Nicholas Maxwell

Many scientists, if pushed, may be inclined to hazard the guess that the universe is comprehensible, even physically comprehensible. Almost all, however, would vehemently deny that science has already established that the universe is comprehensible. It is, nevertheless, just this that I claim to be the case. Once one gets the nature of science properly into perspective, it becomes clear that the comprehensibility of the universe is as secure an item of current scientific knowledge as anything theoretical in science can be, more secure, indeed, than the most firmly established fundamental theories of physics, such as quantum theory or Einstein's general theory of relativity

For over 30 years I have argued, in and out of print that, for both intellectual and humanitarian reasons, we urgently need a revolution in the aims and methods of academic inquiry. Instead of giving priority to the search for knowledge, academia needs to devote itself to seeking and promoting wisdom by rational means, wisdom being the capacity to realize what is of value in life, for oneself and others. Wisdom thus includes knowledge but much else besides. A basic task of academia would be to help humanity learn how to create a better world. Now I find the revolution is underway – entirely independent of my own efforts to promote it. During the last ten to twenty years, all sorts of changes have taken place in academia that amount to putting aspects of wisdom-inquiry into practice – even if in complete ignorance of my work. Perhaps the most significant steps are the creation of departments, institutions and research centres concerned with social policy, with problems of environmental degradation, climate change, poverty, injustice and war, and with such matters as medical ethics and community health. Nevertheless, the revolution is happening with agonizing slowness, in a dreadfully muddled and piecemeal way. It needs academics and non-academics to wake up to what is going on – or what needs to go on – to help give direction, coherence and a rationale to this nascent revolution from knowledge to wisdom.

Karl Popper is famous for having proposed that science advances by a process of conjecture and refutation. He is also famous for defending the open society against what he saw as its arch enemies – Plato and Marx. Popper’s contributions to thought are of profound importance, but they are not the last word on the subject. They need to be improved. My concern in this book is to spell out what is of greatest importance in Popper’s work, what its failings are, how it needs to be improved to overcome these failings, and what implications emerge as a result. The book consists of a collection of essays which dramatically develop Karl Popper’s views about natural and social science, and how we should go about trying to solve social problems. Criticism of Popper’s falsificationist philosophy of natural science leads to a conception of science that I call aim-oriented empiricism. This makes explicit metaphysical theses concerning the comprehensibility and knowability of the universe that are an implicit part of scientific knowledge – implicit in the way science excludes all theories that are not explanatory, even those that are more successful empirically than accepted theories. Aim-oriented empiricism has major implications, not just for the academic discipline of philosophy of science, but for science itself. Popper generalized his philosophy of science of falsificationism to arrive at a new conception of rationality – critical rationalism – the key methodological idea of Popper’s profound critical exploration of political and social issues in his The Open Society and Its Enemies, and The Poverty of Historicism. This path of Popper, from scientific method to rationality and social and political issues is followed here, but the starting point is aim-oriented empiricism rather than falsificationism. Aim-oriented empiricism is generalized to form a conception of rationality I call aim-oriented rationalism. This has far-reaching implications for political and social issues, for the nature of social inquiry and the humanities, and indeed for academic inquiry as a whole. The strategies for tackling social problems that arise from aim-oriented rationalism improve on Popper’s recommended strategies of piecemeal social engineering and critical rationalism, associated with Popper’s conception of the open society. This book thus sets out to develop Popper’s philosophy in new and fruitful directions. The theme of the book, in short, is to discover what can be learned from scientific progress about how to achieve social progress towards a better world.

In order to make progress towards a better world we need to learn how to do it. And for that we need institutions of learning rationally designed and devoted to helping us solve our global problems, make progress towards a better world. It is just this that we lack at present. Our universities pursue knowledge. They are neither designed nor devoted to helping humanity learn how to tackle global problems — problems of living — in more intelligent, humane and effective ways. That, this book argues, is the key disaster of our times, the crisis behind all the others: our failure to have developed our institutions of learning so that they are rationally organized to help us solve our problems of living — above all, our global problems. Having universities devoted almost exclusively to the pursuit of knowledge is a recipe for disaster. Scientific knowledge and technological know-how have unquestionably brought great benefits to humanity. But they have also made possible — even caused — our current global crises, above all the impending crisis of global warming. In this lucid and provocative book, Nicholas Maxwell argues convincingly that we need urgently to bring about a revolution in universities round the world so that their basic aim becomes wisdom, and not just knowledge.

My aim in this paper is to defend a version of the brain process theory, or identity thesis, which differs in one important respect from the theory put forward by J.J.C. Smart. I shall argue that although the sensations which a person experiences are, as a matter of contingent fact, brain processes, nonetheless there are facts about sensations which cannot be described or understood in terms of any physical theory. These 'mental' facts cannot be described by physics for the simple reason that physical descriptions are designed specifically to avoid mentioning such facts. Thus in giving a physical explanation of a sensation we necessarily describe and render intelligible that sensation only as a physical process, and not also as a sensation. If we are to describe and render intelligible a person's sensations, or inner experiences, as sensations, and not as physical processes occurring in that person's brain, then we must employ a kind of description that connot be derived from any set of physical statements

This paper considers objections to Popper's views on scientific method. It is argued that criticism of Popper's views, developed by Kuhn, Feyerabend, and Lakatos, are not too damaging, although they do require that Popper's views be modified somewhat. It is argued that a much more serious criticism is that Popper has failed to provide us with any reason for holding that the methodological rules he advocates give us a better hope of realizing the aims of science than any other set of rules. Consequently, Popper cannot adequately explain why we should value scientific theories more than other sorts of theories ; which in turn means that Popper fails to solve adequately his fundamental problem, namely the problem of demarcation. It is suggested that in order to get around this difficulty we need to take the search for explanations as a fundamental aim of science.

In this article I give a Darwinian account of how sentience, consciousness and language may have evolved. It is argued that sentience and consciousness emerge as brains control purposive actions in new ways. A key feature of this account is that Darwinian theory is interpreted so as to do justice to the purposive character of living things. According to this interpretation, as evolution proceeds, purposive actions play an increasingly important role in the mechanisms of evolution until, with evolution by cultural means, Darwinian evolution takes on a Lamarckian character. According to this view, as evolution proceeds, the mechanisms of Darwinian evolution themselves evolve.

An important part of the mind-brain problem arises because sentience and consciousness seem inherently resistant to scientific explanation and understanding. The solution to this dilemma is to recognize, first, that scientific explanation can only render comprehensible a selected aspect of what there is, and second, that there is a mode of explanation and understanding, the personalistic, quite different from, but just as viable as, scientific explanation. In order to understand the mental aspect of brain processes - that aspect we know about as a result of having relevant neurological processes occur in our own brain - we need to avail ourselves of personalistic explanation, irreducible to scientific explanation. The problem of explaining and understanding why experiential or mental aspects of brain processes or things should be correlated with certain physical processes, things or states of affairs is a non-problem because there is no kind of explanation possible in terms of which an explanation could be couched. A physical theory, amplified to include the experiential, might be predictive but would, necessarily, cease to be explanatory; and an amplified personalistic explanation could not succeed either. There is, in short, an explanation as to why there cannot be an explanation of correlations between physical and mental aspects of processes going on inside our heads

In order to create a good world, we need to learn how to do it - how to resolve our appalling problems and conflicts in more cooperative ways than at present. And in order to do this, we need traditions and institutions of learning rationally devoted to this end. When viewed from this standpoint, what we have at present - academic inquiry devoted to the pursuit of knowledge and technological know-how - is an intellectual and human disaster. We urgently need a new, more rigorous kind of inquiry that gives intellectual priority to the tasks of articulating our problems of living and proposing and critically assessing possible cooperative solutions. This new kind of inquiry would have as its basic aim to improve, not just knowledge, but also personal and global wisdom - wisdom being understood to be the capacity to realize what is of value in life. To develop this new kind of inquiry we will need to change almost every branch and aspect of the academic enterprise.

The crisis of our times is that we have science without wisdom. Modern science and technology lead to modern industry and agriculture which in turn lead to all the great benefits of the modern world and to the global crises we face, from population growth to climate change. The fault lies, not with science, but with science dissociated from a more fundamental concern with problems of living. We urgently need to bring about a revolution in academia so that the fundamental task becomes to help humanity learn how to tackle problems of living in increasingly cooperatively rational ways, so that we may gradually discover how to make progress towards a better, wiser world.

In this paper I argue for a kind of intellectual inquiry which has, as its basic aim, to help all of us to resolve rationally the most important problems that we encounter in our lives, problems that arise as we seek to discover and achieve that which is of value in life. Rational problem-solving involves articulating our problems, proposing and criticizing possible solutions. It also involves breaking problems up into subordinate problems, creating a tradition of specialized problem-solving - specialized scientific, academic inquiry, in other words. It is vital, however, that specialized academic problem-solving be subordinated to discussion of our more fundamental problems of living. At present specialized academic inquiry is dissociated from problems of living - the sin of specialism, which I criticize.

It is argued that purposive action of living things plays a crucial role in Darwinian evolution. As evolution proceeds, the mechanisms of evolution evolve as well, giving an increasingly important role to purposive action - to be understood in a sense which is compatible with physics (the atom of purposiveness being the thermostat). Nine versions of Darwinian theory are distinguished. The first denies that purposive action has any role in evolution at all; each successive version gives an inceasingly important role to purposive action. Of fundamental importance is The Principle of Non-Circularity: The theory must not presuppose what it seeks to explain.

Philosophy of science is seen by most as a meta-discipline – one that takes science as its subject matter, and seeks to acquire knowledge and understanding about science without in any way affecting, or contributing to, science itself. Karl Popper’s approach is very different. His first love is natural philosophy or, as he would put it, cosmology. This intermingles cosmology and the rest of natural science with epistemology, methodology and metaphysics. Paradoxically, however, one of his best known contributions, his proposed solution to the problem of demarcation, helps to maintain the gulf that separates science from metaphysics, thus fragmenting cosmology into falsifiable science on the one hand, untestable philosophy on the other. This has damaging repercussions for a number of issues Popper tackles, from the problem of induction to simplicity of theory and quantum theory. But his proposed solution to the demarcation problem is untenable. Metaphysical assumptions are an integral part of scientific knowledge, inherent in the persistent acceptance of unified theories against the evidence. Once this is appreciated, it becomes obvious that natural philosophy, a synthesis of science and philosophy, is both more rigorous and of greater intellectual value than the two dissociated components we have today. What Popper sought for could come to full fruition. Problems that Popper tackled, from the problem of induction, to the problem of unity of theory, problems of quantum theory, and problems concerning the scope and limits of physics, all receive more adequate resolution within the new, fully-fledged natural philosophy.

Science has been under attack ever since William Blake and Romantic movement. In our time, criticisms of modern science have led to Alan Sokal's spoof, and the so-called science wars. Both sides missed the point. Science deserves to be criticized for seriously misrepresenting its highly problematic aims, which have metaphysical, value and political assumptions associated with them. Instead of repressing these problematic aims, science ought rather to make them explicit, so that they can be critically assessed and, we may hope, improved.

Two great problems of learning confront humanity: (1) learning about the universe, and about ourselves as a part of the universe, and (2) learning how to make progress towards as good a world as possible. We solved the first problem when we created modern science in the 17th century, but we have not yet solved the second problem. This puts us in a situation of unprecedented danger. Modern science and technology enormously increase our power to act, but not our power to act wisely. All our current global crises have arisen as a result. What we need to do is learn from our solution to the first great problem of learning how to go about solving the second one. Properly implemented, this idea leads to a new kind of inquiry rationally devoted to helping humanity make progress towards as good a world as possible.

Imre Lakatos and Paul Feyerabend initially both accepted Popper's philosophy of science, but then reacted against it, and developed it in different directions. Lakatos sought to reconcile Kuhn and Popper by characterizing science as a process of competing research programmes, competing fragments of Kuhn's normal science. Feyerabend emphasized the need to develop rival theories to facilitate severe empirical testing of accepted theories, but then, as a result of a disastrous mistake, came to hold that theories that are incompatible with one another cannot be compared empirically. He ended up rejecting method in science. All four philosophers, Popper, Kuhn, Lakatos and Feyerabend missed the decisive defect in Popper's philosophy of science: persistent acceptance of unified theories only when endlessly many empirically more successful disunified rivals are available means that physics makes a big, highly problematic metaphysical assumption about the nature of the universe: it is such that some kind of underlying unity exists in nature. We need to adopt a new conception of science. In order to subject this implicit metaphysical conjecture to sustained critical assessment in an attempt to improve it, we need to see science as making a hierarchy of metaphysical assumptions about the knowability and comprehensibility of the universe, these assumptions becoming less substantial and more likely to be true as we ascend the hierarchy. Elements of Popper, Kuhn and Lakatos are to be found in this picture, but it also differs radically from all three. It more closely resembles Einstein's mature views about the nature of science.

After a sketch of the optimism and high aspirations of History and Philosophy of Science when I first joined the field in the mid 1960s, I go on to describe the disastrous impact of "the strong programme" and social constructivism in history and sociology of science. Despite Alan Sokal's brilliant spoof article, and the "science wars" that flared up partly as a result, the whole field of Science and Technology Studies is still adversely affected by social constructivist ideas. I then go on to spell out how in my view STS ought to develop. It is, to begin with, vitally important to recognize the profoundly problematic character of the aims of science. There are substantial, influential and highly problematic metaphysical, value and political assumptions built into these aims. Once this is appreciated, it becomes clear that we need a new kind of science which subjects problematic aims - problematic assumptions inherent in these aims - to sustained imaginative and critical scrutiny as an integral part of science itself. This needs to be done in an attempt to improve the aims and methods of science as science proceeds. The upshot is that science, STS, and the relationship between the two, are all transformed. STS becomes an integral part of science itself. And becomes a part of an urgently needed campaign to transform universities so that they become devoted to helping humanity create a wiser world.

Are special relativity and probabilism compatible? Dieks argues that they are. But the possible universe he specifies, designed to exemplify both probabilism and special relativity, either incorporates a universal "now" (and is thus incompatible with special relativity), or amounts to a many world universe (which I have discussed, and rejected as too ad hoc to be taken seriously), or fails to have any one definite overall Minkowskian-type space-time structure (and thus differs drastically from special relativity as ordinarily understood). Probabilism and special relativity appear to be incompatible after all. What is at issue is not whether "the flow of time" can be reconciled with special relativity, but rather whether explicitly probabilistic versions of quantum theory should be rejected because of incompatibility with special relativity.

We face grave global problems. One might think universities are doing all they can to help solve these problems. But universities, in successfully pursuing scientific knowledge and technological know-how in a way that is dissociated from a more fundamental concern with problems of living, have actually made possible the genesis of all our current global problems. Modern science and technology have led to modern industry and agriculture, modern medicine and hygiene, modern armaments, which in turn have led to habitat destruction, extinction of species, population growth, the lethal character of modern war, and the impending disasters of climate change. We urgently need to bring about a revolution in universities so that they put problems of living at the heart of the academic enterprise and take, as their basic task, to help humanity learn how to make progress towards as good a world as possible.

The basic task of the essay is to exhibit science as a rational enterprise. I argue that in order to do this we need to change quite fundamentally our whole conception of science. Today it is rather generally taken for granted that a precondition for science to be rational is that in science we do not make substantial assumptions about the world, or about the phenomena we are investigating, which are held permanently immune from empirical appraisal. According to this standard view, science is rational precisely because science does not make a priori metaphysical presuppositions about the world forever preserved from possible empirical refutation. It is of course accepted that an individual scientist, developing a new theory, may well be influenced by his own metaphysical presuppositions. In addition, it is acknowledged that a successful scientific theory, within the context of a particular research program, may be protected for a while from refutation, thus acquiring a kind of temporary metaphysical status, as long as the program continues to be empirically progressive. All such views unite, however, in maintaining that science cannot make permanent metaphysical presuppositions, held permanently immune from objective empirical evaluation. According to this standard view, the rationality of science arises, not from the way in which new theories are discovered, but rather from the way in which already formulated theories are appraised in the light of empirical considerations. And the fundamental problem of the rationality of science—the Humean problem of induction— concerns precisely the crucial issue of the rationality of accepting theories in the light of evidence. In this essay I argue that this widely accepted standard conception of science must be completely rejected if we are to see science as a rational enterprise. In order to assess the rationality of accepting a theory in the light of evidence it is essential to consider the ultimate aims of science. This is because adopting different aims for science will lead us, quite rationally, to accept different theories in the light of evidence. I argue that a basic aim of science is to explain. At the outset science simply presupposes, in a completely a priori fashion, that explanations can be found, that the world is ultimately intelligible or simple. In other words, science simply presupposes in an a priori way the metaphysical thesis that the world is intelligible, and then seeks to convert this presupposed metaphysical theory into a testable scientific theory. Scientific theories are only accepted insofar as they promise to help us realize this fundamental aim. At once a crucial problem arises. If scientific theories are only accepted insofar as they promise to lead us towards articulating a presupposed metaphysical theory, it is clearly essential that we can choose rationally, in an a priori way, between all the very different possible metaphysical theories that can be thought up, all the very different ways in which the universe might ultimately be intelligible. For holding different aims, accepting different metaphysical theories conceived of as blueprints for future scientific theories will, quite rationally, lead us to accept different scientific theories. Thus it is only if we can choose rationally between conflicting metaphysical blueprints for future scientific theories that we will be in a position to appraise rationally the acceptability of our present day scientific theories. We thus face the crucial problem: How can we choose rationally between conflicting possible aims for science, conflicting metaphysical blueprints for future scientific theories ? It is only if we can solve this fundamental problem concerning the aims of science that we can be in a position to appraise rationally the acceptability of existing scientific theories. There is a further point here. If we could choose rationally between rival aims, rival metaphysical blueprints for future scientific theories, then we would in effect have a rational method for the discovery of new scientific theories! Thus we reach the result: there is only a rational method for the appraisal of existing scientific theories if there is a rational method of discovery. I shall argue that the aim-oriented theory of scientific inquiry to be advocated here succeeds in exhibiting science as a rational enterprise in that it succeeds in providing a rational procedure for choosing between rival metaphysical blueprints: it thus provides a rational, if fallible, method of discovery, and a rational method for the appraisal of existing scientific theories—thus resolving the Humean problem. In Part I of the essay I argue that the orthodox conception of science fails to exhibit science as a rational enterprise because it fails to solve the Humean problem of induction. The presuppositional view advocated here does however succeed in resolving the Humean problem. In Part II of the essay I spell out the new aim-oriented theory of scientific method that becomes inevitable once we accept the basic presuppositional viewpoint. I argue that this new aim oriented conception of scientific method is essentially a rational method of scientific discovery, and that the theory has important implications for scientific practice.

The proper task of philosophy is to keep alive awareness of what our most fundamental, important, urgent problems are, what our best attempts are at solving them and, if possible, what needs to be done to improve these attempts. Unfortunately, academic philosophy fails disastrously even to conceive of the task in these terms. It makes no attempt to ensure that universities tackle global problems - global intellectually, and global in the sense of concerning the future of the earth and humanity. Universities do not give sustained attention to global problems (due to specialization and giving priority to the pursuit of knowledge) and as a result violate three of the four most elementary rules of rational problem solving conceivable. Judged from the standpoint of helping humanity tackle global problems, universities as at present constituted betray reason and, as a result, betray humanity. Bereft of institutions of learning rationally designed to help us make progress towards as good and wise a world as possible, not surprisingly we fail to learn how to do it. This is the key crisis of our times. And it is, at root, a failure of philosophy. It is the failure of philosophy to keep alive rational exploration of global problems in universities, and in the public domain - a failure that can be traced back to the origins of modern philosophy in the 17th century. We urgently need a revolution in philosophy so that academic philosophers take up their proper task of promoting rational exploration of our fundamental, global problems.

Neurosis can be interpreted as a methodological condition which any aim-pursuing entity can suffer from. If such an entity pursues a problematic aim B, represents to itself that it is pursuing a different aim C, and as a result fails to solve the problems associated with B which, if solved, would lead to the pursuit of aim A, then the entity may be said to be "rationalistically neurotic". Natural science is neurotic in this sense in so far as a basic aim of science is represented to be to improve knowledge of factual truth as such (aim C), when actually the aim of science is to improve knowledge of explanatory truth (aim B). Science does not suffer too much from this neurosis, but philosophy of science does. Much more serious is the rationalistic neurosis of the social sciences, and of academic inquiry more generally. Freeing social science and academic inquiry from neurosis would have far reaching, beneficial, intellectual, institutional and cultural consequences.

There is an urgent need to bring about a revolution in the overall aims and methods of academic inquiry, its whole character and structure, so that it takes up its proper task of promoting wisdom rather than just acquiring knowledge. We need to put right a philosophical blunder – a philosophical disaster one should perhaps say – that has overtaken academia, and is built into its structure. It is a blunder about what the overall aims and methods of academic inquiry ought to be. The responsibility to make clear what is wrong, and what needs to be done to put things right, lies above all with philosophers. This indeed, in my view, is the fundamental task for philosophy today: to shout out, loud and clear, that we urgently need to bring about an intellectual and institutional revolution in the aims and methods, the whole structure and character, of academic inquiry, so that it takes up its proper task of helping humanity learn how to create a wiser world. This, if philosophers really were serious about their subject and really did love wisdom, is what they would do. -/- .

"Understanding Scientific Progress constitutes a potentially enormous and revolutionary advancement in philosophy of science. It deserves to be read and studied by everyone with any interest in or connection with physics or the theory of science. Maxwell cites the work of Hume, Kant, J.S. Mill, Ludwig Bolzmann, Pierre Duhem, Einstein, Henri Poincaré, C.S. Peirce, Whitehead, Russell, Carnap, A.J. Ayer, Karl Popper, Thomas Kuhn, Imre Lakatos, Paul Feyerabend, Nelson Goodman, Bas van Fraassen, and numerous others. He lauds Popper for advancing beyond verificationism and Hume’s problem of induction, but faults both Kuhn and Popper for being unable to show that and how their work could lead nearer to the truth." —Dr. LLOYD EBY teaches philosophy at The George Washington University and The Catholic University of America, in Washington, DC "Maxwell's aim-oriented empiricism is in my opinion a very significant contribution to the philosophy of science. I hope that it will be widely discussed and debated." – ALAN SOKAL, Professor of Physics, New York University "Maxwell takes up the philosophical challenge of how natural science makes progress and provides a superb treatment of the problem in terms of the contrast between traditional conceptions and his own scientifically-informed theory—aim-oriented empiricism. This clear and rigorously-argued work deserves the attention of scientists and philosophers alike, especially those who believe that it is the accumulation of knowledge and technology that answers the question."—LEEMON McHENRY, California State University, Northridge "Maxwell has distilled the finest essence of the scientific enterprise. Science is about making the world a better place. Sometimes science loses its way. The future depends on scientists doing the right things for the right reasons. Maxwell's Aim-Oriented Empiricism is a map to put science back on the right track."—TIMOTHY McGETTIGAN, Professor of Sociology, Colorado State University - Pueblo "Maxwell has a great deal to offer with these important ideas, and deserves to be much more widely recognised than he is. Readers with a background in philosophy of science will appreciate the rigour and thoroughness of his argument, while more general readers will find his aim-oriented rationality a promising way forward in terms of a future sustainable and wise social order."—David Lorimer, Paradigm Explorer, 2017/2 "This is a book about the very core problems of the philosophy of science. The idea of replacing Standard Empiricism with Aim-Oriented Empiricism is understood by Maxwell as the key to the solution of these central problems. Maxwell handles his main tool masterfully, producing a fascinating and important reading to his colleagues in the field. However, Nicholas Maxwell is much more than just a philosopher of science. In the closing part of the book he lets the reader know about his deep concern and possible solutions of the biggest problems humanity is facing."—Professor PEETER MŰŰREPP, Tallinn University of Technology, Estonia “For many years, Maxwell has been arguing that fundamental philosophical problems about scientific progress, especially the problem of induction, cannot be solved granted standard empiricism (SE), a doctrine which, he thinks, most scientists and philosophers of science take for granted. A key tenet of SE is that no permanent thesis about the world can be accepted as a part of scientific knowledge independent of evidence. For a number of reasons, Maxwell argues, we need to adopt a rather different conception of science which he calls aim-oriented empiricism (AOE). This holds that we need to construe physics as accepting, as a part of theoretical scientific knowledge, a hierarchy of metaphysical theses about the comprehensibility and knowability of the universe, which become increasingly insubstantial as we go up the hierarchy. In his book “Understanding Scientific Progress: Aim-Oriented Empiricism”, Maxwell gives a concise and excellent illustration of this view and the arguments supporting it… Maxwell’s book is a potentially important contribution to our understanding of scientific progress and philosophy of science more generally. Maybe it is the time for scientists and philosophers to acknowledge that science has to make metaphysical assumptions concerning the knowability and comprehensibility of the universe. Fundamental philosophical problems about scientific progress, which cannot be solved granted SE, may be solved granted AOE.” Professor SHAN GAO, Shanxi University, China