A Note on the Great Filter

29 October 2012


Are we ourselves, as the sole hominid species, the Great Filter?

Parochialism, ironically, knows no bounds. Our habit of blinkering ourselves — what visionary poet William Blake called “mind-forged manacles” — is nearly universal. Sometimes even the most sophisticated minds miss the simple things that are staring them in the face. Usually, I think this is a function of the absence of a theoretical context that would make it possible to understand the simple truth staring us in the face.

I have elsewhere written that one of the things that makes Marx a truly visionary thinker is that he saw the industrial revolution for what it was — a revolution — even while many who lived through this profound series of events where unaware that they were living through a revolution. So even if one’s theoretical context is almost completely wrong, or seriously flawed, the mere fact of having the more comprehensive perspective bequeathed by a theoretical understanding of contemporary events can be enough to make it possible for one to see the forest for the trees.

Darwin wrote somewhere (I can’t recall where as I write this, but will add the reference later when I run across it) that from his conversations with biologists prior to publishing The Origin of Species he knew how few were willing to thing in terms of the mutability of species, but once he had made his theory public it was rapidly adopted as a research program by biologists, and Darwin suggested that countless facts familiar to biologists but hitherto not systematically incorporated into theory suddenly found a framework in which they could be expressed. Obviously, these are my words rather than Darwin’s, and when I can find the actual quote I will include it here, but I think I have remembered the gist of the passage to which I refer.

It would be comical, if it were not so pathetic, that one of the first responses to Darwin’s systematic exposition of evolution was for people to look around for “transitional” evolutionary forms, and, strange to say, they didn’t find any. This failure to find transitional forms was interpreted as a problem for evolution, and expeditions were mounted in order to search for the so-called “missing link.”

The idea that the present consists entirely of life forms having attained a completed and perfected form, and that all previous natural history culminates in these finished forms of the present, therefore placing all transitional forms in the past, is a relic of teleological and equilibrium thinking. Once we dispense the unnecessary and mistaken idea that the present is the aim of the past and exemplifies a kind of equilibrium in the history of life that can henceforth be iterated to infinity, it becomes immediately obvious that every life form is a transitional form, including ourselves.

A few radical thinkers understood this. Nietzsche, for example, understood this all-too-clearly, and wrote that, “Man is a rope stretched between the beasts and the Superman — a rope over an abyss. A dangerous crossing, a dangerous wayfaring, a dangerous looking-back, a dangerous trembling and halting. What is great in man is that he is a bridge and not a goal..” But assertions as bold as that of Nietzsche were rare. Darwin himself didn’t even mention human evolution in The Origin of Species (though he later came back to human origins in The Descent of Man): Darwin first offered a modest formulation of a radical theory.

So what has all this in regard to Marx and Darwin to do with the great filter, mentioned in the title of this post? I have written many posts about the Fermi paradox recently without ever mentioning the great filter, which is an important part of the way that the Fermi paradox is formulated today. If we ask, if the universe is supposedly teaming with alien life, and possibly also with alien civilizations, why we haven’t met any of them, we have to draw that conclusion that, among all the contingencies that must hold in order for an industrial-technological civilization to arise within our cosmos, at least one of these contingencies has tripped up all previous advanced civilizations, or else they would be here already (and we would probably be their slaves).

The contingency that has prevented any other advanced civilization in the cosmos from beating us to the punch is called the great filter. Many who write on the Fermi paradox, then, ask whether the great filter is in our past or in our future. If it is in our past, we have good reason to hope that our civilization can be an ongoing concern. If it is in our future, we have a very real reason to be concerned, since if no other advanced civilization has made it through the great filter in their development, it would seem unlikely that we would prove the exception to that rule. So a neat way to divide the optimists and the pessimists in regard to the future of human civilization is whether someone places the great filter in the past (optimists) or in the future (pessimists).

I would like to suggest that the great filter is neither in our past or in our future. The great filter is now; we ourselves are the great filter.

Human beings are the only species (on the only biosphere known to us) known to have created industrial-technological civilization. This is our special claim to intelligence. But before us there were numerous precursor species, and many hominid species that have since gone extinct. Many of these hominids (who cannot all be called human “ancestors” since many of them were dead ends on the evolutionary tree) were tool users, and it is for this reason that I noted in Civilization and the Technium that the technium is older than civilization (and more widely distributed than civilization). But now we are only only remaining hominid species on the planet. So in the past, we can already see a filter that has narrowed down the human experience to a single sentient and intelligent species.

Writers on the technological singularity and on the post-human and even post-biological future have speculated on a wide variety of possible scenarios in which post-human beings, industrial-technological civilization, and the technium will expand throughout the cosmos. If these events come to past, the narrowing of the human experience to a single biological species will eventually be followed by a great blossoming of sentient and intelligent agents who may not be precisely human in the narrow sense, but in a wider sense will all be our descendants and our progeny. In this eventuality, the narrow bottleneck of humanity will expand exponentially from its present condition.

Looking at the present human condition from the perspective of multiple predecessor species and multiple future species, we see that the history of sentient and intelligent life on earth has narrowed in the present to a single hominid species. The natural history of intelligence on the Earth has all its eggs in one basket. Our existence as the sole sentient and intelligent species means that we are the great filter.

If we survive ourselves, we will have a right to be optimistic about the future of intelligent life in the universe — but not until then. Not until we have been superseded, not until the human era has ended, ought we to be optimistic.

Man is a narrow strand stretched between pre-human diversity and post-human diversity.

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Grand Strategy Annex

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A medieval illustration of the four humours: melancholic, choleric, phlegmatic, and sanguine (clockwise from upper left).

What is a definitive formulation?

Recently on my other blog I discussed the philosophical pursuit of definitive formulations. What is a definite formulation? The reader will, I am sure, immediately see that giving a concise and accurate idea of what constitutes a definitive formulation would itself require a definitive formulation of a definitive formulation.

I don’t yet have a definitive formulation of what constitutes a definitive formulation. I could simply say that it is a formulation of a concept that could serve as a definition, but this wouldn’t be very helpful. Here is how I characterized it in my other post:

“…a handful of short, clear, concise, and intuitively accessible sentences…”


“…to put this in clear and simple terms, if I have a definitive formulation, that means if you stopped me on the street and asked me to explain myself while standing on one foot, I could do it. Lacking definitive formulations, the attempted explanation would go on a little too long to be comfortable (or safely balanced) on one foot.”

Lacking a definitive formulation of an idea that is central to our thought means that we can only say what Augustine said of time in his Confessions:

What then is time? If no one asks me, I know: if I wish to explain it to one that asketh, I know not: yet I say boldly that I know, that if nothing passed away, time past were not; and if nothing were coming, a time to come were not; and if nothing were, time present were not. (11.14.17)

quid est ergo tempus? si nemo ex me quaerat, scio; si quaerenti explicare velim, nescio. fidenter tamen dico scire me quod, si nihil praeteriret, non esset praeteritum tempus, et si nihil adveniret, non esset futurum tempus, et si nihil esset, non esset praesens tempus.

In some cases, I think that we can move beyond this Augustinian limit to definition, and it is when we hit upon a definitive formulation that we are able to do this.

It seems appropriate that I should give a concrete example of something that I would identify as a definitive formulation, and since I have recently hit upon a formulation that I rather like, I will try to use this to show what a definitive formulation is.

Call it what you will… temperament, personality, disposition… but people are not all the same.

What is temperament?

I have written several posts about temperament, including Temperamental Diversity, A Third Temperament, Intellectual Personalities and Temperament and Civilization. I don’t think that philosophy, science, or socio-political thought has yet done justice to the role that temperament plays in the world.

But what is temperament? The seventh of ten definitions in the Oxford English Dictionary (which of the ten is the closest to the sense of “temperament” as I have been using the word) defines temperament as follows:

“Constitution or habit of mind, esp. as depending upon or connected with physical constitution; natural disposition”

The sixth of the OED definitions defines temperament in terms of the four humours recognized in medieval medical theory and practice:

“In mediæval physiology: The combination of the four cardinal humours (see humour n. 2b) of the body, by the relative proportion of which the physical and mental constitution were held to be determined; known spec. as animal temperament; also, The bodily habit attributed to this, as sanguine temperament, choleric temperament, phlegmatic temperament, or melancholic temperament (see the adjs.).”

In traditional philosophical parlance, a dictionary definition gives us a nominal definition, but as philosophers what we really want is a real definition. While the philosophical distinction between nominal and real definitions is ancient and widely familiar, and therefore probably ought to remain untouched, I think it is more intuitive to call these two kinds of definition formal definition and metaphysical definition. A formal definition situates the meaning of a term within a formal system, perhaps within the system of language, whereas a metaphysical definition situates the meaning of a term within the structure of the world. So I guess what I am saying here is that one function of a definitive formulation is to give a metaphysical definition — but to be able to do so without requiring the exposition of an entire metaphysical system. You can imagine why this might be difficult.

So, what would I offer as a definitive formulation of temperament, that (hopefully) goes beyond the formal (i.e., nominal) definition in the OED? I define temperament as follows:

Temperament is the intellectual expression of individual variability.

I hope that the reader doesn’t find this too anti-climactic. I’ll try to explain why I find this to be a fruitful formulation.

Ludwig Wittgenstein, former Russellian, later anti-Cantorian

The charm of an idea

A definitive formulation, as I understand it, has an aphoristic quality: it is brief, concise, sententious, and pregnant with meaning. It also has a certain indefinable “appeal” that, like most forms of appealingness, is compelling to some even while it leaves others cold.

Wittgenstein formulated this appeal by calling it the “charm” that some proofs in mathematics and the foundations of mathematics possess. The later Wittgenstein was concerned to criticize the whole Cantorian conception of set theory and transfinite numbers, and much of Wittgenstein’s later philosophical of mathematics has this purpose implicitly as the center of the exposition. (In connection with this, I have previously mentioned Brouwer’s influence on Wittgenstein in Saying, Showing, Constructing, and more recently wrote more about Brouwer in One Hundred Years of Intuitionism and Formalism.)

Here’s what Wittgenstein said about mathematical “charm” in his lectures of 1939:

“The proof has a certain charm if you like that kind of thing; but that is irrelevant. That fact that is has this charm is a very minor point and is not the reason why those calculations were made.–That is colossally important. The calculations have their use not in charm but in their practical consequences.”

“It is quite different if the main role or sole interest is this charm — if the whole interest is showing that a line does cut when it doesn’t, which sets the whole mind in a whirl, and gives the pleasant feeling of paradox. If you can show that there are numbers bigger than the infinite, your head whirls. This may be the chief reason this was invented.”

Ludwig Wittgenstein, Wittgenstein’s Lectures on the Foundations of Mathematics, Cambridge, 1939, edited by Cora Diamond, University of Chicago Press, 1989, p. 16

With this in mind, I am well aware that the “charm” that I find in my definitive formulation of temperament may well be lost on others. The fact that an idea that has a certain charm for one person has none for another is itself a function of temperament. Individuals of different temperaments will find an intellectual charm in different formulations.

Theoretical contextualization

Part of the charm that a formulation has (or fails to have) is the connections that it forges to familiar theories. A definitive formulation, among its other functions, contextualizes a less familiar or less precise concept in an established theory or theories, enabling a systematic exploration and exposition of the idea in relation to familiar and therefore more thoroughly explored theories. Well known theories provide clear parameters for an idea, which, when formerly known only in a vague and imprecise form, had no clear parameters.

In formulating temperament as the intellectual expression of individual variation I am contextualizing human temperament in evolutionary theory, and thereby suggesting an interpretation of temperament based in and drawing upon evolutionary psychology. Thus evolutionary theory provides the parameters for temperament understood as the intellectual expression of individual variability.

Individual variability is one of the drivers of natural selection. When distinct individuals have distinct properties, a selection event may favor (select for) some properties while disfavoring (select against) other properties. Usually we think of the properties of an organism as being structural features of an organism: one finch has a longer beak than another, or one ape is better at walking on two legs than another. These differences might disappear into the dustbin of natural history if no selection event comes along that favors one or the other. But if a selection event does occur, and it favors some structural attribute of an organism that varies among individuals, the favored individuals will go on to experience differential survival and reproduction.

While we usually think of selection in structural terms, a selection event can also select for behaviors. Organisms can adapt to their environment through behaviors just as certainly (and much more rapidly) than through structural changes in their bodies. Behavioral adaptation is no less significant in natural history than structural adaptation.

At very least with the emergence of human beings, and probably also with other species, both hominid precursors of homo sapiens and other large-brained mammals, mind emerged in natural history. With the emergence of mind, there emerged also a novel basis of selection. Some minds are constituted in one way, while other minds are constituted in other ways. In other words, the same individual variability we find in bodies and behaviors are also to be found in minds.

If a selection event occurs that should happen to favor (or disfavor) any one kind of mind over any other kind of mind, those possessing the favored minds will enjoy differential survival and reproduction. With individual variability of minds represented in a sentient population — individual temperaments that lead individuals to think in different ways, and value things in different ways, and deliberate over alternatives in different ways — there is the continual possibility of natural selection.

The more variety of minds that there are, the greater the number of alternatives amongst which a selection event can select, the greater the likelihood that some one temperament is more fitted to survive the particular conditions that obtain than other temperaments.

Thus to formulate temperament as the intellectual expression of individual variability is to place mind within natural history.

To place mind within nature is a metaphysical formulation.

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Grand Strategy Annex

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