| Von Glasersfeld's answers - April 2003  |



Dear Professor Von Glasersfeld,

I am a master's student for Dr. Bednarz and Dr. Kieran at the Université du Québec à  Montréal. Lately, I started to read a lot on constructivism and I had some questions for you -I will try to be clear.

I have always heard that for a constructivist, there is no such thing as independant reality, because in the constructivists perspective we construct our own reality -which is our interpretation and is different for each human beings. To do that, we construct it from our experiences and our interpretations of thoses experiences.

For me, this meant that there was no ontological world independant of us - because such a thing was a non sense for a constructivist.

However, I think I was wrong because I read an answer you wrote in June 1997 and it says: «Whatever may lie beyond experience is inaccessible to human reason. But this is no denial of ontological reality;...» and you add in December of the same year: «Radical constructivism does not deny a world beyond our experiential interface, but it denies the possibility of knowing it.».

For me, and this is where I need your help, this states clearly that there is an independant reality, but we can't know it rationaly. Instead, it is our interpretation of it that we construct -and we can't say it represent it, we can only say that it seems viable in it.
So we construct, for ourselves, our interpretation of our reality that we live in -based on our experiences and the invariants and constants that we experience in that unknowable «real» world.

Am I completely out of place or does my interpretation of it seems compatible with yours? Thank you very much in advance for your time.

Jérôme Proulx
Étudiant à  la maîtrise en mathématiques


Dear Jérôme Proulx,

I think you have got what I intend. Only the mystics may have access to an external reality, but then they cannot comunicate about it in rational terms.
I am reluctant to say "There IS a reality", because I don 't know what "is" could mean outside the domain of my experience. Therefore I limit myself to saying that I do not deny it. Not denying does not imply existence, it is simply part of agnosticism.

Best wishes,
Ernst von Glasersfeld



Dear Dr. Glasersfeld,

In the book, Radical Constructivism A Way of Knowing and Learning you wrote, "It is cetainly not the case 'anything goes'. It is always possible that an ontic reality manifests itself by impeding some of our actions and thwarting some of our efforts. But even if this should be the case, this ontic reality would manifest itself only in failures of our acting and/or thinking, and we would have no way of describing it, except in terms of the actions and thoughts that turned out to be unsuccessful." (Page 118)

Aristotle defined the following, "To say of what is that is not or of what is not that it is, is falsehood; to say of what is that is and of what is not that is not, is truth" . It seems to me that a radical constructivist argues we cannot know "what is". However, it is not clear to me how they would reply to knowing, "what is not that it is not." For example, could a radical constructivist say (and be consistent with her or his explanation of knowing):

1. It is true there is not an living adult tyrannosurus rex in our living room.
2. It is true I cannot jump to the moon.

Thank you for your time.


Sam Hairston


Dear Mr. Hairston,

Aristotle believed that the capacity of knowing transcends the domain of experience and that we can discover what is and what is not in an ontological sense. In my view no ontic world is accessible and, because the meaning of our words is necessarily derived from and pertains to our experiential world, we cannot tell what "to be" and "to exist" could possibly  mean in an hypothetical space beyond the experiential interface.
As to "truth", for a constructivist it cannot have the meaning it is assumed to have in traditional philosophy, i.e. that something correctly represents or matches reality. Hence a statement about an item will be considered "true" if it replicates what was or will be said about the item in another experiential frame; or, as Ceccato said, if the operations that give rise to it now are the same that gave rise to it then. - Therefore, if you tell me that there is a tyrannosurus rex in your living room, I'll consider it a hallucination until I or someone else can conform its presence (hence the extraordinary effect of collective hallucinations such as crying madonnas and the like). Jumping to the moon is a bad example because given the right sort of rocketry you might pull it off.

Best wishes,

Ernst von Glasersfeld


Dear Mr. Glasersfeld,

I´m a student of philosophy from the University of Essen, Germany, writing an paper on the radical constructivist theory of knowledge. I would highly aprechiate information of the basic concepts of the radical constructivist (RC) approach to knowledge and their difference to actual contextualist approaches like those of Michael Williams, for example. I think context play an important Role in both of them, but what makes RC specifically different from such kinds of Knoeledge-Theories?

sincerly yours

Jörg Siefke-Bremkens


Dear Mr. Siefke-Bremkens,

I'm afraid I cannot answer your question because I do not know Williams' or other "contextualist" epistemologies. However, if the context they accentuate is assumed to be observer-independent, the theories will necessarily be incompatible with RC. - You would have to enlighten me as to how contextualists define knowledge and what, in their view, it represents.

Best wishes,

Ernst von Glasersfeld


Dear professor Von Glasersfeld,

Thank you very much for your reply (februari 2003) and the quoted passage in "Le structuralisme" of which you gave your interpretation earlier (in a december 2002-answer). Sorry to hear your books got lost in a fire.

I would like to answer your question with regard to '(non-)explanatory concepts', and put two questions to you related to the matter of Piaget being neither a realist nor an idealist.

You asked me to give some examples of «explanatory concepts» as opposed  to non-explanatory ones because it is not clear to you how to make that distinction.
I would like to refer to Peirce's notion of abduction; a concept that enters in a abductive inference in order to explain/understand a surprising phenomenon is an explanatory concept. So, an explanatory concept refers directly to a surprising phenomenon, and a non-explantory concept doesn't (neither directly nor indirectly). As an example, the notion of IQ is not induced by a surprising phenomenon (as far as I know), and all other psychometrically related 'concepts' I would say.

My first question to you is, acknowledging Piaget is neither a realist nor an idealist, whether you find Piaget is having a pragmatic-like epistemology?
The following passage in your 'Hommage to Jean Piaget' gave me food for this question:

"Adaptation is, in fact, a negative concept. It does not require any knowledge of what really exists - it merely implies that whatever is functionally successful will live and reproduce itself. It is the result of trial and the elimination of what does not work. The fact that an organism is 'adapted' only shows that it has found a way of coping with the world in which it lives (..)".

My second question is, agreeing one could interpret Piaget (slightly) differently i.e. before and after he modified ideas, is what you'ld make of the following passage in Le structuralisme p.35-36 (1970):

"Mais comprendre ou expliquer ne se borne nullement alors a appliquer nos operations au reel at a constater que celui-ci se «laisse faire»: une simple application demeure interieure au niveau des lois. Pour depasser er atteindre les cause, il faut plus: il est necessaire d'attribuer ces operations aux objects comme tels et de les concevoir comme constituant en eux-memes des operateurs. C'est alors, et alors seulement, que l'on peut parler de «structure» causale, cette structure etant le systeme objectif des operateurs en leurs interactions effectives."

I hope you have the opportunity to reply.

Yours sincerely,

Jenny McDermot


Dear Ms. McDermot,

Thanks for the examples of explanatory and non-explanatory concepts. I agree about IQ. It explains nothing. It merely designates what is measured by tests that are called "intelligence tests" but do not reliably measure intelligence. IQ is therefore a pretty useless concept; unlike, say kilometer, which is not an explanatory concept either but a useful one.  The matter of abduction is, I think, a little more complicated. Peirce explained that a "surprising" event can be turned into an expectable one by the invention of a rule. I am reluctant to call the rule a concept. I would reserve this word for the items that the rule concatenates in such a way that  the surprising event becomes its normal outcome.

With regard to your two questions about Piaget, let me first say this: As a constructivist I cannot discriminate between my interpretation of Piaget and what he "really" was. I can only try to adjust my interpretations so as to obtain the most coherent, consistent position. My constructivism has indeed parallels to pragmatism, but I have tried to focus on the analysis of the  constructs that "work" (are viable) and on showing (which the pragmatists did not) that we can have our experiential reality without reference to an ontological one.

I have no difficuly agreeing with what Piaget says there. If we want causal explanations of phenomena, we have to reify our experiences and treat them as independently related and acting upon each other. This is part of our  construction of reality.

Best wishes,

Ernst von Glasersfeld


Dear Professor von Glasersfeld,
I admire your work and would like to learn more about it. Is there any way we can access your " An exposition of constructivism: Why some like it radical" on the Web.

Thank you very much in advance for your time and generosity.

Omar Villarreal
Universidad Tecnológica Nacional
College of Education - INSPT
Buenos Aires - Argentina


Dear Mr. Villarreal,

Thank for your interest in my work. I am sending you below a copy of the paper you requested .

Best wishes,

Ernst von Glasersfeld

An Exposition of Constructivism: Why Some Like it Radical



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