Radical constructivism

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The Radical Constructivism is a position of epistemology , clearly from other constructivisms different.

One of the basic assumptions of radical constructivism is that personal perception cannot produce the image of a reality that exists independently of the individual, but that reality means for each individual only a construction of his own sensory stimuli and his memory performance. Therefore objectivity in the sense of a correspondence between the perceived (constructed) image and reality is impossible; every perception is entirely subjective. This is the radicalism (uncompromising) of radical constructivism.

Ernst von Glasersfeld is considered the founder of radical constructivism . According to von Glasersfeld, the core problem of Western epistemology is : “Wanting to recognize what lies outside the world of experience.” According to radical constructivism, this problem cannot be solved, but rather avoided; Von Glasersfeld had found suggestions for this in the work of the psychologist and epistemologist Jean Piaget : Piaget had already stated “that the cognitive structures that we call 'knowledge' should not be understood as 'copies of reality', but rather as the result of Adaptation. "E. v. Glasersfeld coined the term viability for this . This term distinguishes between “an iconic relationship of correspondence or reflection” and a “relationship of fit”. This overcomes the illusion that "the empirical confirmation of a hypothesis or the success of a course of action means knowledge of an objective world."

The biophysicist and cyberneticist Heinz von Foerster and the neurobiologists Humberto Maturana and Francisco Varela are also considered to be the main representatives of radical constructivism , even if the latter two do not want to be called constructivists. Maturana and Varela developed the concept of autopoiesis , which also radiated into the humanities and social sciences, e.g. B. in the 1980s in the sociological systems theory of Niklas Luhmann . Heinz von Foerster formulated a cybernetic epistemology, i. H. a theory of knowledge acquisition based on cybernetics.


Ernst von Glasersfeld already identified constructivist ideas among the pre-Socratics . The sophists and skeptics had already compiled evidence of the unreliability of the human sense organs . According to von Glasersfeld, Plato's allegory of the cave is an illustration of reality. But apophatic theology also took the view that God could not be grasped with human terms, since these all stem from human experience. In the 9th century, the scholar Johannes Scottus Eriugena took the view that man could not determine his nature in such a way that he would be able to say what he was. and the 14th century Dominican Meister Eckhart , who was also in the tradition of negative theology, asks God to free him from the (always constructed) idea of ​​God, since that also belongs to the created worldly structure: “I ask God that he make me even with God; for my essential being is above God, insofar as we understand God as the beginning of creatures ”. John Locke used the term reflection in the same way as Piaget used it in the 20th century. George Berkeley believed that numbers were a creature of the mind and therefore depended entirely on the viewer. David Hume concluded: "So when we say that one thing is linked to another, we only mean that the two objects are linked in our thoughts and that these produce our conclusions, thereby mutually proving their existence". Giambattista Vico , one of the first constructivists in the Glasersfeld sense, pointed out in 1710 that the words verum (true) and factum (fact) were interchangeable for the Latins. Immanuel Kant pointed out: “So far it has been assumed that all of our knowledge must be based on objects; [...] One should therefore try to see if we do not get on better in the tasks of metaphysics by assuming that the objects must be based on our knowledge ”. Hermann von Helmholtz wrote that the principle of causality is in fact nothing other than the prerequisite for regularity in all the phenomena of nature.

The radical constructivism emerged as a consequence of the results of the above. Scientists and the scientific zeitgeist in the 1970s. In 1974 von Glasersfeld first linked the word “radical” with the genetic epistemology of Jean Piaget. His aim was to draw the conclusions from Piaget's genetic epistemology. Von Glasersfeld expanded Piaget's approach to include the development of the ego, the function of language and communication, and the application of constructivist principles in arithmetic lessons.

In 1978 the conference “Construction of Realities” took place in San Francisco, organized by Förster and Varela. The focus was on the conviction of the participating scientists from a wide variety of disciplines such as biology, sociology, political science, logic, linguistics, anthropology and psychotherapy that traditional epistemology could no longer be upheld. Radical constructivism became known to the general public primarily through the publications of Paul Watzlawick ( Guide to Unhappiness , The Invented Reality , How Real Is Reality ).

Radical constructivism developed its greatest effect in the field of philosophy of science . Here radical constructivism can be located in the context of relativistic or pragmatic approaches, since like them it rejects the absolute claim of scientific knowledge. In particular, the theory of the observer was widely accepted. The concept of the observer alternates between its traditional meaning, the abstract role of an authority in control systems (see observer ) and in the sense of scientific observation . While in realism the observer looks at the world from a neutral point of view, does not see himself as part of the world while observing, wants to exclude the observer's influence, radical constructivism points out that this point of view cannot be taken: the observer is always Part of the world and always has a subjective point of view and thus always influences the observation itself.


Radical constructivism is an "unconventional way of looking at the problems of knowing and cognizing". Radical constructivism says that all knowledge exists only in the heads of individuals and that a thinking individual can only assemble his knowledge on the basis of his own experience through his body senses. No individual can exceed the limits of his or her personal experience. The knowledge of an “objective knowledge”, the truth, the ontological reality is therefore not possible. Even if many people successfully use the same scientific knowledge for themselves, it does not become objectively true.

Every perception is the result of a sensory stimulus and its processing in the nervous system. The change of sensory data into electrical impulses in the nervous system makes it impossible to draw any conclusions about the nature of the thing itself , i. H. on the original nature of the triggering agent . “Nobody will ever be able to compare the perception of an object with the postulated object itself that is said to have caused the perception”, i.e. H. Perception and knowledge are constructive, not depicting activities.

Knowledge does not provide a picture of the real world, it only provides a subjective construction that “fits” the world (like a key fits a lock). It is like a "conceptual tool whose value is only measured by its success in use". This agrees with Plato's allegory of the cave and Kant's point of view: “The things that represent our senses and our intellect are only appearances; i., objects of our senses and our intellect, which are the meeting of the occasional causes and the effect of the intellect. "The" occasional cause "is what our organs of perception receive, transmit in the form of electrical impulses to the brain and from there to one Image of the world (or part of the world) is interpreted, put together, just constructed.

The brain is not a “monitor” that converts incoming signals into an image, but rather the entire experience of the individual flows into the construction during the interpretation.

“The memory is the most important sense organ: Most of what we perceive comes from memory. We always perceive through the 'glasses' of our memory, because what we perceive is decisively co-determined by previous perception. "

Basic principles

Basic principles of radical constructivism are - with reference to Piaget:

  1. “Knowledge is not absorbed passively, neither through the sense organs nor through communication.
  2. Knowledge is actively built up by the thinking subject.
  3. The function of cognition is adaptive , in the biological sense of the word, and aims at fit or viability .
  4. Cognition serves to organize the subject's world of experience and not to 'cognize' an objective, ontological reality. "

In contrast to Kant's epistemology, radical constructivism sees itself as a theory of knowledge. Knowledge is therefore "a tool that has to be judged according to its usefulness and is not to be viewed as a metaphysical design."

Basic concepts

Piaget explains knowledge biologically. From the systematic observation of children he understands “cognition as a biological function and not as the result of impersonal, universal and ahistorical factors”. The radical break with the usual philosophical approach of epistemology is that it is not about an ontological explanation of the world, but about the explanation of the world as the organism experiences it.

The decisive factor is the child's ability to remember objects in their development. Von Glasersfeld calls this process "re-presentation", the object is presented again. The object is reconstructed after a past experience from memory at the time of re-presentation.

Another crucial step in the child's development is taken when an object is given an existence of its own. The object is no longer considered to have disappeared if the child does not see it ([object permanence]). This means that the object can also move, age, change, and is still recognized. It is also recognized as an object in causal processes.

The child now associates general expectations with this object. If these expectations are met with only minor deviations, radical constructivism calls this process “ assimilation ”. The experience with this object is confirmed, reinforced, von Glasersfeld also speaks of a reinforcement of the "recognition pattern".

If this expectation is not met, a disturbance arises which radical constructivism calls " perturbation ". This perturbation leads to a change in the existing recognition pattern. A new recognition pattern is generated taking into account the new conditions, so that the expectations in the situation are met again in the future. Radical constructivism calls this process " accommodation ". The child has learned something - the perturbation has been eliminated.

Through the process of eliminating perturbation through accommodation, the state of equilibrium is restored for the individual. Radical constructivism calls this process " equilibration ". Von Glasersfeld sees this as a novel learning theory. According to von Glasersfeld, equilibration works like a rule system with negative feedback and applies not only to the conceptual area, but also to the area of social interaction . Social interactions are a much richer source of perturbations and the subsequent accommodations than the disturbances caused at the sensorimotor level.

Schemes of action

Von Glasersfeld concludes from this that cognitive organisms must have at least four characteristics:

  1. the ability, and furthermore the tendency, to see repetition in the stream of experience
  2. the ability to remember, to recall experiences, i.e. to represent
  3. the ability to make comparisons and judgments in terms of similarity and difference
  4. the ability to prefer certain experiences to others and thus to have elementary value criteria

The individual therefore builds schemes of action in order to deal adequately with the world.

On the sensorimotor level, these action schemes serve survival. On the mental level, the level of the “reflective abstraction” of the formation of viable terms, action schemes can be tried out and tested for their viability . At this level the individual can therefore carry out "thought experiments". Experiences can be freely shared, combined and regrouped.

The individual is inundated with sensory impressions every moment and therefore always actively chooses what is the central object of his attention. This process does not have to be consciously controlled. But attention can also rest on thought experiments, that is, on the activity of the mind. The individual is an actor in both situations.

A concept of the I.

Just as an individual constructs his picture of the world bit by bit from his experiences, his picture / knowledge of his own I can also be built up in a similar way. In general experience, at ICH we think of a person's individual identity or continuity. This I is the place of all experience and at the same time something actively acting. It can move and thus influence its perception. "Within certain limits, it can even decide whether or not to have an experience."

When the “basic I” of a person is developed, the “social I” develops during puberty. As actors, we take on specific behavioral patterns and roles that become essential and unmistakable parts of what we then call our selves.

According to von Glasersfeld (1996), constructivism can only offer viable concepts of the I in which it is the place of experience via the sense organs. "The ego as an active agent of construction or the ego as the place of subjective consciousness seems to be a metaphysical assumption and is therefore outside the realm of empirical construction." He states that he (1996) is not aware of any viable explanation of consciousness.


Ernst von Glasersfeld concludes: "Constructivism cannot produce ethics". Nevertheless, radical constructivism has ethical consequences, such as the fact that responsibility for all doing and thinking must be attributed to the person who does and thinks it: the individual . The individual himself can therefore act ethically. Glasersfeld's statement only relates to the theory itself. He also emphasizes that he is not aware of any epistemological theory from which ethics can be derived.

Von Glasersfeld sees a prerequisite for ethical action, however, in the fact that individuals are dependent on other individuals. Only in this way can a person ultimately achieve “confirmed knowledge”. He has to acknowledge that other people like himself are “autonomous designers”. If he were to force them to adopt his ideas, he would automatically destroy the possibility of receiving this confirmation of his ideas. In contrast to other philosophies, radical constructivism can at least give this one “fundamental” reason for recognizing the human condition of other people.

For Heinz von Foerster, ethics is an attempt to standardize. He sets his ethical imperative like this: "Heinz, always act in such a way that the number of options increases!"

The fact that (radical) constructivism is irrelevant for ethical action, but countless action theories such as psychology , psychotherapy , counseling , pedagogy , social work , organizational development refer to it as a basic theory, leads to an argumentation gap such as this "stimulus relationship" of epistemology and Action theory should look like. Holger Lindemann has developed a general multi-level model for this purpose, which clarifies the transitions between explanatory knowledge, orientation knowledge and practical knowledge, without the theoretical foundations having a normative effect on pragmatic aspects of the practical sciences.

The others

From the point of view of radical constructivism, other people are a) constructions of an individual through which they form expectation patterns and b) part of the world “out there”. In the collision with the “world out there” (= reality) the expectation schemes of the individual can be fulfilled or disappointed and in this case perturbations arise. Von Glasersfeld calls this: perturbations of a social nature. They are much more frequent than other occasions of perturbations. The construction of the other is adapted by the individual.

From the point of view of radical constructivism, this also makes it clear that knowledge is only available as a construction of the respective individual; other individuals also have knowledge, e.g. B. from the same processes, but their own constructions above, which are at best compatible with their own constructions. Such knowledge has second-order viability (one does not speak constructivistically of “confirmed facts” of “shared knowledge”). It is "intersubjective".

Other representatives

Ernst von Glasersfeld developed radical constructivism from his own experience with language and in dealing with the philosopher Ludwig Wittgenstein . In the works of Piaget he finally found a key to epistemology, the theory of knowledge, which he called "radical constructivism".

Other scientists arrive at constructivist theories in completely different ways.

Heinz von Foerster

Heinz von Foerster , professor of biophysics and long-time director of the legendary Biological Computer Laboratory in Illinois, formulated a theory of knowledge acquisition based on cybernetics that explains how human knowledge can arise without access to an objective reality.

Heinz von Foerster draws attention to the principle of undifferentiated coding: “The reaction of a nerve cell does not encode the physical characteristics of the agent that causes its reaction. Only the 'so much' at a certain point in my body is encoded, but not the 'what'. "

Recognition as an activity of the nervous system is interpreted by him as calculating a reality. With calculation is meant a constant process that never leads to a final result. Knowledge does not exist statically, in the form of a stable representation of reality or in a molecular form, but is recalculated over and over again; von Foerster describes this form as "operational knowledge."

“In order to recognize a table and say“ This is a table ”, I don't have to have the letters TISCH in my brain, nor does a tiny representation of a table (or even the“ idea ”of the table) need to sit somewhere in me. But I need a structure that calculates the various manifestations of a description for me ”.

Heinz von Foerster is thus revising his original idea of ​​a memory based on molecules in favor of an “operative memory” that recalculates memory over and over again.

Maturana and Varela

Humberto Maturana is a neurobiologist and developed a theory of the existence of living systems as autonomous dynamic units. Since 1970 he has been working as a neurophysiologist with epistemological problems via the path of the "biology of cognition". Together with Francisco Varela , he was instrumental in developing the concept of autopoiesis. Varela is a biologist, philosopher and neuroscientist. Neither Varela nor Maturana want to be called constructivists.

Maturana sees language more in terms of its social function. With his statements on social coupling and culture, he crosses a line that Ernst von Glasersfeld clearly draws: From (radical) constructivism one cannot and should not derive any values or ethics. In principle, an epistemology cannot achieve that.

The assumption by Maturana and Varela that every individual constructs his or her subjective world without access to an objective reality does not mean that there is no social control of the constructional achievements among people (see also: The tree of knowledge ). Language enables people to have areas of so-called consensuality (in the sense of an agreement on the nature of a circumstance or thing) and the supra-individual creation of meaning in which they exist and which are reality for them. Maturana and Varela call this area the "area of ​​social coupling".

Human individuals create a "second dimension of reality" by assuming that their own constructions are similar to those of others through the use of terms, and they experience themselves as part of a community by assuming and claiming that their own constructions are those of others at least largely correspond. In addition to their own singular world, they also construct a social world of the community that is characterized by linguistic behavior coordination and creates multidimensional contexts of meaning (politics, religion, customs, science, etc.) that they can call culture .

The experience of stability and continuity of one's own constructed reality is dependent on the confirmation of this perception by other observers beyond the sensual perception of the individual . This consensuality is worked out through language; building up common constructions in the coexistence of human observers leads to the building of socially accepted realities, e.g. B. a common ethical system or "equal" views on a matter.

Stability is achieved by “people constantly imposing their own coordination of sensory experiences on other people, whereby this reciprocity leads to a confirmation and stabilization of the constructed reality”.

A child learns language from a radical-constructivist view not as a system of “information transfer”, but as a form of “behavioral coordination”. It has to learn through trial-and-error strategies to combine the multitude of verbal utterances of the adults with the desired modes of reaction on its part. The words cutlery / democracy coordinate our actions with regard to what a person does when dealing with cutlery / democracy. The word “cutlery” and all other words do not convey information, but something specific is triggered in the recipient, which is determined by its structure and thus indirectly by its socialization.

However, cultural realities are not absolutely imperative for humans, because they have the opportunity to reflect on them (= to make sure of their constructional character) and to redefine them. The determining effectiveness of the cultural techniques mediated by socialization is broken by the cognitive autonomy of the individual.

According to Maturana, communication is defined as “the mutual triggering of coordinated behavior among the members of a social unit”.

The constructivist approach thus rejects the idea that information in the traditional sense is transmitted from a sender to a receiver through communication, because "this idea is based on non-structure-determined units for which interactions have a prescriptive (instructing) character, which would mean that what happens in a system is determined by the perturbing agent and not by the structural dynamics of the system . Yet even in everyday life it is obvious that communication does not take place like this: each person says what they say and hears what they hear according to their own structural determination; that something is said does not guarantee that it will be heard. […] The phenomenon of communication does not depend on what is transmitted, but on what happens in the recipient. And this has little to do with 'transmitted information'. "

The central characteristics of human social systems are the linguistic "area of ​​co-existence" created by their members and the "expansion of the properties of its members". From a biological point of view, it is the other way around on the level of social systems than on the level of living systems: “The organism restricts the individual creativity of the units (= organs) that make it up, since these units exist for the organism. The human social system expands the individual creativity of its members, since the system exists for the members. ”In constructivist anthropology, the function of language and the social systems arising from it is the expansion of individual development possibilities within ontogeny , which means an evolutionary advantage. If human communities use coercive mechanisms to stabilize all behavioral dimensions of their members, so the reverse conclusion of the authors, these systems lose their “social quality”, since they do not expand the development possibilities of their members, but limit it.

For Maturana and Varela, culture means the entire network of ontogenetically acquired behavioral patterns that exhibit cross-generational stability within the communicative dynamics of a social milieu. The coupling between the generations as well as the mixture of dynamics and continuity within different lines of tradition arise through the constant selection of viable behaviors, through imitation and through the aforementioned ambiguity of linguistic communication. “So cultural behavior does not arise from a special mechanism; it represents only a special case of communication. The special thing about it is that it arises as a consequence of a social life over generations, whereby the members of this social structure are constantly being replaced by new ones ”.


Constructivism is differentiated from falsificationism and solipsism . It is true that the process of developing new and better theories corresponds to that which is assumed in the context of falsificationism. However, it is denied that these theories can describe reality better (or at all). Since we do not know reality, it cannot be said that this or that theory describes this reality better. Does Newton or Einstein describe reality better? It can only be said that there are fewer contradictions with the theory of relativity than with Newton's physics.

The instrumentalism that emanates in large parts of it, theories developed evolutionarily and inappropriate models of reality would thus replaced necessarily by more convenient, closer related to the real ideas of the world, opposes constructivism that an approximation to an objective reality through better Theories cannot be reached because no comparison with objective reality is possible.

There is also a clear proximity to Kant's epistemology. For Immanuel Kant , too , the “thing in itself” - as it really is - is not recognizable, but the thing as it is for us humans (cf. Critique of Pure Reason ). With Kant there is a way that leads from things as they appear to us to our conceptions of things. Here radical constructivism differs from Kant: There is no way from our perception to any objective conceptions of things, because a comparison of the appearance of things with the thing in itself is not possible and so “objectivity” cannot be achieved at all.

Even within constructivist discourses, it is not always easy to assign individual authors to radical constructivism or one of the numerous other constructivisms. In recent years this has been made more difficult by the fact that various representatives of constructivist positions have modified their theories - Gerhard Roth , for example, now expressly names his position as a neurobiological constructivism; Siegfried J. Schmidt claims with a book title the “farewell to constructivism” and Björn Kraus has developed a more socially theoretical relational constructivism based on a radical constructivist position . At least with Roth and Kraus, the theoretical foundations are still radical constructivist.


The concept of radical constructivism also meets with criticism in epistemological treatises. According to Rainer Schnell and others, the main criticized points can be summarized as follows: The justification for radical constructivism is based on scientific findings which, according to its own definition, cannot be valid, because a non-existent access to reality, as postulated by radical constructivism, cannot be recognized as part of reality. Thus radical constructivism has a "self-application problem". Another accusation is that radical constructivism denies the existence of a reality independent of human knowledge. So it would be a form of solipsism .

See also


  • Ernst von Glasersfeld: The Radical Constructivism. Ideas, results, problems. Suhrkamp, ​​Frankfurt am Main 1996, ISBN 3-518-58230-5 . (TB 1997)
    Original title: Radical Constructivism, A Way of Knowing and Learning. London 1995.
  • Ernst von Glasersfeld: Knowledge, Language and Reality. Working on radical constructivism. (= Philosophy of science, science and philosophy. 24). Vieweg, Braunschweig, Wiesbaden 1987, ISBN 3-528-08598-3 .
  • Ernst von Glasersfeld: Aspects of Constructivism: Vico, Berkeley, Piaget. In: Gebhard Rusch & Siegfried J. Schmidt [ed.]: Constructivism: history and application. Delfin 1992. pp. 20-33. Frankfurt a. M., Suhrkamp, ​​1992, ISBN 978-3-518-28640-1 .
  • Ernst von Glasersfeld's introduction to radical constructivism . In: P. Watzlawick [ed.]: The invented reality. Pp. 16-38, Munich, Piper, 1994. ISBN 978-3-492-10373-2 .
  • Ernst von Glasersfeld: Beyond the Limits of Understanding. Benteli, Bern 1996, ISBN 3-7165-1004-1 .
  • Ernst von Glasersfeld: Paths of Knowledge. Constructivist explorations through our thinking. Edited and with a foreword by Hans Rudi Fischer . Carl Auer Systems, Heidelberg 1996, ISBN 3-89670-004-9 .
  • Ernst von Glasersfeld: Between languages. A Personal History of Radical Constructivism . Audio CD, conception and direction: Klaus Sander. supposé, Cologne 2005, ISBN 978-3-932513-63-3 .
  • Ernst von Glasersfeld, Heinz von Foerster: How we invent ourselves. An autobiography of radical constructivism. 9th edition. Carl Auer, Heidelberg 1999, 2004, ISBN 3-89670-116-9 .
  • Heinz von Foerster, Ernst von Glasersfeld, Peter M. Hejl: Introduction to Constructivism. (= Publications of the Carl-Friedrich-von-Siemens-Stiftung. 5). Piper, Munich, Zurich 1992, ISBN 3-492-11165-3 . (Piper-TB, 2006)
  • Heinz von Foerster, Bernhard Pörksen; Hans Rudi Fischer (Ed.): Truth is the invention of a liar. Conversations for skeptics. 8th edition. Carl Auer, Heidelberg 2008, ISBN 978-3-89670-096-4 .
  • Heinz von Foerster: view and insight. Attempts at an operational epistemology. (= Philosophy of science, science and philosophy. 21). Vieweg, Braunschweig, Wiesbaden 1985, ISBN 3-528-08468-5 . (Carl Auer, Heidelberg 1999, ISBN 3-89670-094-4 )
  • Heinz von Foerster, Monika Bröcker: Part of the world. Fractals of an ethic or Heinz von Foerster's dance with the world. 2nd Edition. Carl Auer, Heidelberg 2007, ISBN 978-3-89670-557-0 .
  • Heinz von Foerster, Bernhard Pörksen : Truth is the invention of a liar. Conversations for skeptics. Carl Auer Systems, Heidelberg 1998, ISBN 978-3-89670-214-2

Further and further reading:

Other literature with predominantly content-related reference to radical constructivism (law)

  • Kye I. Lee: The structure of the legal decision from a constructivist point of view , Mohr Siebeck, Tübingen 2010, ISBN 978-3-16-150245-3 .
  • Oliver Harry Gerson: The right to accuse - procedural balance in criminal proceedings through communicative autonomy , De Gruyter, Berlin / Boston 2016, ISBN 978-3-11-048980-4 .
  • Hans-Joachim Strauch: How really do we see reality? On the benefits of radical constructivism for legal theory and practice , JZ (Juristic newspaper) year 2000, pp. 1020-1029.

Other literature with predominantly content-related reference to radical constructivism (social work / educational sciences)

  • Björn Kraus : Constructivism, communication, social work: Radical constructivist considerations on the conditions of the socio-educational interaction relationship , Carl-Auer-Systems-Verlag, Heidelberg 2002, ISBN 978-3-89670-312-5 .
  • Björn Kraus: Recognize and decide. Basics and consequences of an epistemological constructivism for social work , Beltz Juventa, Weinheim / Basel 2013, ISBN 978-3-7799-2854-6
  • Holger Lindemann : Constructivism and Pedagogy. Basics, models, ways to practice , Reinhardt, Munich 2006, ISBN 978-3-497-01843-7

Critical Literature * Paul Boghossian : Fear of the Truth: A Plea against Relativism and Constructivism. Suhrkamp, ​​Frankfurt 2013, ISBN 978-3-518-29659-2 .

Web links

Individual evidence

  1. Ernst von Glasersfeld: Construction of Reality and the Concept of Objectivity. In: Heinz von Foerster u. a .: introduction to constructivism ; Publications of the Carl-Friedrich-von-Siemens-Stiftung, 5; Munich: Piper, 1992, ISBN 3-492-11165-3 , p. 29.
  2. Von Glasersfeld, 1992, p. 29.
  3. All three quotations: Von Glasersfeld, 1992, p. 30.
  4. ^ Ernst von Glasersfeld: The radical constructivism ; o. V., Frankfurt am Main 1996, p. 59. - As Suhrkamp Taschenbuch Wissenschaft: 1997 (1st edition)
  5. ^ Ernst von Glasersfeld: The radical constructivism. P. 61.
  6. ^ Ernst von Glasersfeld: The radical constructivism. P. 61 f.
  7. ^ Ernst von Glasersfeld: The radical constructivism. P. 62.
  8. ^ J. Quint, Meister Eckehart: German sermons and tracts. Zurich 1979, Sermon 32, p. 308.
  9. ^ Ernst von Glasersfeld: The radical constructivism. P. 67 ff.
  10. ^ Ernst von Glasersfeld: The radical constructivism. P. 70 ff.
  11. Quoted from Ernst von Glasersfeld: The radical constructivism. P. 72.
  12. ^ Ernst von Glasersfeld: The radical constructivism. P. 75.
  13. Quoted from Ernst von Glasersfeld: The radical constructivism. P. 79.
  14. ^ Ernst von Glasersfeld: The radical constructivism. P. 83.
  15. ^ Ernst von Glasersfeld: The radical constructivism. P. 49.
  16. Von Glasersfeld, 1996, p. 22.
  17. Ernst von Glasersfeld: Construction of Reality and the Concept of Objectivity. In: Heinz von Foerster u. a .: introduction to constructivism ; Publications of the Carl-Friedrich-von-Siemens-Stiftung, 5; Munich: Piper, 1992, ISBN 3-492-11165-3 , p. 12.
  18. Von Glasersfeld, 1992, p. 30.
  19. Von Glasersfeld, 1996, p. 55.
  20. Immanuel Kant, in: Kant, Werke, Volume VII, p. 71.
  21. Wolfgang Pahl gives this relationship between "occasional cause" and the scope of interpretation of the brain as 25:70. Wolfgang Pahl: Rethink instead of planting apple trees. Plea for an evolutionary worldview. S. 82. Cf. also the statements of the brain researcher Gerhard Roth in: Jürgen Nakott: News from the brain research - Everyone is wrong who thinks he knows what someone else is thinking ( Memento from January 17, 2002 in the Internet Archive ); Image of science
  22. Gerhard Roth: The constructive brain: Neurobiological foundations of perception and knowledge. In: Siegfried Schmidt (Ed.): Cognition and Society. The Discourse of Radical Constructivism 2 ; Frankfurt am Main, 1992, p. 317; M. Spitzer: Learning. 2007, p. 54, confirms this: For every 10,000,000 connections in the brain, only one comes from or to the sense organs.
  23. Ernst von Glasersfeld, 1996, p. 96.
  24. Ernst von Glasersfeld, 1996, p. 97.
  25. von Glasersfeld, 1996, p. 101.
  26. Ernst von Glasersfeld, 1996, p. 121.
  27. Ernst von Glasersfeld, 1996, p. 123.
  28. a b Ernst von Glasersfeld, 1996, p. 204.
  29. Ernst von Glasersfeld, 1996, p. 210.
  30. ^ Ernst von Glasersfeld in the Third Siegen Conversation, printed in: Ernst von Glasersfeld: Radikaler Konstruktivismus. 1996, pp. 335-336.
  31. Ernst von Glasersfeld, 1996, p. 209.
  32. Heinz von Foerster, Poerksen Bernhard: Truth is the invention of a liar. Conversations for skeptics. 3. Edition. Heidelberg: Carl Auer, 1999, p. 24. Von Foerster consciously puts his own first name in front of the ethical imperative because he does not want to create a categorical imperative that should be universally valid, but only puts a guiding principle in words. Heinz von Foerster: Understanding Understanding ; 2002, p. 303.
  33. Bernhard Poerksen: The observation of the observer. An epistemology of journalism . UVK, Konstanz, 2006, pp. 64-65.
  34. Holger Lindemann: Constructivism, system theory and practical action. An introduction to educational, psychological, social, societal and operational fields of action . Vandenhoeck & Ruprecht, Göttingen, 2019, pp. 249–258.
  35. Holger Lindemann, 2019, pp. 259–289.
  36. Ernst von Glasersfeld, 1996, p. 196ff.
  37. ^ Heinz von Foerster: view and insight. Attempts at an operative epistemology ; Braunschweig, Wiesbaden: Vieweg, 1985, p. 29.
  38. ^ Heinz von Foerster: view and insight. Attempts at an operative epistemology ; Braunschweig, Wiesbaden: Vieweg, 1985, p. 25 f.
  39. Heinz von Foerster, Ernst von Glasersfeld: How we invent ourselves. An Autobiography of Radical Constructivism ; 2004.
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