31 December 2016
Four Species of Big History
While in several posts I have attempted to analyze the positivistic outlook of much contemporary science, which views philosophy like a vampire views garlic and holy water, we all know that the absence of an explicit and acknowledged metaphysic virtually guarantees an implicit and hidden metaphysic. There is a considerable philosophical literature on the metaphysical presuppositions of science; I have written about this also, and in Reduction, Emergence, Supervenience I distinguished between four phases of scientific metaphysics: the eliminativist, the reductionist, the emergentist, and the supervenientist (although when I wrote that post I hadn’t yet fully distinguished eliminativism as a scientific metaphysic).
In so far as Big History constitutes the culmination of scientific historiography, Big History is history informed by the metaphysical presuppositions of natural science. If, then, we take my four divisions of scientific metaphysics as the possible forms that these metaphysical presuppositions can take, we have the four metaphysical forms that Big History can take: eliminativist big history, reductionist big history, emergentist big history, and supervenientist big history. I will consider each of these possibilities in turn.
Already in Reduction, Emergence, Supervenience, in a section titled “Reduction, emergence, and supervenience as philosophies of history,” I began an explicit outline of scientific historiography as founded on these scientific metaphysics:
● Eliminativist Historiography Human history is illusory and should be eliminated as a category of thought; everything history states that is true can be better and exhaustively expressed in a scientific language that makes no use of folk historiography. Therefore we can substitute scientific explanations for historical explanation without change in truth or loss of truth. It would be sufficient to provide a total description of the physics of the past without any overlay of human meanings or values.
● Reductionist Historiography Human history is nothing but natural history, or the history of the world as related by science (which is not necessarily the same thing as natural history). If human meanings and values seem to play a constitutive role in history (or even human consciousness, in the form of making conscious choices), this is merely illusory, an error the follows from human limitations.
● Emergentist Historiography Human history is a whole that emerges from natural history that possesses unique properties as a whole that are not attributable to natural historical processes.
● Supervenient Historiography Human history supervenes on natural history, or the history of the world as related by science. In other words, there can be no change in human history without there being a subvening change in natural history. The A-properties of history supervene upon the B-properties of scientifically delineated history.
The above is a modified version of what I wrote in my earlier post.
Eliminativist Big History
What would be eliminated in a eliminativist big history? Presumably the concepts and categories of folk historiography, as those positivist enthusiasts of eliminativism generally focused on eliminating “folk” concepts (cf. Folk Concepts and Scientific Progress). What are the folk concepts of historiography? Folk concepts of historiography would probably include all or most of the factors highlighted by personalism in history, i.e., concepts of individual human agency, which also might be identified with folk psychology: motivation, intention, purpose, meaning, value, and so on. A scientific historiography would also presumably seek to eliminate all the folk concepts still present in the special sciences made use of by scientific historiography.
How would this play out in Big History? Big History pursued as a form of metaphysical reductionism would resemble a spare and stripped-down scientific historiography more than any other metaphysical formulation under consideration here. The only novel element would be treating the whole history of the universe in these terms of scientific historiography, instead of restricting the scope of such a scientific historiographical enterprise.
Indeed, Otto Neurath, one of the movers and shakers of the Vienna Circle, already foresaw such a reductionist Big History, which he called “Cosmic History”:
“…we may look at all sciences as dovetailed to such a degree that we may regard them as parts of one science which deals with stars, Milky Ways, earth, plants, animals, human beings, forests, natural regions, tribes, and nations — in short, a comprehensive cosmic history would be the result of such an agglomeration… Cosmic history would, as far as we are using a Universal Jargon throughout all branches of research, contain the same statements as our unified science. The language of our Encyclopedia may, therefore, be regarded as a typical language of history. There is no conflict between physicalism and this program of cosmic history.”
Otto Neurath, Foundations of the Social Sciences, Chicago and London: The University of Chicago Press, 1970 (originally published 1944), p. 9
For Neurath to assert that, “There is no conflict between physicalism and this program of cosmic history,” is to say that history can be subsumed under the physicalism of the Encyclopedia of Unified Science in which the above-quoted monograph appeared, and this means that history could be reduced to protocol sentences of physics. While most historians would, I think, not find this to be congenial, it is remarkable that Neurath conceived this cosmic history as part of the program of unified science, and that it resembles so closely the ambition of Big History.
Reductionist Big History
Reductionism usually takes the form of reducing some higher-level, more comprehensive (or more complex) state-of-affairs to a lower-level, less comprehensive (or less complex) state of affairs; without denying the reality of the higher-level state-of-affairs, but also denying the latter metaphysical primacy. A good example of this is Hilbert’s philosophy of mathematics, which sought to preserve Cantor’s set theory and transfinite numbers, but only by making a distinction between real and ideal mathematics, consigning Cantor to the latter and reserving the former for quasi-constructivist, proto-finitist mathematics. Hilbert “reduced” ideal mathematics to real mathematics, but without insisting upon the elimination of ideal mathematics, and in a similar way reductionist historiography would “reduce” human history to natural history (or to time itself), without insisting upon the elimination of human history.
Like the idealist doctrine of degrees of being, in reductionism there are degrees of reality. Without denying the reality of higher-level, more comprehensive states-of-affairs, these are said to be reducible to, or, “nothing but” the lower-level, less comprehensive states-of-affairs. If we understand history to be a higher-level, more comprehensive conception than time, the reductionist big history would take the form of asserting that history is reducible to time, or that history is nothing but time. But the reductionist does not take the additional step taken by the eliminativist, so that the reductionist does not assert either that history is unreal or time unreal, or that these are meaningless. Both are real, but each enjoys a different degree of reality. This interpretation of reductionism as a doctrine of degrees of reality could be given further exposition, but it opens up so many problems (and so many opportunities) that I will not consider it further at present.
It must be admitted that there are strong reductionist strains in scientific historiography, and many of these are retained in the movement of the ideas of scientific historiography into Big History. If it is argued that some major historical development is entirely due to climate change, or geography, or cosmological circumstances like the fact that Earth had only one moon, and so on, we are here approximating a purely reductionist Big History. This kind of reductionism is antithetical to personalism in history, in which human actors loom large, but while the eliminativist Big Historian might simply do without any reference to human actors in history, the reductivist Big Historian would retain human actors, but would ascribe their actions to larger forces, be those forces fundamental physics, cosmology, geography, or something else.
Emergentist Big History
Emergentism, unlike eliminationism and reductionism, has a prominent and explicit place in Big History. Big Historians usually recognize eight thresholds of emergent complexity in the history of the universe — the big bang, stars, chemical elements, planets, life, human beings, argiculture, and modernity — at least, these are the thresholds made canonical by David Christian. There are alternative periodizations based on thresholds of emergent complexity, but most Big Historians recognize some sort of periodization of the history of the universe entire based on emergent complexity.
One of the similes employed by contemporary philosophers to explain the ambition of metaphysics is the idea of carving nature at the joints. This is precisely what Big Historians are trying to do in using emergent complexity as a basis for periodization. Historians have always employed periodizations; with Big History, these periodizations are now drawn not from human conventions, but from the actual history of nature itself, from the very structure of the universe, and thus are quantifiable and can be studied by science. Here scientific historiography is “cashed out” by making periodization subject to rigorous scientific research. It would be difficult to imagine a more perfect exemplification of a metaphysical synthesis of science and history.
While emergentism features prominently in Big History, the Big History version of emergent complexity has not yet been a focus of research by philosophers, and so it lacks the clarity and ambition to system that we would expect to find in a more philosophical account. In some accounts of Big History, emergentism is invoked rather than explained or exhibited, so there remains much work to be done. Big History employs emergentism, but it could not be said that Big History is as yet a thoroughly emergentist conception of history — we could apply the idea of emergence more systematically and exhaustively — nor could we say that the possibilities of emergentism in the philosophy of history have been even sketched out. I suspect that we will begin to see this in the coming decade.
Supervenientist Big History
I know of no explicit formulation of supervenientist Big History, but as a more subtle and sophisticated philosophical doctrine than its predecessors eliminationism, reductionism, and emergentism, it is not difficult to imagine that someone will, sooner rather than later, employ the metaphysical tools of supervenience to the analysis of history. Supervenience could be interpreted in a way consistent with reductionism or emergentism, so these iterations of the metaphysics of Big History could be considered precursors that eventually lead to a more sophisticated formulation in terms of supervenience. (It should, however, be pointed out that the formulation of emergentism in the first section above, “Human history is a whole that emerges from natural history that possesses unique properties as a whole that are not attributable to natural historical processes,” is not consistent with supervenience, while implies that there could be formulations of emergentist historiography inconsistent with supervenientist historiography.)
Because supervenience is a sophisticated metaphysical doctrine, there are many different formulations with subtle differences. Thus there could be many different forms of supervenientist Big History (as noted above, some compatible with emergence, and some not, and the same could be said of elimination and reduction), depending upon the variety of supervenience one employs in demonstrating that historical properties supervene on some base properties. But what do we take to be the base properties upon which historical properties supervene? Are these base properties temporal properties, or human properties, or physical properties of the universe? One of the reasons I have been emphasizing the relationship between time and history is because in my recent post A Metaphysical Disconnect I argued that the fact that the philosophy of time is not tightly-coupled with the philosophy of history points to a major disconnect. Seen in the might of supervenience, that might have historical properties supervene on properties of human societies rather than properties of time, there is here the suggestion of an argument in favor of the disconnect that I noted.
A supervenientist Big History rapidly becomes so bogged down in technical details that I will have to save an attempt at a brief exposition for a later time, as I do not yet have a grasp of this that would allow me to summarize the issues with any degree of accuracy. Nevertheless, I will not the possibility of a supervenientist Big History as a direction that research into the metaphysics of Big History could take in the near future.
The Future: Big History after Scientific Metaphysics
In the fullness of time, assuming our civilization does not falter and so continues in its development (i.e., assuming the failure condition), the contemporary paradigm of science will become so altered by revision and addition that it will no longer be recognizable as what we today think of as science. Science itself will be forced to expand and to change in order to encompass objects of knowledge not accessible by contemporary scientific methods (e.g., consciousness). This change will be both influenced by changes in our philosophical outlook, and will in turn influence the shaping of our philosophical outlook. As a consequence, the metaphysical presuppositions of science will evolve along with the evolution of scientific method. The quadripartite schema I have laid out above of eliminativist, reductionist, emergentist, and supervenientist scientific metaphysics will give way to other ways of conceptualizing the world.
Big History, as an expression of scientific historiography, and thus an expression of science and of scientific civilization, will change along with the changes in scientific method and metaphysical presuppositions of history. There will always be a division of history that takes as its remit the most comprehensive conception of history, and in this sense there will always be Big History, though eventually it will be Big History without the metaphysical presuppositions of science that now subtly inform scientific historiography.
Scientific metaphysics is the intellectual superstructure of scientific civilization. In the illustration below I suggest an overall tripartite distinction among pre-scientific metaphysics, scientific metaphysics (i.e., the metaphysics that facilitates science), and post-scientific metaphysics. There is almost certain further developments of scientific metaphysics to come, which will continue to illuminate the scientific civilization of which we are part. But at some point the accumulated differences will push us over a threshold beyond which the scientific paradigm no longer applies, and that post-scientific civilization will have to be illuminated by a post-scientific metaphysics.
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
18 December 2012
The slow percolation of metaphysical ideas into human experience
It took some two hundred years or more for Rousseau’s ideas to trickle down from philosophical speculation to popular consciousness and practical implementation. Much of what has its origins in Rousseau only came to fruition in the second half of the twentieth century as the environmental movement and the counter-culture movement. Some of Rousseau’s ideas found more immediate application: his book The Social Contract was an influence in revolutionary France and continues to have a profound influence on Western political thought. But most philosophical ideas only percolate through history over time, and come to have an indirect influence only after they have become so familiar that they are no longer thought of as philosophical ideas.
We expect that the philosophical ideas that will broadly affect the lives of individuals in mass society will be those political and ethical ideas such as we find in Rousseau’s political works, but even rarefied metaphysical concepts like reduction, emergence, and supervenience can, given the passage of time, become as commonplace as Rousseau’s incipient environmentalism has become the now through the pervasively-present environmental movement. It is worth recalling in this connection that the concept of zero was once advanced mathematics, and very difficult to conceive for peoples possessing only limited mathematical conceptual resources, while it is now taught in the earliest years of school and is easily mastered by young children. Philosophical ideas must often make a pilgrimage like that of the concept of zero: from an outlandish proposal to a universally accepted presupposition that lies at the foundation of all other thought.
It can, however, be difficult to recognize when subtle and complex metaphysical ideas have entered into the popular mind as these concepts ever-so-slowly filter into the exposition of the big ideas that shape civilization. The process can be so slow and gradual that, like evolutionary processes, they cannot be seen on a timescale that human beings can immediately perceive. Or, rather, a particular effort — a philosophical effort — must be made in order to perceive this development.
Some metaphysical ideas: reduction, emergence, supervenience
What is reduction? What is reductionism? What is emergence? What is emergentism? What is supervience? How are these ideas related?
Here is how The Blackwell Dictionary of Western Philosophy defines reduction:
“A position based on the assumption that apparently different kinds of entities or properties are identical and claiming that items of some types can be explained in terms of more fundamental types of entities or properties with which they are identical.”
“reductionism” in The Blackwell Dictionary of Western Philosophy, edited by NICHOLAS BUNNIN and JIYUAN YU
Here is a definition of emergence:
“Philosophy of science, philosophy of social science based on the assumption that a whole is more than the sum of all its parts, the doctrine of emergence holds that the whole has properties which cannot be explained in terms of the properties of its parts. Such a property is called an emergent property. The enormous complexity of the interactions among parts leads to the generation of a property of the whole that cannot be deduced from the properties of parts.”
“emergence” in The Blackwell Dictionary of Western Philosophy, edited by NICHOLAS BUNNIN and JIYUAN YU
And here is a (somewhat longer, and therefore less clear) definition of supervience from the same source:
“A term which can be traced to G. E. Moore , but which gained wider use through the work of R. M. Hare. Hare used it for the claim that moral or evaluative properties such as goodness must supervene upon natural properties such as intelligence, health, and kindness. If something has the moral property in virtue of having the natural property and if anything having the natural property would in virtue of having it also have the moral property, then the moral property supervenes upon the natural property. If two things are alike in all descriptive respects, the same evaluative properties must be applied to both of them. On this view, good is supervenient upon underlying natural properties, although it is not reducible to them. Davidson extended this notion to the philosophy of mind, and claims that mental properties are supervenient upon physical properties. If two things are alike in all physical properties, they can not differ in mental properties, but the mental can not be reduced to the physical. Supervenient physicalism offers an alternative to reductionist identity theory. Supervenience is an irreducible relation of dependence upon base properties by supervenient properties.”
“supervenience” in The Blackwell Dictionary of Western Philosophy, edited by NICHOLAS BUNNIN and JIYUAN YU
This last definition of supervenience is a little less clear than the others because supervenience is a more subtle idea than reduction or emergence, and the difficulty of the idea has led the author to express the idea in something less than full philosophical generality.
We can think of the sequence of ideas represented by reductionism, emergentism, and supervenience as the progressively more subtle and detailed reconciliation of philosophy with the discoveries of the physical sciences since the scientific revolution, and more especially since the advent of industrial-technological civilization, which latter has seen such a dramatic acceleration of the ability of science to explain the world.
Contemporary metaphysical ideas in relation to science
These three definitions don’t give a sense of the continuity of philosophical development that links the ideas of reduction, emergence, and supervenience together. The three ideas may appear not as stages in the development of a philosophical perspective informed by contemporary science, and, truth be told, they are not usually presented in this way, but this is how I see them. Before I say more about the interrelationship of the three, however, I’m going to give a sketch of the relation of Western philosophical thought to science.
Ancient philosophy began with the macroscopic features of human experience open to all; philosophical observation, scientific observation, and mathematical observation were all one and the same. Only religious “observation” (i.e., specifically religious experiences such as mystical trance and ecstatic possession) stood apart as giving a special insight into the nature of things that was not publicly open and available in the same way that the observations of ordinary experience are open to all. The common sense view of the world that is so central to ancient philosophy, even when it was decisively rejected by Plato (and then vigorously reasserted by Aristotle), was based on ordinary experience of this kind.
Since the time of classical antiquity new forms of observation, and new forms of systematizing observation, have emerged, and the most fundamental of these forms of observation and theorizing are known as science. Subsequent to the scientific revolution — which is an ongoing revolution because science gives us not a truth but a method — philosophy has been forced to transcend its origins in the manifest worldview of macroscopic observation and to integrate the discoveries of science that derive from more disciplined and systematic forms of observation. The principle of public accessibility is as central to science as it was to ancient common sense — perhaps we could even say that it is more central, if there were any such thing as one thing being “more” central than another — and any scientific observation or theory is not only open to the investigations of others, but it is assumed that any scientific result will immediately mean that others will seek to duplicate the result. However, the efforts to duplicate a result increase in difficulty as science increases in complexity, driven by earlier science. This limits the accessibility of advanced scientific results, and forces us to rely not on our own experience, but upon the painstaking work of others.
Philosophy today, then, is centered on the extended conceptions of “experience” and “observation” that science has opened up to us, and these extended senses of experience and observation go considerably beyond ordinary experience, and the prima facie intellectual intuitions available to beings like ourselves, whose minds evolved in a context in which perceptions mattered enormously while the constituents and overall structure of the cosmos mattered not at all. Thus we are faced with a profound philosophical struggle to attempt to arrive at novel intellectual intuitions that will guide us through the experiences and observations made possible by contemporary science. This fundamentally distinguishes the contemporary philosophical project from the philosophical project of classical antiquity, when Western philosophy originated.
The metaphysical interpretation of contemporary science
We can understand reductionism, emergentism, and supervenience as stages in the philosophical attempt to reconcile the results of scientific experience and observation with a comprehensive conception of the world of the kind of philosophy seeks to formulate. This philosophical vision of a comprehensive conception of the world may today be understood as the attempt to build a bridge between the results of contemporary science and the ordinary experiences that were once the exclusive concern of philosophy. Any truly comprehensive conception of the world would have to find some way to show that ordinary experience follows from the extraordinary observations of science, or vice versa. Reduction, emergence, and supervenience are three strategies for demonstrating such a relationship.
In fact, the sequence of development from reductionism through emergentism to supervenience neatly conforms to the Hegelian dialectic:
● The Reductionist Thesis Wholes are nothing but their constituent parts, to which they can be reduced by analysis.
● The Emergentist Antithesis Wholes possess unique properties not possessed by their parts, so that if a whole is reduced to its parts in analysis the emergent properties are not discoverable by the analysis.
● The Supervenience Synthesis Whole possess unique properties undiscoverable by analysis, but these properties supervene upon the properties of the parts.
Employing this Hegelian framework allows us to see the developmental connection between apparently opposed doctrines, and in fact this is how much thinking gets done: we perceive a flaw in our opponent’s position, so we point this out, then someone comes along later and shows how the two positions can be reconciled.
The intellectual development from reductionism through emergentism to supervenience roughly parallels the development from positivistic science through physicalism to contemporary naturalism. At each stage of this development, we find a refinement of the conception, and these refined conceptions will in turn be superseded by further innovations.
Reduction, emergence, and supervenience in sharper focus
Twentieth century science was (and, in some respects, remains) largely reductionist, and reductionism is familiar to everyone in many different forms. Whenever one finds, “nothing but,” as in, “x is nothing but y” — e.g., life is nothing but chemistry, man is nothing but a machine (after La Mettrie), mind is nothing but brain function, history is nothing but one damn thing after another — one finds reductionism. Reductionism should be familiar to us all, and probably most of us are equally aware of its dissatisfactions in the form of its notorious oversimplifications and the need to dismiss much that is essential to human experience as illusory or otherwise irrelevant.
Some contemporary philosophers dissatisfied not with reductionism, but feeling that reductionism is insufficiently radical in view of the results of science, have formulated “eliminativist” doctrines which maintain that ordinary experience does not reduce to scientific experience, but that ordinary experience is simply false and misleading, so it must be eliminated in favor of the scientific conceptions that have replaced intuitive conceptions. This is one source of the attempt to dismiss “folk psychology” and “folk physics” as relics of an earlier age that no longer have any meaning since they have been replaced by exact scientific concepts. I do not wish to make the claim that this is not a legitimate philosophical position, but it can never be the basis of a comprehensive conception of the world, because it makes not attempt to reconcile manifest experience with scientific results.
Reductionism is not in much favor now, but emergentism is slowly beginning to filter its way into the Western Weltanschauung. It started with gestalt psychology and then Buckminster Fuller’s use of the term “synergy” (which is now pervasively used in business-speak), and now emergentism in an explicit form is appearing in Big History, which is essentially a scientific Weltanschauung for a coming naturalistic age.
Even though Newton said “I make no hypotheses” (“hypotheses non fingo”), he nevertheless postulated gravitation as a universal force, and made no attempt to explain what gravitation is, only how it worked. In this Newtonian method we can see the origins both of instrumentalism, which foreswears any insight into the actual nature of the world, and emergentism, that posits wholes and properties of wholes, delineating how these wholes and their properties are distinct from parts of wholes and properties of parts, but not attempting to provide a mechanism that explains this distinction.
The idea of supervenience is a little more subtle than that of reduction or emergence, and, as a consequence of its subtlety, it will probably take proportionately longer for the concepts of supervenience to trickle down from philosophical theories into popular consciousness and practical implementation — but there is no reason to suppose that the moment of popular supervenience will never come. Precisely because supervenience is more subtle and sophisticated than the blunt instrument of reductionism and potentially has greater explanatory power than the positing of emergentism, the idea has a great future.
Supervenience offers one additional step beyond emergentism, a step that suggests, while not fully delineating, the mechanisms that give rise to emergent properties, but does so without the oversimplifications and ontological losses of reductionism. This may be the future of a more sophisticated future iteration of Big History in which emergentist themes are treated in terms of supervenience. That is but one possibility among countless others.
Reduction, emergence, and supervenience as philosophies of history
The absence of institutions and therefore the absence of procedural rationality informing all aspects of life means that the human condition under nomadic hunter-gatherer conditions is the least intellectualized iteration of the human condition. Ideas mattered little for our paleolithic ancestors. The introduction of institutions in agrarian civilizations forces a certain degree of the rationalization of life, and it was this degree of the rationalization of human social life that saw the emergence of philosophy (Jaspers’ Axial Age).
The introduction of specifically scientific institutions (both science itself, and the institution of industrial-technological civilization driven by science) saw an increase in several orders of magnitude of the rationalization of the human condition. Ideas matter much more now, even if we systematically fail to understand the role that ideas play in our lives. The metaphysical nature of civilization, in which life is shaped as much by ideas as by the necessities of life, means that with the introduction of civilized institutions, and the gradual maturation of these institutions, that the relationship between manifest experience and its manifest intuitions on the one hand, and the increasingly complex experiences and concepts of science are in more urgent need for unification in a single conceptual framework.
Is it possible to understand human history in metaphysical terms? The emerging scientific historiography of big history clearly suggests reductist, emergentist, and supervenience accounts of human history in relation to the scientific historiography that has so dramatically expanded our historical perspective beyond that of human testimony. The literary and humanistic tradition of historiography had its beginnings in ancient Greece almost simultaneously with the beginnings of philosophy, and both appealed to the same manifest experience of human beings as the only available paradigm for the foundation of knowledge.
If we formulate the distinction as that between between natural history in its most general signification (or scientific historiography, if you like) and human history, that is to say, history invested with human meanings and values, we can easily formulate a reductionist account of the relationship between natural history and human history, an emergentist account of the relationship between natural history and human history, and an account in terms of supervenience of the relationship between natural history and human history:
● Reductionist Historiography Human history is nothing but natural history. If human meanings and values seem to play a constitutive role in history (or even human consciousness, in the form of making conscious choices), this is merely illusory. If we wanted a stronger formulation of the same, we could frame an “eliminativist historiograpy.” (I leave this as an exercise to the reader.)
● Emergentist Historiography Human history is a whole that emerges from natural history that possesses unique properties as a whole that are not attributable to natural historical processes.
● Supervenient Historiography Human history supervenes on natural history. In other words, there can be no change in human history without there being a subvening change in natural history.
The reader can easily write the book comparing these three paradigms of metaphysical historiography with a minimum of effort and research. I think I’ve outlined enough of the relevant concepts to get you started.
The prospects for reduction, emergence, and supervenience
It seems obvious that supervenience is not an end point of philosophical development, but that it points toward further developments that will supersede supervenience as emergentism superseded reductionism and supervenience has superseded emergentism. Recently in The Emerging School of Techno-Philosophy I wrote that there has never been a more exciting time than the present to be a philosopher. Part of what makes our time so philosophically exciting is the question of what further scientific discoveries will require philosophical interpretation and what form of interpretation will follow after supervenience.
. . . . .
. . . . .
. . . . .