am trying to get at than Husserl’s natürliche Einstellung. Closer, but still not the same.

Sellars develops the idea of the manifest image in contrast to the scientific image, and this distinction is especially given exposition in his essay Philosophy and the Scientific Image of Man. After initially characterizing the philosophical quest such that, “[i]t is… the ‘eye on the whole’ which distinguishes the philosophical enterprise,” and distinguishing several different senses in which philosophy could be said to be a synoptic effort at understanding the world as a whole, Sellars introduces terms for contrasting two distinct ways of seeing the world whole:

“…the philosopher is confronted not by one complex many dimensional picture, the unity of which, such as it is, he must come to appreciate; but by two pictures of essentially the same order of complexity, each of which purports to be a complete picture of man-in-the-world, and which, after separate scrutiny, he must fuse into one vision. Let me refer to these two perspectives, respectively, as the manifest and the scientific images of man-in-the-world.”

Wilfrid Sellars, Philosophy and the Scientific Image of Man, section 1

Sellars’ distinction between the manifest image and the scientific image has been quite influential. A special issue of the journal Humana Mente, Between Two Images: The Manifest and Scientific Conceptions of the Human Being, 50 Years On, focused on the two images. Bas C. van Fraassen in particular has written a lot about Sellars, devoting an entire book to one of the two images, The Scientific Image, and has also written several relevant papers, such as “On the Radical Incompleteness of the Manifest Image” (Proceedings of the Biennial Meeting of the Philosophy of Science Association,Vol. 1976, Volume Two: Symposia and Invited Papers 1976, pp. 335-343). All of this material is well worth reading.

Sellars is at pains to point out that his distinction between manifest image and scientific image is not intended to be a distinction between pre-scientific and scientific worldviews (“…what I mean by the manifest image is a refinement or sophistication of what might be called the ‘original’ image…”), though it is clear from this exposition that the manifest image, however refined and up-to-date, has its origins in a pre-scientific conception of the world. (“It is, first, the framework in terms of which man came to be aware of himself as man-in-the-world.”) The essence of this distinction between the manifest image and the scientific image is that the manifest image is correlational while the scientific image is postulational. What this means is that the manifest image “explains” the world (in so far as it could be said to explain the world at all) by correlations among observables, while the scientific image explains the world by positing unobservables that connect observables “under the surface” of things, as it were (involving, “…the postulation of imperceptible entities”). Sellars also maintains that the manifest image cannot postulate in this way, and therefore cannot be improved or refined by science, although it can improve on itself by its own correlational methods.

I do not yet understand Sellars well enough to say why he insists that the manifest image cannot incorporate insights from the scientific image, and this is a key point of divergence between Sellars’ manifest image and what I above called a folk Weltanschauung. If a folk Weltanschauung consists of a cluster of tightly-coupled folk concepts (and perhaps a wide penumbra of associated but loosely-coupled folk concepts), then the generation of refined scientific concepts can slowly, one-by-one, replace folk concepts, so that the folk Weltanschauung gradually evolves into a more scientific Weltanschauung, even if it is not entirely transformed under the influence of scientific concepts. Science, too, consists of a cluster of tightly-coupled concepts, and these two distinct clusters of concepts — the folk and the scientific — might well resist mixing for a time, but the human mind cannot keep such matters rigorously separate, and it is inevitable that each will bleed over into the other. Sometimes this “bleeding over” is intentional, as when science reaches for metaphors or non-scientific language as a way to make its findings understood to a wider audience. This is part of the pursuit of intuitively tractable formulations, but it can also go very wrong, as when scientists adopt theological language in an attempt at a popular exposition that will not be rejected out-of-hand by the Great Unwashed.

Despite my differences with Sellars, I am going to here adopt his terminology of the manifest image and the scientific image, and I will hope that I don’t make too much of a mess of it. I will have more to say on this use of Sellars’ concepts below (especially in relation to the postulational character of the scientific image). In the meantime, I want to use Sellars’ concepts in a exposition of intuitive tractability. Sellars’ uses the metaphor of “stereoscopic vision” as the proper way to understand how we must bring together the manifest image and the scientific image as a single way of understanding the world (“…the most appropriate analogy is stereoscopic vision, where two differing perspectives on a landscape are fused into one coherent experience”). I think, on the contrary, that intuitively tractable formulations of scientific concepts can make the manifest image and the scientific image coincide, so that they are one and the same, and not two distinct images fused together. A slightly weaker formulation of this is to assert that intuitively tractable formulations allow us to integrate the manifest image and the scientific image.

Now I want to illustrate this by reference to the overview effect, that is to say, the cognitive effect of seeing our planet whole — preferably from orbit, but, if not from orbit, in photographs and film that make the point as unmistakably as though one were there, in orbit, seeing it with one’s own eyes.

Before the overview effect, we saw our planet with the same eyes, but even after it is proved to us that the planet is (roughly) a sphere, hanging suspended in space, it is difficult to believe this. All manner of scientific proofs of the world as a spherical planet can be adduced, but the science lacks intuitive tractability and we have a difficult time bringing together our scientific concepts and our folk concepts of the world — or, if you will, we have difficulty reconciling the manifest image and the scientific image. The two are distinct. Until we achieve the overview effect, there is an apparent contradiction between what we experience of the world and our scientific knowledge of the world. Our senses tell us that the world is flat and solid and unmoving; scientific knowledge tells us that the world is round and moving and hanging in space.

Once we attain the overview effect, this changes, and the apparent contradiction is revealed as apparent. The overview effect shows how the manifest image and the scientific image coincide. The things we know about ordinary objects, which shapes the manifest image, now applies to Earth, which is seen as an object rather than as surrounding us as an environment with an horizon that we can never reach, and which therefore feels endless to us. Seen from orbit, this explains itself intuitively, and an explicit explanation now appears superfluous (as is ideally the case with an axiom — it is seen to be true as soon as it is understood). The overview effect makes the scientific knowledge of our planet as a planet intuitively tractable, transforming scientific truths into visceral truths. One might say that the overview effect is the lived experience of the scientific truth of our homeworld. In this particular case, we have replaced a folk concept with a scientific concept, and the scientific concept is correct even as intuition is satisfied.

The use of the overview effect to illustrate the manifest and scientific images, and their possible coincidence in a single experience, is especially interesting in light of Sellars’ insistence that the scientific image is distinctive because it is postulational, and more particularly that it postulates unobservables as a way to explain observables. When, in a scientific context, someone speaks of unobservables or “imperceptible entities” the assumption is that we are talking about entities that are too small to see with the naked eye. The germ theory of disease and the atomic theory of matter both exemplify this idea of unobservables being observable because they are smaller than the resolution of unaided human vision. We can only observe these unobservables with instruments, and then this experience is mediated by complex instruments and an even more complex conceptual framework so that no one ever speaks of the “lived experience” of particle physics or microbiology.

In contrast to this, the Earth is unobservable to the human eye not because it is too small, but because it is too large. When shown scientific demonstrations that the world is round, we must posit an unobservable planet, and then identify this unobservable entity with the actual ground under our feet. This is difficult to do, intuitively speaking. We see the world at all times, but we do not see it as a planet. We do not see enough of the world at any one moment to see it as a planet. Enter the overview effect. Seeing the Earth whole from space reveals the entity that is planet Earth, and if one has the good fortune to lift off from Earth and experience the process of departing from its surface to then see the same from space, this makes a previously unobservable postulate into a concretely experienced entity.

We are in the same position now vis-à-vis our place within the Milky Way galaxy, and our place within the larger universe, as we were once in relation to the spherical Earth. Our accumulated scientific knowledge tells us where we are at in the universe, and where we are at in the Milky Way. We can even see a portion of the Milky Way when we look up into the night sky, but we cannot stand back and see the whole from a distance, taking in the Milky Way and pointing of the position of our solar system within one of the spiral arms of our galaxy. We know it, but we haven’t yet experienced it viscerally. We have to posit the Milky Way galaxy as a whole, the Virgo supercluster, and the filaments of galaxies that stretch through the cosmos, because they are too large for us to observe at present. They are partially observed, in the way we might say that an atom is partially observed when we look at a piece of ordinary material composed of atoms.

Our postulational scientific image of the universe in which we live is redeemed for intuition by experiences that put us in a position to view these entities with our own eyes, and so to see them in an intuitively tractable manner. Perhaps one of the reasons that quantum theory remains intuitively intractable is that the unobservables that it posits are so small that we have no hope of ever seeing them, even with an electron microscope.

Ultimately, intuitively tractable formulations of formerly difficult if not opaque scientific ideas is a function of the conceptual framework that we employ, and this is ultimately a philosophical concern. Sellars suggests that the manifest and scientific conceptual framework might be harmonized in stereoscopic vision, but he doesn’t hold out any hope that the manifest image can be integrated with the scientific image. I think that the example of the overview effect demonstrates that there are at least some cases when manifest image and scientific image can be shown to coincide, and therefore these two ways of grasping the world are not entirely alien from each other. Cosmology may be the point of contact at which the two images coincide and through which the two images can communicate.

The pursuit of intuitive tractability is, I submit, a central concern of scientific civilization. If there ever is to be a fully scientific civilization, in which scientific ways of knowing and scientific approaches to problems and their solutions are the pervasively held view, this scientific civilization will come about because we have been successful in our pursuit of intuitive tractability, and we are able to make advanced scientific concepts as familiar as the idea of zero is now familiar to us. Since the question of a conceptual framework in which rigorous science and intuitively tractable concepts can be brought together is not a scientific question, but a philosophical question, the contemporary contempt for philosophy in the special sciences is invidious to the effective pursuit of intuitive tractability. The fate of scientific civilization lies with philosophy.

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Overview Effects

The Overview Effect and Intuitive Tractability

Homeworld Effects

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