The Transplanetary Perspective

Saturday

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Though I’ve already written a longish post on the relationships among earth sciences, planetary sciences, and space sciences, and I feel that a definitive formulation of this relationship continues to elude me, so I continue to write about it and think about it, in the hope that this exercise in self-clarification will eventually culminate in a more-or-less satisfying account. Or maybe not. But I will continue to think about it nonetheless, and I take a keen interest in the steady stream of new findings in planetary sciences, such as in Newborn Star Study Reveals Never-Before-Seen Stage Of Planet Birth and The Primordial Star at the Edge of the Milky Way that Shouldn’t Exist Challenges Theories of Star Formation.

Part of the difficulty is that the earth sciences, planetary sciences, and space sciences, while all having roots that go back to the very beginnings of human scientific inquiry, are relatively recent in their current incarnations, and any distinctions among them are similarly recent. Also, all sciences begin on the earth (what I will below call “earth-originating”), and all natural sciences begin, in a sense, as earth sciences, because human civilization and the science it produces originates on the earth, so that there is an inherent ambiguity once these earth-originating sciences are extrapolated beyond the earth to other celestial bodies (moons, planetesimals, etc.), other planets in our solar systems, other solar systems around other stars, other star systems in other galaxies, and so on.

What does Michel Foucault have to do with planetary science?

There is a quote from Foucault that I have cited on several occasions that is (partially) relevant here:

Each of my works is a part of my own biography. For one or another reason I had the occasion to feel and live those things. To take a simple example, I used to work in a psychiatric hospital in the 1950s. After having studied philosophy, I wanted to see what madness was: I had been mad enough to study reason; I was reasonable enough to study madness. I was free to move from the patients to the attendants, for I had no precise role. It was the time of the blooming of neurosurgery, the beginning of psychopharmacology, the reign of the traditional institution. At first I accepted things as necessary, but then after three months (I am slow-minded!), I asked, “What is the necessity of these things?” After three years I left the job and went to Sweden in great personal discomfort and started to write a history of these practices. Madness and Civilization was intended to be a first volume. I like to write first volumes, and I hate to write second ones. It was perceived as a psychiatricide, but it was a description from history. You know the difference between a real science and a pseudoscience? A real science recognizes and accepts its own history without feeling attacked. When you tell a psychiatrist his mental institution came from the lazar house, he becomes infuriated.

Truth, Power, Self: An Interview with Michel Foucault — October 25th, 1982, Martin, L. H. et al (1988) Technologies of the Self: A Seminar with Michel Foucault, London: Tavistock. pp.9-15

The portion of the above most often quoted out of context is this:

You know the difference between a real science and a pseudoscience? A real science recognizes and accepts its own history without feeling attacked.

Far from the earth sciences, planetary sciences, and space sciences (or, rather, their predecessors) constituting pseudo-sciences, they are the very standard by which we ought to judge “hard” natural sciences, but as earth-originating sciences are extrapolated beyond the earth there may be an intellectual tension (hopefully, a creative tension) between the earth-specific forms of earth-originating sciences, and the generalized forms that these sciences take when earth-originating sciences are applied to other planets. I don’t think that planetary sciences and space sciences will feel “attacked” by their earth-originating predecessors, but the tendency to specialization in the most advanced natural sciences may well lead to territoriality among disciplines. This would be regrettable.

The generalization of earth-originating sciences into non-earth-specific planetary sciences and space science will be a necessary prerequisite to the long term growth of human civilization. A future interstellar civilization will be intensely interested in where in the galaxy valuable resources are to be found, in the same way that our planetary-based (and, currently, planetary-bound) civilization is intensely interested in the distribution of mineral resources under the surface of the earth. Much of the contemporary relationship between science and industry stems from this need for resources to fuel the fires of industry. (In this connection I urge the reader to consult the excellent book by Simon Winchester, The Map That Changed the World: William Smith and the Birth of Modern Geology, which traces the development of the first geophysical map of England to the search for coal seams.)

What coal and oil have been to planetary civilization, titanium and fissionables (inter alia) will be to interplanetary and interstellar civilization; and the role that coal and petroleum geology have played in the exploitation of coal and oil for planetary civilization will have their parallel in the role that planetary sciences and space sciences will have in the exploitation of resources necessary to interplanetary and interstellar civilization. To grow as a civilization, therefore, we need to adopt a transplanetary perspective in our sciences. This is already occurring.

Planetary formation must ultimately be understood in the context of stellar formation, since stars and planets ultimately coalesce from the same disc of gas and dust, and stellar formation must ultimately be understood in the context of galactic formation, since stars coalesce from the matter that swirls together as galaxies, and galactic formation must ultimately be understood in the context of the formation of galactic clouds, clusters, and superclusters, etc. In short, the entire structure of the universe is implicated in the formation of planets, and how we are to distinguish kinds of planets or generations of planets.

Astronomers distinguish between population I stars, population II stars, and population III stars (from youngest to oldest, respectively), based on their generation of enrichment with heavier elements (called the metallicity, or Z, of a star, i.e., its composition in terms of chemical elements other than hydrogen and helium) as a result of the nucleosynthesis of earlier generations of stars. To date, population III stars, hypothetically extremely metal-poor stars from the earliest ages of the universe (coincident with the advent of the stelliferous age and the universe “lighting up” with star light), have been postulated but not observed. However, some recently reported observations (The First Stars of the Universe — Major Discovery Announced by MIT) may be of a population III star.

It is to be expected that each of these populations of stars will have planetary systems typical of for these particular stellar populations (if they have planetary systems at all). If, then, we can refine the astrophysics and cosmology of stellar and planetary formation, breaking down population I stars into a more finely-grained account, perhaps even tracing back individual stars to individual stellar nurseries, it may be possible to determine the likely composition of solar systems (and therefore their resources available for commercial and industrial exploitation) derived from a given stellar nursery. Stars and their planetary systems, where these planetary systems exist, formed from one and the same concentration of gas and dust, so that there is a systematic correlation between the chemical composition of stars and their planetary systems, both in the case of our own solar system and in other solar and planetary systems that science has only recently begun to study. While stars and planets may form at different times and from different portions of a proto-planetary disc, the whole process of stellar and planetary formation constitutes a single natural history of a solar system.

As I noted above, this kind of research is already underway. Robert McGown has directed by attention to the paper Enhanced lithium depletion in Sun-like stars with orbiting planets published in Nature, which the authors conclude with this paragraph:

“It is known that solar-type stars with high metallicity have a high probability of hosting planets. Those solar analogues with low Li content (which is extremely easy to detect with simple spectroscopy) have an even higher probability of hosting exoplanets. Understanding the long-lasting mystery of the low Li abundance in the Sun appears to require proper modelling of the impact of planetary systems on the early evolution of solar analogue stars.”

“Enhanced lithium depletion in Sun-like stars with orbiting planets,” Garik Israelian, Elisa Delgado Mena1, Nuno Santos, Sergio Sousa, Michel Mayor, Stephane Udry, Carolina Domínguez Cerdeña1, Rafael Rebolo1, & Sofia Randich, Nature 462, 189-191 (12 November 2009)

The lithium-planetary system correlation suggests a range of research questions, such as the following: Is the sun especially rich or poor in any other element that might point to the existence or composition of a proto-planetary disc during stellar or planetary formation? Does the chemical composition of the planets of our solar system stand in any systemic or predictive relationship to the chemical composition of our sun as revealed by its spectrum? Does the spectrum of a star predict not only the presence or absence of a planetary system, but also the chemical composition of any planets? Does the chemical composition of planets predict the chemical composition of the stars they orbit?

The lithium-planetary system correlation also suggests research questions bearing upon stars that have no planetary system associated with them. While the technology does not yet exist to study in detail stars without planetary systems, improved telescopy and imaging techniques may provide data for such questions in the not distant future. The most obvious hypotheses to account for stars without associated planetary systems would include isolated stars formed from a proto-stellar mass with nothing left over for planets to form, and solar systems with asteroid belts as large as an entire solar system, such the the matter for planetary formation was available but no planets formed despite the existence of a proto-planetary disc. It is an especially interesting question whether lithium had any role to play in the planetary formation or the lack thereof in either of these cases.

However, lithium-planetary system correlation relies on our very sketchy knowledge of exoplanet systems at present. All of this knowledge is strongly skewed toward large planets that tug their stars around. Astronomers have been able to figure out the planetary system around Alpha Centauri because it is close enough to detect the smaller wiggles that would betray smaller planets, but even here we don’t have any information about what surrounds the star other than a few planets. Stars without any large planets at all might have many smaller planets, or they might have a solar system sized asteroid belt. There are probably also a few stars in which all the precursor materials managed to get into the star with very little left over for planets or asteroids.

Perhaps it could be said that lithium deficiency correlates with the absence of large planets, because we have no idea what may be surrounding stars with no detectable large planets — not until we have a very large telescope in orbit or on the moon. This too suggests interesting questions. How might the formation of large planets be correlated with lithium deficiency in a star? Also, it has been theorized that large planets clear debris out of a solar system, thereby making it possible for smallish, rocky planets to exist in a more stable planetary environment, and a more stable planetary environment likely correlates with the emergence of life and eventually industrial-technological civilization. Thus lithium-planetary system correlation could extend all the way to being a predictor of industrial-technological civilizations.

It might be fruitful to compare the lithium spectra from double (and triple) star systems with known systems including hot Jupiter exoplanets (some of which are just short of being companion stars) and stars that show no evidence of large planet formation. Also, it is worth considering whether double stars or hot Jupiters play a role in the formation of other planets, e.g., such a large gravitational mass might upset the proto planetary disc just enough that the disc congeals into (large) planets, whereas the absence of such a gravitational “trigger” might result in greater uniformity in the proto-planetary disc and therefore its failure to congeal into discrete planets.

Such inquiries are now only in their infancy, and we can both expect and look forward to a flowering of knowledge in the fields of planetary science and space science as the technology to image distant stars and planetary systems rapidly improves, and as access to earth orbit becomes routine, allowing for a robust multiplicity of telescopes in earth orbit outside the atmosphere.

Not only will science on the whole be stimulated by this research, but, as I have often argued, it is the intrinsic nature of industrial-technological civilization to be spurred on by scientific innovations that result in new technologies, and new technologies are engineered into new industries that go on to create new scientific instruments that increase and improve scientific knowledge. Thus the cycle that defines and drives industrial-technological civilization escalates. This cycle is nowhere even close to being exhausted; as I have just pointed out above, instead of a handful of telescopes in orbit, the next decades may see hundreds if not thousands of telescopes in orbit, as there are now thousands of telescopes on the surface of the earth.

Civilization itself will be the beneficiary of these developments, as it continues its spiral of technological progress with its unexpected and unpredicted advantages for human life and commercial opportunity. There is also the sheer joy of better understanding the world in which we live. All of these factors will continue to fuel the growth and diversification of civilization in the future, thus at least partially mitigating against the existential risk of permanent stagnation.

The transplanetary perspective resulting from the extrapolation and generalization of earth sciences into planetary science and space sciences is to be welcomed for these far-reaching benefits both practical and intellectual.

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Earth Science, Planetary Science, Space Science

Wednesday

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Earth and the moon in one frame as seen from the Galileo spacecraft 6.2 million kilometers away. (from Picture of Earth from Space by Fraser Cain)

It is ironic, though not particularly paradoxical, that the earth sciences as we known them today only came into being as the result of the emergence of space science, and space science was a consequence of the advent of the Space Age. We had to leave the Earth and travel into space in order to see the Earth for what it is. Why was this the case, and what do I mean by this?

It has often been commented that we had to go into space in order to discover the earth, which is to say, to understand that the earth is a blue oasis in the blackness of space. The early images of the space program had a profound effect on human self-understanding. Photographs (as much or more than any theory) provided the theoretical context that allowed us to have a unified perspective on the Earth as part of a system of worlds in space. Once we saw the Earth for what it was, What Carl Sagan called a “pale blue dot” in the blackness of space, drove home a new perspective on the human condition that could not be forgotten once it had been glimpsed.

To learn that our sun was a star among stars, and that the stars were suns in their own right, that the Earth is a planet among planets, and perhaps other planets are other Earths, has been a long epistemic struggle for humanity. That the Milky Way is a galaxy among galaxies, a point that has been particularly driven home by recent observational cosmology as with the Hubble Ultra-Deep Field (UDF) image (and now the Hubble eXtreme-Deep Field (XDF) image), is an idea that we still today struggle to comprehend. The planethood of the Earth, the stellarhood of the sun, the galaxyhood of the Milky Way are all exercises in contextualizing our place in the universe, and therefore an exercise in Copernicanism.

But I am getting ahead of myself. I wanted to discuss the earth sciences, and to try to understand what they are and how they have become what they are. What are the Earth sciences? The Biology Online website has this brief and concise definition of the earth sciences:

The Earth Sciences, investigating the way our planet works and the mechanisms of nature that drive it.

The geology.com website has a more detailed definition of the earth sciences that already hints at their relation to the space sciences:

Earth Science is the study of the Earth and its neighbors in space… Many different sciences are used to learn about the earth, however, the four basic areas of Earth science study are: geology, meteorology, oceanography and astronomy.

For a more detailed overview of the earth sciences, the Earth Science Literacy Initiative (ESLI), funded by the National Science Foundation, has formulated nine “big ideas” of earth science that it has published in its pamphlet Earth Science Literacy Principles. Here are the nine big ideas taken from their pamphlet:

1. Earth scientists use repeatable observations and testable ideas to understand and explain our planet.

2. Earth is 4.6 billion years old.

3. Earth is a complex system of interacting rock, water, air, and life.

4. Earth is continuously changing.

5. Earth is the water planet.

6. Life evolves on a dynamic Earth and continuously modifies Earth.

7. Humans depend on Earth for resources.

8. Natural hazards pose risks to humans.

9. Humans significantly alter the Earth.

Each of these “big ideas” is further elaborated in subheadings that frequently bring out the planethood of the Earth. For example, section 2.2 reads:

Our Solar System formed from a vast cloud of gas and dust 4.6 billion years ago. Some of this gas and dust was the remains of the supernova explosion of a previous star; our bodies are therefore made of “stardust.” This age of 4.6 billion years is well established from the decay rates of radioactive elements found in meteorites and rocks from the Moon.

Intuitively, we would say that the earth sciences are those sciences that study the Earth and its natural processes, but the rapid expansion of scientific knowledge has made us realize that the Earth is not a closed system that can be studied in isolation. The Earth is part of a system — the solar system, and beyond that a galactic system, etc. — and must be studied as part of this system. But we didn’t always know this, and this comprehensive conception of earth science is still in the process of formulation.

The realization that the processes of the Earth and the sciences that study these processes must ultimately be placed in a cosmological context means that contemporary earth science is now, like astrobiology, which seeks to place biology in a cosmological context, a fully Copernican science, though not perhaps quite as explicitly as in the case of astrobiology. The very idea of Earth science as it is understood today, like planetary science and space science, is essentially Copernican; Copernicanism is now the telos of all the sciences. Copernican civilization needs Copernican sciences. As I said in my presentation to this year’s 100YSS symposium, the scope of an industrial-technological civilization corresponds to the scope of the science that enables this civilization.

What this means is that the sciences that generations of Earth-bound scientists have labored to create in order to describe the planet upon which they have lived, which was the only planet that they could know prior to the advent of space science, are all planetary sciences in embryo — all potentially Copernican sciences that can be extended beyond the Earth that was their inspiration and origin. Before space science, all science was geocentric and therefore essentially Ptolemaic. Space science changed that, and now all the sciences are gradually becoming Copernican.

In the case of earth science, this is a powerful scientific model because the earth sciences have been, by definition, geocentric. That even geocentric sciences can become Copernican is a powerful lesson and provides a model for other sciences to follow. I have often quoted Foucault as saying that “A real science recognizes and accepts its own history without feeling attacked.” I think it can be honestly said that the geosciences recognize and accept their history as geocentric sciences and this in no way inhibits their ability to transcend their geocentric origins and become Copernican sciences no longer exclusively tied to the Earth. I find this rather hopeful for the future of science.

Another way to conceptualize earth science is to think of the earth sciences as those sciences that have come to recognize the planethood of the Earth. This places the Earth in its planetary context among other planets of our solar system, and it also places these planets (as well as the growing roster of exoplanets) in the context of planetary history that we have learned first-hand from the Earth.

To a certain extent, earth science and planetary science (or planetology) are convertible: each is increasingly formulated and refined in reference to the other. What is planetary science? Here is the Wikipedia definition of planetary science:

Planetary science (rarely planetology) is the scientific study of planets (including Earth), moons, and planetary systems, in particular those of the Solar System and the processes that form them. It studies objects ranging in size from micrometeoroids to gas giants, aiming to determine their composition, dynamics, formation, interrelations and history. It is a strongly interdisciplinary field, originally growing from astronomy and earth science, but which now incorporates many disciplines, including planetary astronomy, planetary geology (together with geochemistry and geophysics), atmospheric science, oceanography, hydrology, theoretical planetary science, glaciology, and the study of extrasolar planets.[1] Allied disciplines include space physics, when concerned with the effects of the Sun on the bodies of the Solar System, and astrobiology.

The Division for Planetary Sciences of the American Astronomical Society doesn’t give us the convenience of a definition for planetary science, but in its offerings on A Planet Orbiting Two Suns, A Thousand New Planets, Buried Mars Carbonates, The Lunar Core, Propeller Moons of Saturn, A Six-Planet System, Carbon Dioxide Gullies on Mars, and many others, give us concrete examples of planetary science which examples may, in certain ways, be more helpful than an explicit definition.

Jupiter’s moon Europa may have liquid water beneath its icy surface, kept warm inside by the enormous gravitational forces of Jupiter. Planet science is endlessly fascinating, and we learn new things about planetology almost every day.

The “aims and scope” of the journal Earth and Planetary Science Letters also give something of a sense of what planetary science is:

Earth and Planetary Science Letters (EPSL) is the journal for researchers, policymakers and practitioners from the broad Earth and planetary sciences community. It publishes concise, highly cited articles (“Letters”) focusing on physical, chemical and mechanical processes as well as general properties of the Earth and planets — from their deep interiors to their atmospheres. Extensive data sets are included as electronic supplements and contribute to the short publication times. EPSL also includes a Frontiers section, featuring high-profile synthesis articles by leading experts to bring cutting-edge topics to the broader community.

A recent (2006) controversy over the status of Pluto as a planet led to an attempt by The International Astronomical Union (IAU) to formulate a more precise definition of what a planet is. The definition upon which they settled demoted Pluto from being a planet to being a dwarf planet. While this decision does not have complete unanimity, it is gaining ground in the literature. Here is the IAU of planets, dwarf planets, and small solar system bodies:

(1) A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.
(2) A “dwarf planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
(3) All other objects, except satellites, orbiting the Sun shall be referred to collectively as “Small Solar System Bodies.”

With this greater precision of definition than had previously been the case in regard to planets, we could easily define planetary science as the study of celestial bodies that (a) are in orbit around the Sun, (b) have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (nearly round) shape, and (c) have cleared the neighbourhood around their orbits. Of course, this ultimately won’t do, because a comprehensive planetary science will want to study all three classes of celestial bodies detailed above, and will especially want to study the mechanisms of planet formation, dwarf planet formation, and small object formation for the light that each shines on the other. Like the Earth, that is part of a larger system, all the planets are also part of a larger system, and how they relate to that system will have much to teach us about solar system formation.

This more comprehensive perspective brings us to the space sciences. What is space science? The Wikipedia entry on space sciences characterizes them in this way:

The term space science may mean:

●The study of issues specifically related to space travel and space exploration, including space medicine.

●Science performed in outer space (see space research).

●The study of everything in outer space; this is sometimes called astronomy, but more recently astronomy can also be regarded as a division of broader space science, which has grown to include other related fields.

It is interesting that this definition of space science does not mention cosmology, which is more and more coming to assume the role of the master category of the sciences, since it is ultimately cosmology that is the context for everything else, but we could easily modify that last of the above three stipulations to read “cosmology” in place of “astronomy.” As the definition notes, the space sciences have grown to include other related fields, and in the future it may well be that the space sciences become the most comprehensive scientific category, providing the conceptual infrastructure in which all other scientific enterprises must be contextualized.

Since the Earth is a planet, and planets are to be found in space, one might readily assume that the Earth sciences, planetary sciences, and space sciences might be arranged in a nested hierarchy as follows:

Conceptually this is correct, but genetically, i.e., in terms of historical descent, it is obvious that the sciences that we have created to study our home planet are the sciences that, when generalized and applied beyond the surface of the Earth, are the sciences that become planetary science and space science.

Before space science and planetary science, there were of course the familiar sciences of geology (later geomorphology), atmospheric science or meteorology (later climatology), oceanography, paleontology, and so forth, but it was only when the emergence of space science and planetary science placed these terrestrial sciences into a cosmological context that we came to see that our sciences that study the planet that we call our home together constitute the Earth sciences in contrast to, and really in the context of, space science and planetary science. Great strides have been made in this direction, but further work remains to be done.

Geologic timescales for Earth and Mars with rocks plotted at the age of their emplacement. The age of soil samples analyzed by landed missions to Mars are too uncertain to plot on Fig. 4, and since no rocks were analyzed at the Viking 1 landing site in Chryse Planitia, that site is not shown. Martian geologic timescale of Hartmann and Neukum (2001), with subdivisions indicating the early, middle, and late Noachian, early and late Hesperian, and early, middle, and late Amazonian.

We know that the Earth and its solar system is about 4.6 billion years old, and most recent estimates for the age of the known universe put it at about 13.7 billion years. This means that the Earth has been around for almost exactly a third of age of the entire universe, which is not an inconsiderable length of time. Our sun and its solar system stands in relation to other stars of a similar age, and these stars and solar systems with significant traces of heavier elements stand in certain relationships to earlier populations of stars. The whole history of the universe is present in the rocks of the Earth, and we have to keep this in mind in the expanding knowledge base of the earth sciences.

While geological time scales are essentially geocentric, it would be possible to formulate an astrogeography and an astrogeographical time scale, extrapolating earth science to planetary science and thence to space science, that not only placed Earth’s geological history into cosmological context but also placed all planetary bodies and planetary systems and their geology in a cosmological context. For such an undertaking the generations of stars and planetary formation would be of central concern, and we could expect to see patterns across stars and solar systems of the same generations, and across planets within a given solar system.

This work has already begun, as can be seen in the above table laying out the geological histories of the Earth, the Moon, and Mars in parallel. Since one of the major theories for the formation of the Moon is that most of its substance was ripped out of the Earth by an enormous collision, the geological histories of the Earth and the Moon may ultimately be shown to coincide.

Stars and planets formed from the same dust and debris clouds filled with the remnants of the nucleosynthesis of earlier poulations of stars. This is now familiar to everyone. Galaxies, in turn, formed from stars, and thus also reflect a generational index reflecting a galaxy’s position in the natural history of the universe.

Since we now also believe that all or almost all spiral galaxies (and perhaps also other non-spiral or irregular galaxies) have a supermassive black hole at their centers, I have lately come of think of entire galaxies as the vast “solar systems” of supermassive black holes. In other words, a supermassive black hole is to a galaxy as a star is to a solar system. As planetary systems formed around newly born stars, galaxies formed around newly born black holes (if their gravity was sufficiently strong to form such a system). This way of thinking about galaxies introduces another parallelism between the microcosm of the solar system and the macrocosm of the universe at large, the structure of which is defined by galaxies, clusters of galaxies, and super clusters.

All of this falls within a single natural history of which we are a part.

Our history and the history of the universe are one and the same.

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The Taxonomy of the Sciences

Thursday

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There is passage in Foucault, in the preface to the English language of The Order of Things, after the more famous passage about the “Chinese dictionary” in Borges, in which he discusses a pathological failure of taxonomy. The theme of Foucault’s book, restated compellingly in this preface, is taxonomy — taxonomy in its most general (and therefore its most philosophical) signification. Taxonomy is a problem.

It appears that certain aphasiacs, when shown various differently coloured skeins of wool on a table top, are consistently unable to arrange them into any coherent pattern; as though that simple rectangle were unable to serve in their case as a homogeneous and neutral space in which things could be placed so as to display at the same time the continuous order of their identities or differences as well as the semantic field of their denomination. Within this simple space in which things are normally arranged and given names, the aphasiac will create a multiplicity of tiny, fragmented regions in which nameless resemblances agglutinate things into unconnected islets; in one corner, they will place the lightest-coloured skeins, in another the red ones, somewhere else those that are softest in texture, in yet another place the longest, or those that have a tinge of purple or those that have been wound up into a ball. But no sooner have they been adumbrated than all these groupings dissolve again, for the field of identity that sustains them, however limited it may be, is still too wide not to be unstable; and so the sick mind continues to infinity, creating groups then dispersing them again, heaping up diverse similarities, destroying those that seem clearest, splitting up things that are identical, superimposing different criteria, frenziedly beginning all over again, becoming more and more disturbed, and teetering finally on the brink of anxiety.

THE ORDER OF THINGS: An Archaeology of the Human Sciences, MICHEL FOUCAULT, A translation of Les Mots et les choses, VINTAGE BOOKS, A Division of Random House, Inc., New York, Preface

Taxonomy is the intersection of words and things — and just this was the original title of Foucault’s book, i.e., words and things — and Foucault brilliantly illustrates both the possibilities and problems inherent in taxonomy. Foucault had an enduring concern for taxonomy, and, as is well known, named his chair at the Collège de France the “History of Systems of Thought” — as though he were seeking a master taxonomy of human knowledge.

Foucault found madness and mental illness in the inability of a test subject to systematically arrange skeins of wool, since each attempted scheme of classification breaks down when it overlaps within another system of classification pursued simultaneously. One suspects that if the task placed before Foucault’s aphasiac were limited in certain ways — perhaps in the number of colors of wool, or the number of categories that could be employed — the task might become practical once a sufficient number of constraints come into play. But the infinite universe investigated by contemporary science is the very antithesis of constraint. There is always more to investigate, and as the sciences themselves grow and fission, begetting new sciences, the task of bringing order to the sciences themselves (rather than to the empirical phenomena that the sciences seek to order) becomes progressively more difficult.

The taxonomy of the sciences is more problematic that usually recognized. Consider these possible categories of science, not all of which are current today:

● natural sciences It is still somewhat common to speak of the “natural sciences,” with our intuitive understanding of what is “natural” as sufficient to classify a given study as an investigation into “nature.” What, then, is not a natural science? At one time there was a strong distinction made between the natural sciences and the formal sciences (q.v.)

● formal sciences The phrase “formal sciences” is rarely used today, though it is still a useful idea, comprising at least mathematics and logic and (for those who know what it is) formal mereology. Today the formal sciences might also include computer science and information science, though I haven’t myself ever heard anyone refer to these sciences as formal sciences. Since the mathematization of the natural sciences beginning with the scientific revolution, the natural sciences have come more and more to approximate formal sciences, to the point that mathematical physics has, at times, only a tenuous relationship to experiments in physics, while it has a much more robust relationship with mathematics.

● moral sciences Philosopher J. R. Lucas has written of the moral sciences, “The University of Cambridge used to have a Faculty of Moral Sciences. It was originally set up in contrast to the Faculty of Natural Sciences, and was concerned with the mores of men rather than the phenomena of nature. But the humane disciplines were hived off to become separate subjects, and when the faculty was finally renamed the Faculty of Philosophy, philosophy was indeed the only subject studied.”

● earth sciences The earth sciences may be understood to be a subdivision of the natural sciences, and may be strongly distinguished from the space sciences, but the distinction between the earth sciences and the space sciences, as well as these two sciences themselves, is quite recent, dating to the advent of the Space Age in the middle of the twentieth century. While the idea behind the earth sciences is ancient, their explicit recognition as a special division within the sciences is recent. I suspect that the fact of seeing the earth from space, made possible by the technology of the space age, contributed greatly to understanding the earth as a unified object of investigation.

● space sciences The space sciences can be defined in contradistinction to the earth sciences, as though science had a need to recapitulate the distinction between the sublunary and the superlunary of Ptolemaic cosmology; however, I don’t think that this was the actual genesis of the idea of a category of space sciences. The emergence of the “Space Age” and its associated specialty technologies, and the sciences that produced these technologies, is the likely source, but the question becomes whether a haphazardly introduced concept roughly corresponding to a practical division of scientific labor constitutes a useful theoretical category.

● social sciences The social sciences would obviously include sociology and cultural anthropology, but would it include biological anthropology? History? Political science? Economics? The social sciences often come under assault for their methodology, which seems to be much less intrinsically quantitative than that of the natural sciences, but are not social communities as “natural” as biologically defined communities?

● human sciences In German there is a term — Geisteswissenschaften — that could be translated as the “spiritual sciences,” and which roughly corresponds to the traditional humanities, but it is not entirely clear whether the human sciences coincide perfectly either with Geisteswissenschaften or the humanities. Foucault’s The Order of Things, quoted above, is subtitled, “An Archaeology of the Human Sciences,” and the human sciences that Foucault examines in particular include philology and economics, inter alia.

● life sciences I assume that “life sciences” was formulated as a collective term for biological sciences, which would include studies like biogeography, which might also be called an instance of the earth sciences, or the natural sciences. But the life sciences would also include all of medicine, which gives us a taxonomy of the medical sciences, though it does not give us a clear demarcation between the life sciences and the natural sciences. Does medicine include all of psychiatry, or ought psychiatric inquiries to be thought of as belonging to the social sciences?

● historical sciences I have written about the historical sciences in several posts, since S. J. Gould often made the point that that historical sciences have a distinctive methodology. In Historical Sciences I argued that there is a sense in which all sciences can be considered historical sciences. Indeed, one of the distinctive aspects of the scientific revolution has been to force human beings to stop assuming the eternity and permanence of the world and to see the world and everything in it as having a natural history. If everything has a natural history, then all investigations are historical investigations and all sciences are historical sciences — but if this is true, then Gould’s claim that the historical sciences have a unique methodology collapses.

There are also, of course, informal distinctions such as that between the “hard” sciences and the “soft” sciences, which is sometimes taken to be the distinction between mathematicized sciences and non-mathematicized sciences, and so may correspond to the rough distinction between the natural sciences and the social sciences, except the that the social sciences are now dominated by statistical methods and can no longer be thought of a non-mathematicized. This leads to problems of classification such as whether economics, for example, is a natural science or a social science.

For each of the science categories above we could attempt either an extensional or an intensional definition, i.e., we could give a list of particular sciences that fall under the category in question, or we could attempt to define the meaning of the term, and the meaning would then govern what sciences are so identified. An extensional definition of the earth sciences might involve a list including geomorphology, biogeography, geology, oceanography, hydrology, climatology, and so forth. An intentional definition of the earth sciences might be something like, “those sciences that have as their object of study the planet earth, its subsystems, and its inhabitants.”

Today we employ the sciences to bring order to our world, but how do we bring order to the sciences? Ordering our scientific knowledge is problematic. It is complicated. It involves unanticipated difficulties that appear when we try to make any taxonomy for the sciences systematic. Each of the scientific categories above (as well as others that I did not include — my list makes no pretension of completeness) implies a principled distinction between the kind of sciences identified by the category and all other sciences, even if the principle by which the distinction is to be made is not entirely clear.

The implicit distinction between the earth sciences and the space sciences has a certain intuitive plausibility, and it is useful to a certain extent, though recently I have tried to point out in Eo-, Exo-, Astro- the importance of astrobiology as unifying terrestrial biology and exobiology in a truly Copernican framework. While the attempted task of a taxonomy of the sciences is important, the nature of the task itself suggests a certain compartmentalization, and too much thinking in terms of compartmentalization can distract us from seeing the larger synthesis. Concepts based on categorization that separates the sciences will be intrinsically different from extended conceptions that emerge from unification. An exclusive concern for the earth sciences, then, might have the subtle affect of reinforcing geocentric, Ptolemaic assumptions, though if we pause for a moment it will be obvious that the earth is a planet, and that the planetary sciences ought to include the earth, and the the planetary sciences might be construed as belonging to the space sciences.

The anxiety experience by Foucault’s aphasiac is likely to be experienced by anyone attempting a systematic taxonomy of the sciences, as here, any mind, whether sick or healthy, might continue to extrapolate distinctions to infinity and still not arrive at a satisfactory method for taking the measure of the sciences in way that contributes both to the clarity of the individual sciences and an understanding of how the various special sciences relate to each other.

On the one hand, perfect rigor of thought would seem to imply that all possible distinctions must be observed and respected, except that not all distinction can be made at the same time because some cut across each other, are mutually exclusive, order the world differently, and subdivide other categories and hierarchies in incompatible schemes. To use a Leibnizean term, not all distinctions are compossible.

To invoke Leibniz in this context is to suggest a Leibnizean approach to the resolution of the difficulty: a Leibnizean conception of conceptual rigor would appeal to the greatest number of distinctions that are compossible and yield a coherent body of knowledge.

A thorough-going taxonomic study of human bodies of knowledge would reveal a great many possible taxonomies, some with overlapping distinctions, but it is likely that there is an optimal arrangement of distinctions that would allow the greatest possible number of distinctions to be employed simultaneously while retaining the unity of knowledge. This would be a system of compossible taxonomy, which might have to reject a few distinctions but which makes use of the greater number of distinctions that are mutually possible within the framework of methodological naturalism as this defines the scientific enterprise.

There are not merely academic considerations. The place of science within industrial-technological civilization means that our conception of science is integral with our conception of civilization; thus to make a systematic taxonomy of the sciences is to make a systematic taxonomy of a civilization that is based upon science. Such conception categories extrapolated from science to civilization will have consequences for human self-understanding and human interaction, which latter does not always take the form of “cultural exchanges” (in the saccharine terminology if international relations). Industrial-technological civilization is in coevolution with industrial-technological warfare, so that a taxonomy of science is also a taxonomy of scientific warfare. Our conception of science will ultimately influence how we kill each other, and how we seek peace in order to stop killing each other.

One of the most distinctive forms of propaganda and social engineering of our time is the creation from whole cloth of artificial and fraudulent sciences. Since science is the condition of legitimacy in industrial-technological civilization, social movements seeking legitimacy seek scientific justification for their moral positions, but the more that science is seen as a means to an end, where the end is stipulated in advance, then science as a process must be compromised because any science that does not tend to the desired socio-political end will be subject to socio-political disapproval or dismissal. While there is a limit to this, the limits are more tolerant than we might suppose: large, complex societies with large and diverse economies can sustain non-survival behavior for a significant period of time — perhaps enough time to conceal the failure of the model employed until it is too late to save the society that has become a victim of its own illusion.

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Eo-, Exo-, Astro-

Monday

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This post has been superseded by Eo-, Eso-, Exo-, Astro-, which both corrects and extends what I wrote below.

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The Philosophical Significance of Astrobiology as a

Cosmological Extrapolation of Terrestrial Biology

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In yesterdays’ Commensurable Perspectives I finished with this observation:

Ecology is the master world-narrative that unifies the sub-narratives employed by individual species in virtue of their perceptual and cognitive architecture. Ultimately, astrobiology would constitute the universal narrative that would unify the ecological narratives of distinct worlds.

The naturalistic narrative has the power to unify even across species and across worlds. This power may not be particularly evident at present, but in the long term future of our species (if our species does in fact have a long term future) this power will prove to be crucial.

If indeed astrobiology is the universal narrative of life, that gives astrobiology a privileged position among the sciences. That is a tall order. But what is astrobiology? At one time I had heard both the terms “exobiology” and “astrobiology” and I was not quite clear about the exact difference between the two, or how each was defined. Thereby hangs a tale. The distinction between the two is in fact a very interesting story, and it is a story to which an entire book has been devoted, The Living Universe: NASA and the Development of Astrobiology, by Steven J. Dick and James E. Strick.

I urge the reader to get this book and peruse it for yourself for the detailed version of the emergence of astrobiology as a scientific discipline. I will give only the bare bones of that story here, which will be only enough to grasp the crucial concepts involved. And our interest is in the concepts, not the personalities.

Joshua Lederberg before he had formulated the distinction between eobiology and exobiology.

Exobiology is the older term, introduced by Joshua Lederberg (first used in a public lecture in 1960), and contrasted by him to eobiology. Exobiology has some currency in the public mind, but I didn’t know about eobiology until I read about the history of the discipline. However, the contrast between the two terms is conceptually important. Exobiology is concerned with biology off the surface of the earth, while eobiology is biology on the surface of the earth. (cf. p. 29) In other words, all biological science prior to human spaceflight was eobiology, even if we didn’t know that it was eobiology. Another way to formulate this distinction is to say that eobiology is the biology of the terrestrial biosphere, while exobiology is the biology of everything else.

In the book The Living Universe: NASA and the Development of Astrobiology the authors give a lot of background on the internal politics and budgeting of NASA and how this affected the emergence of astrobiology. It is an interesting story, but I will not go into it here, as our interest at present is exclusively with the conceptual infrastructure of the discipline. Suffice it to say that in 1996 the first attempts were made to define astrobiology (cf. p. 202), and within a couple of years there was a virtual Astrobiology Institute.

The NASA astrobiology website characterizes astrobiology as follows:

“Astrobiology is the study of the origin, evolution, distribution, and future of life in the universe. This multidisciplinary field encompasses the search for habitable environments in our Solar System and habitable planets outside our Solar System, the search for evidence of prebiotic chemistry and life on Mars and other bodies in our Solar System, laboratory and field research into the origins and early evolution of life on Earth, and studies of the potential for life to adapt to challenges on Earth and in space.”

The NASA strategic plan of 1996 gives this definition of astrobiology:

“The study of the living universe. This field provides a scientific foundation for a multidisciplinary study of (1) the origin and distribution of life in the universe, (2) an understanding of the role of gravity in living systems, and (3) the study of the Earth’s atmospheres and ecosystems.”

The important lesson to take away from this is that astrobiology is the more comprehensive concept, and that in fact we can consider astrobiology the union of eobiology and exobiology. This sounds simple enough (and it is), but it is important to understand the conceptual leap that has been taken here.

From the perspective of astrobiology, earth sciences are only fragments of far larger and more comprehensive sciences. Just as all biology was once eobiology, the same observation can be made in regard to the other earth sciences, and the same tripartite conceptual distinction can be brought to the other earth sciences. We can formulate eogeology and exogeology unified in astrogeology; we can formulate eohydrology and exohydrology unified in astrohydrology; we can formulate eovulcanology and exovulcanology unified in astrovulcanology; we can formulate eoclimatology and exoclimatology unified in astroclimatology. All of these are cosmological extrapolations of earth sciences. One suspects that, in the future, the prefixes will be dropped and we will return to climatology simpliciter, e.g., but while the conceptual revolution is underway it is important to retain the prefixes as a reminder that science is no longer defined by the boundaries of the earth.

I assert that this is a conceptual leap of the first importance because what we have with astrobiology is the formulation of the first truly Copernican science; astrobiology includes eobiology but it is not exhausted by eobiology; it is supplemented by exobiology. The earth, for obvious reasons, remains important to us, but it no longer dictates the center of our science. All mature sciences will eventually need to take this Copernican turn and dethrone the earth from the center of its concern.

We can take a further step beyond this conceptual formulation of Copernican sciences by observing that traditional earth sciences began as local enterprises, and it has only been in recent decades that truly global sciences have emerged. These global sciences have culminated in objects of scientific study that take the world entire as their object. Thus biology has converged upon study of the biosphere; hydrology has converged on study of the hydrosphere; glaciology has culminated in the study of the cryosphere. Copernican sciences based on the model of astrobiology can go one better than this, transcending earth-defined “-spheres” in favor of more comprehensive concepts.

When I spoke last year on “The Moral Imperative of Human Spaceflight” at the NASA/DARPA 100 Year Starship Study symposium it was my intention to spend some time on the emergence of Copernican sciences, but I didn’t have enough time to elaborate. I cut most of that material out and still was rushed. The point that I wanted to make there was that the concepts of the biosphere, the lithosphere, the geosphere, hydrosphere, cryosphere, atmosphere, anthrosphere, sociosphere, noösphere, and technosphere are essentially Ptolemaic concepts. (If the proceedings of the symposium are published, and if my paper is included, this contains my first sketch of Copernican sciences as transcending these earth-defined “-spheres.”) The Copernican Revolution entails the formulation of Copernican concepts to supersede Ptolemaic concepts, and this work is as yet unfinished. In some spheres of human thought, it has scarcely begun.

One way to transcend our Ptolemaic concepts and to replace them with Copernican concepts, and thus to extend the ongoing shift to a truly Copernican perspective, is to substitute for the earth-defined “-spheres” a conception of the object of the sciences not dependent upon the earth, and this can be done by defining, respectfully, biospace (in place of the biosphere), lithospace, geospace, hydrospace, cryospace, atmospace, anthrospace, sociospace, noöspace, and technospace. In so far as we can facilitate the emergence of Copernican sciences, we can contribute to the ongoing Copernican Revolution, which will someday culminate in a Copernican civilization (if we do not first destroy ourselves).

We can pass beyond the earth sciences and the natural sciences and similarly extend our conceptions of a the social and political sciences. Although concepts from the social sciences are not usually expressed in geocentric terms — except for the above-mentioned anthrosphere, sociosphere, noösphere, and technosphere (which are not employed very often) — our social and political thought is usually even more tied to planetary prejudices than the concepts of the natural sciences. Thus we can extend our conception of politics by distinguishing between eopolitics and exopolitics, both of which are subsumed under astropolitics. Similarly, we can formulate eoeconomics and exoeconomics, subsumed by astroeconomics, eostrategy and exostrategy, subsumed by astrostrategy, and so forth.

As a final note, it is ironic that the breakthrough to a Copernican science should occur first with biology, because biology was among the latest of the sciences to actually attain a scientific status. Prior to Darwin, biological theories were essentially theological theories with but a few exceptions. Darwin put biology on a firm biological footing and created the discipline in its modern scientific form. Thus biology was among the last of the sciences to attain a modern scientific form, though it was the first to attain to a Copernican form.

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This post has been superseded by Eo-, Eso-, Exo-, Astro-.
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