Reflections on Ken Wilber's The Religion of Tomorrow
(2017) - Parts
INTEGRAL WORLD: EXPLORING THEORIES OF EVERYTHING
An independent forum for a critical discussion of the integral philosophy of Ken Wilber
Publication dates of essays (month/year) can be found under "Essays".
To read a response by one of the authors of Integral Ecology on the issue of plagiarism, click here.
works at the
Croatian Institute of History
, Zagreb, Republic of Croatia. He is the author of "Limits of Spiritual Enlightenment", "Two Roads Diverging: Integral Theory and Contemporary Science", "Twilight in the Integral World: Integral Theory and the Desintegration of Industrial Civilization", "Pitfalls of Wilberian Ecology: A Critical Review of Integral Ecology
" and "Paul Shepard and Integral Theory", all published on Integral World.
A Critical Review of "Integral Ecology"
Tomislav Markus (1969-2010)
I. Content and methodology of “Integral Ecology”
Integral Ecology is founded on an unjustifiable optimism and gives hopes which can't be materialized.
Integral Ecology is an emerging field that applies Ken Wilber's Integral Theory to environmental studies and research. The field has been pioneered, in the last several years, by integral theorist Sean Esbjörn-Hargens and environmental philosopher Michael Zimmerman. The authors maintain that Integral Ecology (IE) tries to integrate over 80 schools of ecology and 70 schools of environmental thought. It tries to integrate these approaches by recognizing that environmental things are the result of an observer using a specific method of observation to observe relevant aspect of nature. This post-metaphysical formula, in the authors opinion, is summarized as Who (the observer) x How (method of observation) x What (that which is observed).
In the authors's approach IE uses a framework of eight ecological worldviews (e.g.,eco-manager, eco-holist, eco-radical, eco-sage), eight ecological modes of research (e.g., phenomenology, ethno- methodology, empiricism, systems theory), and four terrains (i.e., experience, behaviors, cultures, and systems). The authors start from Wilber's AQAL (all quadrants, all levels) model, with its four fundamental terrains or dimensions: I (subjective, intentionality, individual experience), IT (objective, behaviour), WE (intersubjective, culture/ideas/worldviews) and ITS (interobjective, social and ecological systems). The authors argue that an integral approach means that all four spheres have to be taken into account and not only the two objective spheres, as modern science and many critics of modernity (from romantics to contemporary radical ecologists) did. But Integral Ecology puts a heavy emphasis on the subjective and intersubjective dimensions, even on some kind of nature mysticism. In the authors's approach, Integral Ecology is a consequence of the very often demand that human interior dimensions – personal experience and culture – receive good acknowledgement. For the authors,
“Integral Ecology is the study of subjective and objective aspecs of organisms in relationship to their intersubjective and interobjective environments at all levels of depth and complexity” (IE, 168-9, 173, 478).
The authors write that Integral Ecology is methods study of the subjective and objective parts of organisms who are in relationship to their intersubjective and interobjective parts of their environments. That means, for the authors, that Integral Ecology doesn't look for a new definition of ecology, but tries to find an integral interpretation of the common definition of ecology. In such ecology organisms and their environments have “interiority”. The authors argue that Integral Ecology also analyze “developmental stages” in nature and human beings. These include analyzing how people with different worldviews understand nature. For the authors, Integral Ecology tries to connect good insights from many and different perspectives into a theoretical framework which can have a practical meaning as well. For the authors, basic framework of Integral Ecology is based on Integral Theory, and on Ken Wilber's AQAL (all quadrant, all level) model. Integral Ecology is the result of many years of research exploring the many different ecological perspectives and their relevant methodologies.” The authors argue that many different worldviews must be represented, from natural and social sciences, philosophy, religion, cultural norms and values, etc. This is, the authors think, crucial if we want to develop good solutions to environmental problems. This is not, in authors's opinion, relativism, because some perspectives are more meaningful and better than others.
The authors argue that “Integral Ecology avoids 'gross reductionism' (the reduction of all reality to objective phenomena) and 'subtle reductionism' (the reduction of all interiors to interobjective phenomena)” and organizes all perspective into one coherent whole. For authors, “subjective and intersubjective dimensions must be interpreted on their own terms” and not reduced to (inter)objective phenomena (IE 6, 479). In book dozens of real-life applications and examples of this framework currently in use are examined, including three in-depth case studies by three different authors: work with marine fisheries in Hawai'i (by Brian Tissot), strategies of eco-activists to protect Canada's Great Bear Rainforest (by Darcy Riddell), and a study of community development in El Salvador (by Gail Hochachka).
Following Ken Wilber, the authors differentiate between „ascent tradition“ (mainly axial religions), which devalued the natural and social world in favor of some transcendental reality, and the „descent tradition“ of the modern age, which admits only the material world as reality. Descenders deny the possibility of Ascent, except as eternal horizontal technological and economic progress and affirm only two objective spheres (IT and ITS). That was the cause of the dignity (differentiation of art, morals and science and material progress) and disaster (exploitation and destruction of nature and indigenous nations) of modernity. Domination of descent tradition meant also rejecting spirituality and the interior perspective, and, hence, the creation of sense of meaningless and absurdity.
The authors criticize radical ecologists (environmentalists), especially deep ecologists, for „retro-romanticism“, „regressivism“, the idealization of „tribal/indigenous societies“, the negation of the „dignity of modernity“, possible totalitarian tendencies (eco-fascism or primacy of the whole over the individual organism), etc. In general, this is a repetition of Michael Zimmerman's – former heideggerian deep ecologist - critique from the 1990s and early 2000s. Even reformistic environmentalists are caught in the industrial grid of „flatland“ because they admit matter and energy as the only realities. The authors think that, instead of yearning for „back to nature“ or „unity with nature“ (this is social and personal regression), humans have to move forward to Spirit or higher levels of moral and spiritual development.
For the authors, Integral Ecology is, in some aspect, close to postmodernism because it emphasizes the importance of different perspectives, but it rejects postmodernistic extreme relativism, antiprogressivism and antimodernism. The authors maintain that the perspectivism of Integral Ecology means that all life has some kind of perspective or capability of noticing and prehending. The authors think that this inteority is developed the most in humans thanks to abstract reasoning, self-consciousness and language and in this sense biological evolution is progressive. For the authors, humans are not jut organic, but also noospheric beings.
II. Problems with wilberian ecology: critical remarks about “Integral Ecology”
It's a great irony that this so called "evolutionary" approach systematically avoids evolutionary biology and contemporary neo-darwinian theories.
In a previous article, "Two Roads Diverging" (Markus 2009b) I pointed out that „integral theory“ should be more accurately called "wilberian theory". Such is the case with „integral ecoloy“, which proper name should be "wilberian ecology" or even "orthodox wilberianism". The authors quote whole fragments from Wilber's works in detail, without any critical analysis. This method reminds one of orthodox marxists and their treatment of Marx/Engels theory. The limitations of wilberian theory are the limitations of this book as well.
Every human being and every scientist/philosopher has to have some particular perspective and this is not a bad thing. But the moral obligation of the scientist requires that this perspective has to be argued for as strongly as possible (ideally, presuppositions then stop to be prejudices and become testable hypothesis, then well-argumented theories) and that opposing perspectives must be mentioned and their rejection explained. That means that the authors don't represent a true „integral“ approach – perhaps because this is impossible? – but begin with some particular position and some fundamental positions. These positions – taken over, of course, from Wilber – are:
- idealism and subjectivism (the primacy of the „interior dimension“, worldviews, ideas and culture; not the negation of existence of the real world);
- cosmic progressivism (all fundamental changes, from the Big Bang to modern civilization are part of an „evolutionary advance“) and
- problem-solution („integral ecology“ as the „solution“ for ecological problems).
All three positions are taken for granted and they have the status of prejudices, not scientific hypotheses. This is inevitable, because the whole project of „integral ecology“ – in the authors' perspective, at least - starts as some kind of protest against scientific naturalistic and materialistic methodology. The idealistic approach presupposes a radical dualism between subjective and objective or interior and exterior, just as traditional dualism mind/body or soul/matter. Scientific naturalism, whatever its defects may be, is monistic and doesn't suffer from such problems.
What does the subjective analysis of ideas/worldviews/values mean ? If „interior dimensions“ aren't conditioned by material (biological, ecological and historico-social) conditions of human life, by what are they conditioned? Do they originate from some „spiritual intuition“, or from some inner dimension inside the human mind? If they are the product of objective dimensions then they can be explained objectively. If interior dimensions can't be reduced to objective dimension, how are they created? This reduction is possible and justifiable exactly because the interior dimension (self, experience, values, ideas etc.) is created through objective (darwinian evolution and historical-social changes) processes.
The authors's subjectivistic and idealistic approach leads into mysticism and irrationalism, ironically, in the name of „progress“ and the „dignity of modernity“. In the best case, this is some kind of thought-provoking, study-stimulating and very interresting speculative philosophy, but surely not some „integral theory“ which could „include“, much less „transcend“ science. To be sure, naturalistic and materialistic science has many constraints, but it is the best we have, because scientific objectivity is rooted in the cognitive structures of the brain, which is the product of eons of biological evolution (about that see: Markus 2009b). Speculative philosophy – which means a full return into traditional metaphysics – can't be the substitute for empirical science. Naturalistic science has, if nothing else, a rational and pretty much convincing explanation of the so called „interior dimensions“ of the human mind as a product of darwinian natural selection and long-term evolutionary processes. This is exactly the methodology of the darwinian ethologists, including Mark Bekoff who, ironically, wrote a very laudable foreword to this book. Belief in the autonomy of the „interior dimension“ leads either into irrational mysticism or rational metaphysics (inconsistent with a wilberian post-metaphysical approach).
The progressivistic approach is also a big defect of Integral Ecology. I earlier pointed out that anthropogenic problems, as the main characteristic of all civilizations, are the fundamental problem for every progressivistic interpretation of recent human history (Markus 2009a, 2009b). My general objections to Integral Theory (Markus 2009b) can be applied to Integral Ecology as well. The authors reject a regressive interpretation of recent human history but without any detailed and substantial analysis. Their short mention of Paul Shepard's theory is especially disappointing (IE 288-291). They even don't recognize a theory of bio-social discontinuity, a crucial point of Shepard's ecological theory and mention the catholic theologian Thomas Berry, quite a different thinker, alongside Shepard.
The authors think that, because all living beings alter their environment (which is, of course, true), every human work and artifact is „natural“ (IE 567). Not so. From a darwinian perspective, „natural“ is only what is evolutionary-tested or what is tested by natural selection in the eons of evolutionary time. For example, a beaver's dam is „natural“ not because it's part of nature (everything is so „natural“ and this is a pleonasm) but because it's an evolutionary-tested artifact which has its root in the beaver's genetic heritage; an ant-city is likewise natural, etc. But a human dam or human city is surely not natural in the sense that they are rooted in our evolutionary past or that they are part of our genetic heritage. This is the reason why a beaver's dam or ant-city is not problematic (ecologically or for the beaver's and ant's well-being, quite the opposite) in difference from a human dam or city. Industrial technology is unnatural not because it's technology – there is technology in hunter-gatherer society as well – but because it's part of industrial society, the most unnatural (that is, with the biggest adaptive gulf) social order in human history ever. Acknowledgement of the theory of bio-social discontinuity – perhaps through a better familiarity with Shepard's theory – could be helpful here.
The authors mention several books of environmental history, but there is very little historical analysis in their book. They think, basically, that the modern worldview („flatland“, „industrial ontology“ or scientific materialism) is the main culprit of ecological problems. But what about many ecological and other anthropogenic problems, including a sense of meaningless, in agrarian civilizations? There were certainly not industrial ontology, „flatland“ and modern science – or industrialism and machine technology, for that matter – in these societies. This is the reason why a scientific (not: speculative, as wilberian approaches often are) historical perspective so important. About these problems I already wrote in "Two Roads Diverging" (Markus 2009b). The authors mainly ignore hunter-gatherer societies in which there were no descent/ascent tradition and no special privilege for human beings. They use imprecise and scientificially useless terms, such as „indigenous“ or „tribal“ societies, a frequent defect in wilberian literature as well (Markus 2009b).
So, their critique of these societies is of a very poor quality and with very selective use of the scholarly literature, that is, they mention only those authors with a similar position (e.g. Edgerton 1992, Keely 1996, LeBlanc 2003), but not the others (e.g. Fry 2006, 2007, Ferguson 2006) or they put different authors in the same basket, even those who argue for quite opposite interpretations form theirs (e.g. C. Ponting and D. Hughes who think that the real root of the ecological crisis is neolithic domestification, but the authors mention them as an affirmation of their own position). They think that archeology, environmental history and other historical sciences have done much to dismantle a „naive understanding“ of „indigenous“ societies (IE 548). But, as I explained (Markus 2009b), no such consensus exists and many scientists argue for a position quite opposite of the authors'.
For the authors, personal and social regression is the worst sin of the radical ecologists, especially those who call for a „back to Pleistocene“ (IE 32-33). But, as Paul Shepard has pointed out in detail, this can be explained in a completely different way, as a protest against an unnatural social order (civilization in general, and industrial mega-cities in particular) and an affirmation of the natural ecological contex of human beings: a clean, organic and wild environment (Shepard 1996, 1998a, 1998b, 1998c, 1999). Pleading for a clean environment (clean water, air, food etc.) is surely not „regression“! But a clean environment is an ancient ecological context in which our ancestors were living for millions of years and which civilized (especially urban) humans desperately try to recover. If humans have genet needs for a clean environment they also have needs for an organic and wild environment, because it's our ecological contex too. And there's the rub, for when does such effort stop to be „correct“ and begin to be „regressive“? Or perhaps such effors are symptoms of a „higher stage of consciousness“ from the beginning? If so, then „primitive“ people don't have a need for a clean, organic and wild environment – or, perhaps, they have, but they aren't „rationally conscious“ of it, or… This is a big confusion for the civilized mind: fundamental needs of our nature – symptoms of our genetic adaptation to the hunter-gatherer life - can't be completely ignored, but progressivistic ideology and an apology of (modern) civilization intereprets them as „regression“, that is, as „atavistic“ remnants of our distant past which has to be „overcome“. All human behaviour is, in some sense, „regressive“ and „atavistic“ because it's all about the satisfaction of fundamental (genetic) needs, or, if that isn't possible (because humans live in an unnatural social environment), about finding substitutes. These substitutes can be the accumulation of political and economic power over other people and nature, consumerism or the construction of some collective illusion, like transcendental (celestial) beings, „historical progress“ or something else. I wrote about that in detail in a previous article "Limits of Spiritual Enlightenment" (Markus 2009a).
For the authors, ecological values depend on „higher moral development“ or „ecological conscioussness“. But hunter-gatherers have no „ecological consciousness (in the contemporary sense, at least) and they are presumably in the lowest level of (spiritual and material) „development“… but nevertheless they have the best ecological balance – from a clean and wild environment to long-term sustainability – of all human societies. And quite the opposite: industrial society – with the „highest level of development“ and the most „ecological consciousness – have the worst ecological balance. How is that possible? For the authors, that must be a great mystery but certainly not for those who accept the theory of bio-social discontinuity. The authors admit this (IE 649-654) but argue that this is so because of material factors (small population, simple technology etc.). Well, certainly yes, but this is a materialistic perspective, not „integral“ (read: wilberian) thinking. After all, what is crucial for the avoidance of ecological and other anthropogenic problems: „higher consciousness“ and lofty „moral development“ or suitable material factors, that is, a natural social and ecological context and the enforcing of evolutionary-tested behavior? Integral theory says the first, the theory of bio-social discontinuity says the second.
Prof. Esbjörn-Hargens and prof. Zimmerman think that a darwinian approach must be avoided in the case of human behavior if we can keep some moral constraints on human demographic expansion (IE 13). But this interpretation is an example of pop-darwinism, namely, a dark vision of nature as a bloody battle-field or "nature red-in-tooth-and-claw" because of the maximization of reproductive success. About this mistake, which originates from Darwin's misapplication of the malthusian hypothesis, I wrote in a previous article, "Two Roads Diverging" (Markus 2009b) New darwinian theories – in which the theory of bio-social discontinuity is present very frequently - authors mention only twice and incidentally. For example, sociobiology is mentioned as an example that ecological problems have their roots in human nature (IE 294), although many sociobiologists, including E. Wilson, point to the adaptive gulf, like Shepard. There are some other strange statements about neodarwinism, e.g. that biosemiotics is a „powerful critique of neodarwinism" (IE 570-1), surely completely new for neodarwinians (including myself).
Ignorance of (neo)darwinian theories is consistent also with the authors' tendency that modern science reduces everything to physics (the fallacy of physicalism). Physics can tell us nothing about «mind» or the «interior dimension», but darwinism and evolutionary biology are something else. So called human „interiority“ (or „spirituality“) is nothing but our genetic heritage and evolutionary past or what is popularly called „human nature“, evolved genetic traits, including our fundamental needs. Living beings, in difference from anorganic matter and energy, have an evolutionary heritage and genetic adaptation to some local habitat. This is quite different stuff than (mechanistic or quantum) physicalism.
It's a great irony that this so called "evolutionary" approach systematically avoids evolutionary biology and contemporary neo-darwinian theories. The antinaturalistic and idealistic approach of Integral Ecology creates many difficulties, for example: from where do ecological values come from? Integral Ecology maintains that ecological values come from interior – moral and spiritual – development. But what about other beings? That means, for example, that the need for a clean and healthy environment for humans is rooted in „interior development“ and for other beings in their evolutionary past. This is a strange and very unconvincing position. In fact, a natural and healthy environment for humans is exactly the same for humans as for any other species: an environment of evolutionary adaptation. The idealistic and subjectivistic approach is especially seen in the constructivistic position. For the authors, there is no such thing as biologically grounded human nature, only a self-constructed „self“ and an „interior experience“. This is an extreme version of subjectivistic and idealistic constructivism. Authors argue for pop-evolutionism, an un-scientific intepretation of evolution as a creative and „progressive“ process, which covers almost anything, from the Big Bang to social macrodynamics. I already criticized that perspective in "Two Roads Diverging" (Markus 2009b).
Methodological pluralism, with its 200+ perspectives, seems a great strength of Integral Ecology. But at a closer look this is not so because the authors take into account only specific aspects of other perspectives which can be accomodated into their perspective. Some perspectives – like the theory of bio-social discontinuity, which the authors don't even mention – are not compatible with Integral Ecology in even a very limited sense. Integral Ecology is a very specific perspective with several fundamental aspects:
- subjectivism, idealism and humanistic voluntarism,
- progressivism, especially with regard to recent human history,
- problem-solution (Integral Ecology as the „solution“ of ecological and other problems) and
- the probability of a sustainable industrial civilization.
One has to accept all of these four (and possibly some others) assumptions if Integral Ecology is to have some sense.
Of course, the authors are well aware that contemporary industrial societies are perhaps not sustainable, but Integral Ecology has sense only if they are sustainable (for worldcentric and planetcentric values are possible only in the global industrial civilization). The authors completely ignore fundamental events (such as peak oil) and fundamental processes (the end of the fossil fuel era) of our time. Only once they mention peak oil (IE 331), but not in the context of a serious theoretical analysis of contemporary societies, but in the fictive case of some „Mary Joe“ who believes that technology and a free market can be the solution for various problems, including the „peak oil crisis“. This is an incredible trivialization of the probably most important problem of contemporary industrial civilization. There is no mention, not even one book or article – and relevant literature is huge - about peak oil in their literature-list (except the interesting but outdated W. Catton's Overshoot) and one web-page (dieoff.org) in one footnote (IE 545).
Integral Ecology is founded on an unjustifiable optimism – a consequence of the subjectivic and idealistic approach with its fundamental importance of the „interior dimensions“ as „key to our future as species“ (IE 478), very much a Californian spin - and gives hopes which can't be materialized. Contrary to the authors' statements, it's basic position is not particularly new: the „solution“ is moral/spiritual „development“ and intellectual „enlightenment“ as a means for the „good“ use of technological and economic „progress“, or „progress“ in „interior dimensions“ as a good basis for „progress“ in „exterior dimensions“ (ecological modernization, sustainable development etc.). We have to be spiritually „enlightened“ to use modern technology „wisely“.
Not suprisingly, the authors mention „breakthroughs in alternative energy“ (IE 655) and they are certainly supporters of „alternatives“ and „renewables“. But it won't work and I have explained why in "Twilight in the Integral World" (Markus 2009c). For example, the authors argue that the percentage of poor people continues to shrink to the lowest recorded level (IE 153) – and that was written in the summer of 2008 (the time when their manuscript was finished), when the mega-crisis has exploded and the world financial system was at the brink of collapse. If our problems have thousands-year old roots (as the theory of bio-social discontinuity argues) and if industrial civilizations is not sustainable, there can't be a „solution“, neither technocratic nor idealistic, certainly not for the contemporary mega-crisis and the perfect storm (peak oil + climate change + a host of other „minor“ problems).
Ecological and other miseries are not „problems“ at all. They are conditions created by humans, which humans can't „solve“. In the short-term not because these „problems are created through several millieniums and in the long-term (a „solution“, say, 500 years from now?) not because this is not a human perspective at all. This is not fatalism (there are many things which can be done, individually and collectively), but a realistic assessment of the human predicament. About practical problems with wilberian thinking I already wrote in "Twilight in the Integral World" (Markus 2009c). There are other difficulties and problems in the book (e.g. the question of eco-fascism, the concept of a „post-natural world“ [another example of idealistic constructivism], bio-semiotics, the complete ignoring of the biggest tragedy of our time: the demographic explosion, worldcentrism as „fundamental feature of modernity“, a gross understatement of modern nationalism, a vague concept of the „pneumasphere“ etc.), but here I can't write about them in detail.
This book has some good sides, many thought-provoking statements, plenty of information, different perspectives, a refreshing interdisciplinary approach, interesting case-studies etc. It certainly deserves to be read carefully and more then once, because prof. Esbjörn-Hargens and prof. Zimmerman are serious ecological thinkers in their own right. A certain superficiality was probably inevitable because of the scope of the subject matter. But, in general, there is a significant gulf between the authors' ambition and their real achievement. It's laudable how much the authors have distanced themselves from the anthropocentrism and illusion of human exemptionalism, which are the main characteristics of the perennial tradition. Something more would probably mean the abandonment of a wilberian perspective altogether.
In the last few years Wilber has stopped responding (in fact, he didn't respond to some well-argumented critiques long time ago, e.g. David Lane's article „Wilber and the Misunderstanding of Evolution“ ) to his critics, because, he thinks, they constantly misinterpret his position (one more similarity between orthodox marxism and orthodox wilberianism: critics always distort the Master's view). Only internal critique(?) in the Integral Institute seems to be allowed and every external critique is seen as „misinterpretation“. I hope that the authors will take a more constructive, non-dogmatic approach, because they explicitly call on other thinkers to analyze the limitations and problems with integral ecology and integral theory in general (IE 552). This review is one such attempt. The lenght of this review is a symptom of my conviction that their book, despite many problems and omissions, is a well-written, serious and inspiring work. I had a sense that I am better informed and educated after reading their book. And in other cases authors compelled me to think harder about my main convictions and statements. I am grateful to them for that.
 Sean Esbjörn-Hargens – Michael Zimmerman, Integral Ecology: Uniting Multiple Perspectives on the Natural World, Boston: Integral Books. Quotation marks denote sentences or part of sentences literary quoted from book “Integral Ecology”. Reviewer mention his other works, published previously in the “integral world” because of shortening of review (f. e. instead of explanation what certain concepts – like theory of bio-social discontinuity or oil peak mean – reviewer mention his relevant articles about these topics)
Edgerton, R. 1992. Sick Societies, New York: Free Press
Ferguson, B. 2006. «Archeology, Cultural Anthropology and the Origin and Intensification of War» (Arkush-Allen 2006:469-524)
Fry, D. 2006. Human Potential for Peace, Oxford: Oxford U. P.
Fry, D. 2007. Beyond War, Oxford: Oxford U. P.
Keeley, R. 1996. War Before Civilization, Oxford: Oxford U. P.
LeBlanc, S. 2003. Constant Battles, New York: St. Martin's Press
Markus, T. 2009a. «Limits of Spiritual Enlightenment» (www.integralworld.net)
Markus, T. 2009b. «Two Roads Diverging» (www.integralworld.net)
Markus, T. 2009c. «Twilight in the Integral World» (www.integralworld.net)
McIntosh, S. 2007. Integral Consciousness and the Future of Evolution, St. Paul: Paragon House
Reynolds, B. 2006. Where Wilber At?, St. Paul: Paragon House
Shepard, P. 1996. Traces of an Omnivore, Washington: Island Press
Shepard, P. 1998a. Nature and Madness, Athens: University of Georgia Press
Shepard, P. 1998b. Coming Home to the Pleistocene, Washington: Island Press
Shepard, P. 1998c. The Tender Carnivore and the Sacred Game, Athens:University of Georgia Press
Shepard, P. 1999. Encounters with Nature, Washington: Island Press
Visser, F. 2003. Ken Wilber: Thought as Passion, Albany: SUNY Press
Wilber, K. 2000. A Brief History of Everything, Boston: Shambhala
Zimmerman, M. 1994. Contesting Earth's Future, Berkeley: University of California Press
Zimmerman, M. 1998. „A Transpersonal Diagnosis of the Ecological Crisis“ (D. Rothberg & S. Kelly, eds. Ken Wilber in Dialogue, Wheaton: Quest Books 180-206)
Zimmerman, M. 2000. «Possible Political Problems of Earth Based-Religiosity» (E. Katz, A. Light & D. Rothberg, eds. Beneath the Surface: Critical Essays in the Philosophy of Deep Ecology, Cambridge Mas.: MIT Press, 169-194)
Zimmerman, M. 2001. «Ken Wilber's Critique of Ecological Spirituality» (D. Barnhill & R. Gottlieb, eds. Deep Ecology and World Religions, Albany: SUNY Press., 243-269)