Von Glasersfeld's answers
July  2001









Dr. Glasersfeld
In working with students epecially in middle school science, I have found one way of teaching that ascribes to the theory of constructivism. I do notice a jump from the concrete to formal operation in terms of their thinking. I would like to ask how can I measure this change in students cognitive development? Is there a measure that you would suggest?

Thank you, mwarumba email: mikanjuni@yahoo.com 


Dear Mr. mwarumba,
I'm afraid measurement and testing have never been of much interest to me. I can only give you the address of someone who is an expert in the area of the development of logical thinking: Dr. Leslie Smith, Dept. of Education, University of Lancaster, LA1 4YL UK.

I'm sorry that I cannot do more for you,

Best wishes,

Ernst von Glasersfeld



From: Liu Chaochun <liuchaoc@comp.nus.edu.sg
Subject: Some doubts

Dear Professor:
I am a graduate student and has learned constructism for some time. I  really think RC is a marvelous theory and it has changed my thinking in  some way. However, I have some doubts.

1: I largely accept that knowledge is constructed and not truthful representation of reality, as you said, there are many viable approaches to avoid constraints. However, I don't like the word "adaptive", or the biological and passive flavor of RC in large. RC seems saying we construct and modify knowledge to adapt to experience, mainly to avoid a bad experience. I think RC misses an important point:human's purpose, goals and needs. Human actively construct knowledge to fulfill their purposes within the constraints of environment, not just passive adaption. Though Rc claim knowledge is relevant to goals, but obviously we can't say all knowledge is adaptive. In terms of goals and needs, we can identify several levels, and only the lowest level (physical needs) can be said as adaptive and for survival. Other higher level needs, like craving for arts, religion, science, can not. Take Einstein for example. His sustained passion, craving for science is not adaptive. Yes,RC claims there are two kinds of adaption, the second is on the conceptual level needed to build science knowledge, but this seems not reasonable. What force has asked for conceptual adaption? Most people have lived well with their practical, not so coherent and theoretical (comapred with scientific knowledge) knowledge.

2: RC is post-epistemological, and its sole reliance on subjective experience makes it hard to support itself and criticize its opponent. Foe example, I read from article of RC criticizing empiricism somewhat like "we can't get valid generalization from empirical data base on logic".But RC also is not based on logic. Or "Empirical study has shown that even percetion is an active construction process, so there is no empirical data in the sense of the empiricist, and this provide support for constructivism". Here empirical conclusion is used to support constructivism, and against empiricism. My point is on what grounds can RC support itself. Everyone knows we can't just cite personal experience to support our theory in scientific argumentation. This letter is long and I am quite sorry to say, it is also blunt. I hope you don't mind. I can see from your response to others that you are open minded and will not be bothered. I really respect you from my heart and my doubts are sincere. 
Liu Chaochun


Dear Liu Chaochun,

Thank you for articulating your doubts about RC and sharing them with me.I like this much better than people telling me they believe what I say, for they have to find out for themselves what may be right for them. I'll go through your statement and pick out the points where I think an explanation of my perspective may be helpful. RC seems saying we construct and modify knowledge to adapt to experience, mainly to avoid a bad experience. Human actively construct knowledge to fulfill their purposes within the constraints of environment, not just passive adaption. Though Rc claim knowledge is relevant to goals, but obviously we can't say all knowledge is adaptive.

- I have tried to make clear that on the biological level it is a matter of survival (and thus of avoiding of fatal experiences), but on the conceptual level it's a matter of internal equilibrium, i,e., of avoiding incompatibilities and contradictions among concepts, relational notions, theories, goals, and ways of thinking in general. This division is fundamental in Piaget's and also in my model. And I have often repeated that the choice of goals is part of ethics, a domain in which rational thought (of which RC is a tentative model) has no decisive role to play. What force has asked for conceptual adaption? Most people have lived well with their practical, not so coherent and theoretical (compared with scientific knowledge) knowledge.

- Equilibration is certainly not a force. The assumption that there is a desire to approach and maintain it is one of the fundamental presuppositions of RC; like reflective consciousness and some form of memory. - Equilibration is also an internal affair and not very assessable by another person. Paragraph 2< - The expression: ''we can't get valid generalization from empirical data ...'' shows that you are still looking for some absolute TRUTH. The experiential reality of a constructivist is built on generalizations from empirical data and reflective abstractions from  these. I think you tend to interpret 'empirical' as referring to an  experience-independent reality. That's a mistake that many  writers (especially of psychology textbooks) have made. But empirical  means pertaining to experience. So there is no reason why RC should  disdain empirical data. But you are right: RC cannot be justified by  empirical data.
It's justification springs primarily from the incontrovertibility of the sceptics' doubt - we can never tell whether or not our picture of the world is 'really' like the world - and then from the strange fact that everybody believes to receive information through the senses, yet we have no plausible model of HOW such a transfer of 'information' could take place. Finally: don' t forget that RC does not claim to be 'true', it only hopes to be useful.

Best wishes,

Ernst von Glasersfeld


From: "Danielle Cross" <rpimath@hotmail.com
To: kenny@oikos.org

Dr. Glasersfeld:
Do you agree with the statement "Truth is Viability"?

Dear Ms Cross,
I think it is confusing to say that "truth is viability" and that is why I don't like the Pragmatists' statement: "truth is what works", although I agree with much of pragmatism. Even a constructivist needs a concept of 'truth', namely the adequate repetition of something experienced or abstracted from experience at some earlier moment. If I say: "I saw John at the cinema last night", it is a "true" statement if I actually did see him. If I didn't, it would be a lie. And this is a distinction that constructivists want to make as much as anyone else. As for the "Truth" philosophers used to speak of, namely "truth" as correspondence with some ontological reality, there is no room for it in the constructivist theory. Its place is taken by "viability" - but as this concerns exclusively the experiential world, it is in no sense equivalent to "truth". Best wishes,

Ernst von Glasersfeld


Dear Prof. Glasersfeld,

In your essay entitled 'The Perceptual Construction of Time' you write, "I believe, that the image of time moving and "going by" is misleading. What goes by are our experiences." This idea has always been very interesting to me.
I would go somewhat further and say that our conception of time is essentially an aspect of memory. The difference from memory in other animals is that humans have developed the ability to recall their memories without any stimulation from their sensory organs. We remember some experience or event, reflect on the memory in our heads, and then we extrapolate this ability in the notion of "time", "intelligence", "rationality" , etc. But memory can be rather simply explained as a process of mentally cataloguing different experiences into an ordered sequence.  I think other animals like dogs, for example, also experience memory. But where humans have developed the ability to reflect at will on their memory experiences (giving rise to the concept of time), dogs and other animals do not have the ability to reflect at will on their mental memory, or only very slighlty. For the most part, their recollection of events and experiences are only recalled when an event they have experienced in the past repeats itself through their senses. It's as if animals live for the most part in the present whereas humans have developed the mental capacity to remember the past and the futrure, ie. in "time".

I doubt a dog can reflect on the nature of fire while it is gnawing on a bone. But if you strike a match and hold it in front of the dog where it can see, smell and feel the heat, then it remembers. The process of "remembering could be efficiently achieved by an automatic mental process in which incoming sensual experiences are continually compared and analyzed against experiences stored in memory structures in the brain. The human brain had evolved the remarkable ability to recall and scan their experiences outside the context of their "real-time" senses.

My question is this: do you think the ability to recall past experiences and events (memory) and project these experiences into the future is merely another evolutionary adaptation that humans have acquired in a structure of their brain, and that this is the sole basis of human intelligence?

Thank you.

Mr. d'Apollonia,



Dear Mr. d'Apollonia,

My answer to the question at the end of your message is this: what we call "intelligence" is a multifaceted capability. It comprises reflecting, re-presenting, abstracting, comparing, projecting, associating, etc. In your 2nd paragraph you mention "the ability to recall memories without the stimulation from sensory organs." This is what I have called "spontaneous re-pre-sentation". I know of no evidence that animals have this ability. We can sometimes watch dogs dreaming, but I doubt that whatever re-presentations they are having are deliberate. And the deliberateness is crucial because it furnishes the basis of language, i,e, the semantic connection of symbols and re-presentations of past experiences. I do not agree with the statement that "our conception of time is essentially an aspect of memory." I think of memory as two-dimensional: on the one hand, it maintains the sequential order of experience (and your attention can follow that sequence backwards or forwards); on the other hand, your attention can move from any remembered point, following associational connections to other remembered items, irrespective of their position in the experiential sequence. The concept of time arise (in my view) when you project two experientially separate but associated events on to the whole experiential sequence of which they were part. The interval between them is then filled with a succession of other events -- and this makes it possible to think of "duration" and consequently of time.  I want to stress that this is the model I have developed for myself and that I also believe that no "explanatory" model we concoct can claim to be "true". Its value can spring only from its usefulness.

Best wishes,

Ernst von Glasersfeld



While investigating prolepsis (the human capacity for an intuitive- anticipation), I came across the program for a conference in 1998 on Computing Anticipatory Systems where you had given the keynote address. Please explain the primary relations between prolepsis and constructivism. I 've also read Lev Vygotsky's work referred to on the same topic. Are you aware of additional material on Vygotsky and prolepsis?                                       


Dear <gil@ats.org>

The prolepsis you are interested in is not the result of reasoning but of non-rational intuition. It lies outside the anticipation covered in my paper, which concerns the kind of anticipations based on inductive inferences from past experience. If you are interested in that paper, you can download it from: http://www.umass.edu/srri/vonGlasersfeld/publications.html  I'm sorry, I cannot help you with Vygotsky; I don't know whether he ever discussed your kind of prolepsis.

Best wishes,

Ernst von Glasersfeld





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