Is encephalization the great filter?

Sunday

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Hominid encephalization reveals an exponential growth curve.

The idea of the great filter was formulated by Robin Hanson. In the exposition below Hanson also names a number of steps (acknowledged to be non-exhaustive) in the development of explosively expanding life:

“Consider our best-guess evolutionary path to an explosion which leads to visible colonization of most of the visible universe… The Great Silence implies that one or more of these steps are very improbable; there is a ‘Great Filter’ along the path between simple dead stuff and explosive life. The vast vast majority of stuff that starts along this path never makes it. In fact, so far nothing among the billion trillion stars in our whole past universe has made it all the way along this path. (There may of course be such explosions outside our past light cone [Wesson 90].)”

Robin Hanson, The Great Filter — Are We Almost Past It? 15 Sept. 1998

Discussion of the Great Filter has focused on singling out one factor and identifying this one factor as the Great Filter, although Hanson is explicit that, “one or more of these steps are very improbable.” In the event that several steps in the development of explosively expanding life rather than some one single step is unlikely, the Great Filter may consist of several elements. I think that this is an important qualification to make, but at present I will adopt the conventional presumption that one step in the development of advanced civilization is improbable (or especially improbable) and constitutes the Great Filter.

Graph of the encephalization quotient of several mammals.

What we know about the cosmos is consistent with it being rich in life, but poor in technologically advanced civilization. The more that we learn about exoplanetary systems (living, as we do, in the Golden Age of exoplanet discovery), the more our scientific understanding of the universe points toward a superfluity of habitable worlds (or, at least, potentially habitable worlds), even while no trace of intelligence has yet been seen or heard beyond Earth. Some of this may have to do with the amount of research funding that is channeled into astronomy and astrophysics in comparison to SETI research, which has received relatively little to date. This is about to change. A “Breakthrough Initiative” will be funneling a large amount of money into SETI — Breakthrough Listen — but there is no reason as yet to suppose that this effort will be any more successful than past efforts, though I would be quite pleased to be proved wrong.

Brain to body mass ratio is distinct from encephalization quotient (EQ).

The point that I made some time ago in SETI as a Process of Elimination still holds good: as our scientific instrumentation improves with each generation of technology, and our research methods become more sophisticated, we are able to exclude (and, correlatively, to include) an increasing number of possibilities and instances. In other words, progress in science comes about by falsifying certain hypotheses, as would be expected from a philosophy of science derived from the Popper-Lakatos axis. (It is often discussed in relation to SETI research that investigators are hesitant to publish negative results; perhaps if they better understood the crucial role of falsification in the methodology of the scientific research program that is SETI they would be more inspired to publish negative results.)

Comparative brain sizes of several mammals.

When, in the coming decades, we are able to obtain spectroscopic analyses of exoplanet atmospheres, our knowledge of what is going on on exoplanets — as opposed to merely knowing about their existence, location, size, orbital period, and so on, which is the kind of scientific knowledge we have only recently come into — will improve by an order of magnitude. At this point in time we will move from n_e in the Drake equation (number of planets, per solar system, with an environment suitable for life) to f_l (fraction of suitable planets on which life actually appears) and possibly also f_c (fraction of civilizations that develop a technology that releases detectable signs of their existence into space, from which we can infer f_i, fraction of life bearing planets on which intelligent life emerges) if exoplanet atmospheric signatures reveal signs of unambiguous industrial activity.

We do not know the prevalence of life in our galaxy, much less in the universe at large — i.e., whether or not we live in a biota-rich GHZ, or even CHZ (cosmic habitable zone) — but we may soon be able to estimate the presence of life in the cosmos as we can now estimate the number of planets in the cosmos. It is entirely possible that the universe is teaming with life, even advanced life that is as sophisticated as the life of the terrestrial biosphere. I have written elsewhere that we may live in a “universe of stromatolites” (cf. A Needle in the Cosmic Haystack), but we may also be living in the universe rich in the ecological equivalents of sharks, koalas, and penguins. With one exception: the emergence of the cognitive capacity that makes abstract intelligence possible as well as the civilization that is predicated upon it.

Do we live in a universe of stromatolites?

In an earlier post, A Note on the Great Filter, I suggested that we are the Great Filter. I would now like to refine this: if I were to identify a “Great Filter” (i.e., a single element constituting the Great Filter) somewhere between plentiful life and absent advanced technological civilizations, I would put my finger on hominid encephalization. It was the rapid encephalization of our hominid ancestors that made what we recognize as intelligence and civilization possible. While there are many other large brains in the animal kingdom — the whale brain and the elephant brain are significantly larger than the human brain — and other mammals have brains as convoluted as the human brain — meaning more of the neocortex, which makes up the outer layer of gray matter — the encephalization quotient of the human brain is significantly greater than any other animal.

Brain size in absolute terms may have to exceed a certain threshold before intelligence of the sort we seek to measure can be said to be present. Neurons are of a nearly constant size, so the minimal neuronal structure necessary to control bodily functions take up about the same space in a mouse and an elephant. Factors other than sheer brain size are relevant to brain function, as, for example, the portion of the brain made up by the cerebral cortex and the amount of convolutions (therefore outer surface area, and the cerebral cortex is outer layer). Hence the introduction of encephalization quotient: encephalization quotient is not simply a ratio of brain mass to body mass, but is also based on the expected brain size for a given body plan — this introduces an admitted interpretive element into EQ, but that does not vitiate the measure. When, in the distant future, we can compare EQs over many different species from many different biospheres, we can firm up these numbers. Someday this will be the work of astroneurology.

The ‘WOW!’ signal — fugitive signature of intelligence in an otherwise lonely universe? Perhaps astroneurology will someday study neural architecture across biospheres and arrive at a non-anthropocentric measure of intelligence that could account for something like the ‘WOW!’ signal.

The human brain (with its distinctive and even disproportionate EQ) has not changed since anatomical modernity — at least a hundred thousand years, and maybe as much as three hundred thousand years — and human thought has probably not greatly changed since the advent of cognitive modernity, perhaps seventy thousand years ago. We must continually remind ourselves that even the earliest anatomically modern human beings had a brain structurally indistinguishable from the human brain today. With the blindingly rapid gains of technological civilization over the past hundred years it is increasingly difficult to maintain a sense of connection to the past, not to mention the distant past. But when the human brain appeared in its modern form, it was unprecedented in its cognitive capacity — it was and still is an extreme outlier. There was nothing else like it on the planet, and from this brain followed control of fire, language, technology, art, and eventually civilization.

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Addendum on Marxist Eschatology

Saturday

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Yesterday in Marxist Eschatology I wrote:

Marx is the greatest exemplar of a perennial tradition of human thought that has been with us from the beginning and which will be with us as long as civilization and human life endures. This tradition wasn’t always called Marxism, and it won’t always be called Marxism, but the perennial tendency will remain. There will always be individuals who are attracted to the perennial idea that Marx represents, and as of the present time Marx remains the most powerful advocate of these ideas.

While on my other blog in Marx and Fukuyama I wrote:

With Marx, we can identify a “bend in the road” of history at which point Marx might be proved right or wrong. For some people — wrongly to my mind — this point was identified as the end of the Cold War. To my mind, it is the full industrialization of the world’s economy. Thus Marx’s thesis has the virtue of falsification.

This calls for a little clarification, since if interpreted uncharitably it might be found contradictory for Marxism to be a perennial idea and to be falsifiable, since what distinguishes a perennial idea is that it is not falsifiable — at least, not in a robust sense of falsification.

Karl Popper was the philosopher who formulated falsifiability as a criterion of scientificity (I’m not certain he was the first, be he has definitely been the most influential in advancing the idea of falsifiability, especially in contradistinction to the logical positivist emphasis on the verifiability criterion), and he discussed Marx at some length. Here’s nice summary from one of Popper’s later works:

“As I pointed out in my Open Society, one may regard Marx’s theory as refuted by events that occurred during the Russian Revolution. According to Marx the revolutionary changes start at the bottom, as it were: means of production change first, then social conditions of production, then political power, and ultimately ideological beliefs, which change last. But in the Russian Revolution the political power changed first, and then the ideology (Dictatorship plus Electrification) began to change the social conditions and the means of production from the top. The reinterpretation of Marx’s theory of revolution to evade this falsification immunized it against further attacks, transforming it into the vulgar-Marxist (or socioanalytic) theory which tells us that the ‘economic motive’ and the class struggle pervade social life.”

Karl Popper, Unended Quest, “Early Studies,” p. 45

I should point out that I agree with Popper’s arguments, and that Marxism construed in the narrow sense that Popper construed it was falsified by the events of the Russian Revolution. Lenin’s “weakest link of capitalism” theory was instrumental in the reinterpretation of Marxism that Popper mentioned. Beyond Lenin, Mao made even more radical changes by shifting the focus from the industrial proletariat to the agricultural peasant. It is a testament to the extent to which the twentieth century was not fully industrialized that it was Maoism rather than Marxism or Leninism that was the form of communism that reached the masses during the last century.

However, I think that there is a species of Marxism that lies between Popper’s narrowly conceived Marxism and the vulgar Marxism reinterpreted in the light of apparent falsification, and this is a Marxism that has been generalized beyond the historically specific conditions of the Russian Revolution, and even beyond the Cold War, which had almost nothing to do with democracy or communism and almost everything to do with national rivalry and the great game of power politics.

I have called a generalized Marxism a species of Marxism, and herein lies to clue to the distinction between Marxism and a perennial idea in the strict sense. Marxism (of one variety or another) is a species that falls under the genera of collectivist political thought. The latter — collectivist political thought — is a perennial idea, and lies beyond falsification. It is neither true nor false, but an ongoing influence, just like its implied contrary, which is individualist political thought. Individualism also lies beyond falsification, and is neither true nor false but remains an ongoing influence in human affairs.

Most forms of capitalism are individualist in orientation, though not all: oligarchical capitalist societies (like medieval Venice) had little to do with individualism. Thus a generalization of capitalism does not always lead to individualism. A generalization of capitalism, depending on its subtle differences in tone of market activity from one society to another, may lead to individualism, but it may also lead to a profoundly hierarchical crony capitalism, or to some other socio-economic formation.

Speaking generally for ideas, and not just communism and capitalism, and indeed not just political and economic ideas but all ideas, the generalization of an historically situated and therefore specific idea usually leads to a perennial idea if the generalization is sufficiently radical. The generalization of capitalism may or may not lead to individualism, but it will eventually lead to some perennial idea which lies beyond falsification, whether that idea is patriarchalism or something else. The generalization of Marxism, I think, leads more directly to a perennial form of collectivist thought, which at its greatest reach of generality is scarcely distinguishable from a vague sentimental connection to others.

The species of Marxism that I have posited — midway between Marxism narrowly conceived and Marxism generalized to the point of a vague feeling of cooperative common cause — is falsifiable, but it is not falsifiable by experiment. It is only falsifiable by history. It shares this property with other theses in the philosophy of history. This is one of the fundamental distinctions between the natural sciences and at least some of the historical sciences: theses in some of the historical sciences are falsifiable, but they are not falsifiable on demand. One can only wait and see if they are eventually falsified. With the passage of time the inductive evidence of an unfalsifiable thesis in the philosophy of history increases, but is never confirmed. Thus the philosophy of history, contrary to most expectations, is the most science-like of the branches of philosophy.

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Philosophy Teaching by Examples

Wednesday

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Thucydides

A quote quite frequently attributed to Thucydides is that history is philosophy teaching by example. The source of this quote does not seem to be Thucydides himself, though the idea could certainly said to be implicit throughout his work. The sophistication of Thucydides’ perspective suggests a philosophical subtlety, and Marcellinus tells us that Thucydides studied under Anaxagoras, as well as studying rhetoric with Antiphon. In any case, the source for this pseudo-Thucydidean quote seems to be Dionysius of Heraclea, Thus:

The contact with manners then is education; and this Thucydides appears to assert when he says history is philosophy learned from examples.

Dionysius of Heraclea, Ars Rhetorica (XI, 2, p. 212), (Tauchnitz edition)

Perhaps Thucydides said it, and tradition carried the saying to Dionysius of Heraclea, or perhaps Thucydides wrote it in a text now lost, but whatever the case the saying is clearly associated with Thucydides, even if we can’t trace it to an extant text.

In several posts I have touched on the possibility of historical falsification of ideas (cf. e.g., Confirmation and Disconfirmation in History), which also suggests the possibility of the historical verification of ideas, and the verification and falsification of ideas would constitute perfect instances of history teaching by examples.

In other posts I have also discussed counter-factual conditionals in relation to history, and it occurs to me today that counter-factual conditionals are simply the opposite perspective on history teaching philosophy by examples. With counter-factual conditionals we have events that did not in fact happen, but the fact that they did not occur but might have occurred has a lesson to teach us. With history teaching philosophy by example, we have events that did in fact happen, but which we understand might have been otherwise. Each illuminates the other because each is implied by the other. And in so far as each is implied by the other, the two are twin or parallel concepts.

I take it as a philosophical virtue to make parallel formulations explicit, and if we can find the appropriate linguistic formulation for the concepts we can demonstrate their parallelism all the better. For example, we could contrast counter-factual conditionals to factually-consonant conditionals, and then it becomes clear that all history is conditional. This was a theme that S. J. Gould emphasized on several occasions. I quoted him to this effect in The Immiserization Thesis.

In so far as any history, counter-factual or factually-consonant, accords with our ideas, whether validating them or falsifying them, is a matter of our ability to explicitly express these ideas in concrete terms. We can never specify all of the details that might emerge with the translation of ideas into facts and facts into ideas (something I discussed in Putting Ideas First), but we can certainly do better than we have in the past. And the closer we approximate the complexity of facts by filling out the complexity of our ideas beyond their usual abstract and schematic form, the closer we can get to speaking with any degree of precision of historical validation and falsification. And if I am correct that counter-factual conditionals and factually-consonant conditionals are parallel concepts, each shares in the difficulty of the other, even while an improvement in the formulation of the one suggests parallel improvements in the formulation of the other.

It cannot be too strongly emphasized that, even when an idea has been as rigorously disproved as it is possible for an idea to be disproved by history, even a disgraced and defeated idea is never put out of historical action entirely if it has some ongoing basis in human nature or in the perennial character of human affairs. We may know, for example, on an intellectual level that terrorizing civilians does not win wars, much less win hearts and minds, but when we find ourselves with our backs to the wall in an existential struggle, we may nevertheless choose to act upon tactics of mass terror — perhaps for revenge, perhaps to see the hated enemy suffer, perhaps out of sheer desperation or for lack of alternatives.

Similarly (again, a parallel formulation), even when an idea seems to be confirmed beyond any degree of rational doubt by actual historical events that appear to bear out the validity of that idea, we cannot allow ourselves to become smug about it, assuming its permanence. I am sure that almost every person who have lived in a stable society comes to believe in the permanency of the institutions of this society (which is what Sartre called the Spirit of Seriousness), only to be given a rude jolt when the seemingly permanent comes crashing down in a strategic shock or a revolution.

The validation and falsification of ideas by history are parallel concepts, just as countering or conforming to facts are parallel ideas. Extrapolating parallel concepts by applying advances with one idea to a parallel idea, mutatis mutandis, is one way to systematically extend the theoretical framework of our knowledge.

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