Understanding the Digital Age

A Dialogue with Rafael Capurro

by Linda Treude


Contribution to Maria Eunice Quilici Gonzalez and João Antonio de Moraes (eds.): Life, Information, and New Technologies. 2015 (forthcoming). The text is a revised and enlarged translation of: Information, Zeichen, Kompetenz. Ein Interview mit Rafael Capurro zu aktuellen und grundsätzlichen Fragen der Informationswissenschaft. In Information. Wissenschaft und Praxis, 62 (2011) 1, 37-42.


The term information is omnipresent in academic research as well as in everyday life. Buzz words such as information society, information age or information overload are floating around everywhere. But what do we mean exactly with 'information' in different contexts?

The philosopher Rafael Capurro dealt with this question in the late 1970's in his PhD thesis on the concept of information. [1] Especially the philosophical community was suffering at that time from a lack of reflection thereupon. Capurro tried to fill this gap. The following remark by the physicist and philosopher Carl Friedrich von Weizsäcker (1912-2007) had a particular impact on him.

"Today we are getting accustomed [...] to understand information as something different from matter and consciousness. What we have discovered is an old truth in a new place. It is the Platonic eidos, the Aristotelian form, expressed in words such that also a human being in the 20th century can learn about them." [2]

Weizsäcker’s step back to the history of ideas motivated Capurro also to deal with ethical issues of the information society particularly since the rise of the internet. The handling of digital information requires new cultural skills that are addressed with the term 'information literacy.' In the last ten years many projects in the Library and Information Science field (LIS) include or are even focused on information literacy (IL). In many of these projects there is a pre-understanding that IL has to do with the ability to find, filter, and process digital information. At the same time, there is a gap between this pre-understanding and the ongoing academic discussion on the concept of information. The following dialogue deals particularly with this gap.

What makes information a challenge in the age of the World Wide Web? According to Vilém Flusser (1920-1991), today it seems to be more important to generate “pure information“ than “informed objects".[3] Do you agree?

If Flusser's “pure information" means the production of digital artifacts [4]
we are facing the opposite problem today, namely the rise of the so-called Internet of Things.[5] The cyberspace is not separated or independent from the physical world as John Perry Barlow suggested 1996 in Davos. Quite the contrary, it is present in all areas of life. We live in digitally 'in-formed' societies. But the ability to deal with a growing information overload differs tremendously with regard to less 'in-formed' societies.[6] We've been discussing for years the digital divide as that which deals with the lack of access to digital information.[7] This divide persists still  between countries with nationwide coverage of internet access and those with lesser or no access. This gap is also relevant within so-called information rich societies. Moreover, the divide is not just technical but also cultural, educational and political. The internet is subject to censorship in many countries and can be used and, in fact, is being used as an instrument for surveillance and social control. At the same time, it offers new possibilities for a better life as well as for social change.[8]

Information literacy is considered a key issue in many LIS projects. What do you think about it and which skills belong to it?

If the concept of information literacy or, better, "information literacies" (Limberg et al.), is not reduced to written information but includes the ability to deal with all forms of digitalized information as well as learning how to handle digital codes and devices, then it should play a key role in the educational sector.
[9] But it would be pedagogically misleading to understand information literacies as dealing only with skills without learning also a critical appraisal of possible misuses. Responsible practices with regard to blogs, apps, e-mails or social software should be taught in schools no less than the creative use of the web for learning processes and political participation. Democracy has to do more and more with interactive digital processes. Information literacies are required in all areas of society but each area has its own standards, risks and objectives. In a globalized world, information literacies deal with learning how, why, how far and to whom we reveal or conceal who we are in a digital environment with regard to specific situations and cultural traditions.[10]

According to the philosopher Hans Blumenberg (1920-1996) in his "The Legibility of the World" ("Die Lesbarkeit der Welt" Frankfurt 1979) the book is a foundational metaphor. How do you see the relationship between information literacy and textual interpretation today?

In his essay "The Mission of the Librarian", the Spanish philosopher José Ortega y Gasset (1883-1959) wrote:

“[the] democratic society is a daughter of the book, it is the triumph of the book written by man over the book revealed by God and over the book of laws dictated by autocracy."[11]

In the meantime, democracy is changing under the impact of interactive digital media as paradigmatically opposed to the hierarchical one-to-many structure of mass media. But both paradigms are more and more intertwined as mass media include interactive devices and the internet is shaped by monopolies such as Google, Facebook, Twitter or Amazon. The right to internet access has become  de facto a human right similar to freedom of speech and freedom of the press.[12]  This issue  was controversially discussed at the World Summit on the Information Society ten years ago. The world is not only readable, as Blumenberg's metaphor suggests, but also writable. In both cases it is today digitally and socially interactively 'in-formed'. We want to be informed as well as to inform others using digital media. The foundational metaphor of our age is not any more the book but the digital interface.[13]

The rising frequency of the occurrence of the term 'information literacy' is correlative to the development of the World Wide Web or digital media- and communication technology in general. The medium or the form seems to influence the content. What do you think in this context about McLuhan's aphorism „the medium is the message“?

The dualism between content and medium is not feasible. It was criticized already by Plato in the dialogue "Phaidros," the first media critique in the Western tradition. Plato's paradoxical devaluation of writing with regard to spoken language (logos) shows that no media is neutral concerning the content it is supposed to transmit as well as between the relationship between sender and receiver. Writings are not able to defend themselves from the misunderstanding of the readers because their 'father' or author is absent. This is one of the critical arguments given by the pharaoh to the inventor of writing, the Egyptian god Theut, who corresponds to the Greek god Hermes. Plato points out the advantages of the lively dialog face-to-face where the philosopher as educator takes care dynamically of the personal level of learners, mostly Athenian male citizens.[14] The French philosopher Jacques Derrida (1930-2004) criticized this understanding of writing as being "logocentric." [15] Spoken language has not the same quality and effect as written language. Each medium enables not only different ways of dissemination but also different kinds of interpretations.

McLuhan's (1911-1980) aphorism “the medium is the message" [16] is related to the difference between “hot” and “cool” media, i.e., to the work of the recipient to understand a message. McLuhan was not only a media theorist but also a message theorist. His theory of media can be interpreted as a message theory that I call 'angeletics' (Greek angelia = message).[17] A medium can be understood as in-between a sender and a recipient embracing both of them, but it can also be understood as a tool. In both cases it has to do with the issue of a sender offering a message or what the German sociologist Niklas Luhmann calls a "meaning offer"  ("Mitteilung" or "Sinnangebot"). The recipient chooses a possible meaning which is the information ("Information"). Such information is integrated into the recipient's (pre-)understanding ("Verstehen"). [18] Luhmann's theory of communication is one of the most ambitious and influential contemporary theories of communication.

In my thesis [19] I examined various dimensions of the concept of information as a foundation for information literacy. According to the so-called "Capurro's trilemma" it is impossible to formulate a unified theory of information. What do you think about such attempts to unification?

The question we must ask first is: 'what does "unified" mean?' And then: 'who needs such a unified concept?' The meaning of a word in everyday life does not need to correspond to or to be "unified" with its use within a scientific theory and vice versa. A precise definition within a theory remains often related to its use in natural language as John Austin once remarked:

"[...]a word never well, hardly ever shakes off its etymology and its formation. In spite of all changes in and extensions of and additions to its meanings, and indeed rather pervading and governing these, there will still persist the old idea." [20]

There is a circle between natural language with its plasticity of meanings –the American philosopher Hilary Putnam calls it the "porosity" of language–,[21] and the interest of sciences to define their concepts making them as univocal or informational as possible. This relationship between the plurivocity of language and the univocity of information can be a productive or hermeneutical one as analyzed by Weizsäcker in the paper I already mentioned as well as by Hans-Georg Gadamer (1900-2002), the founder of philosophical hermeneutics in the tradition of Martin Heidegger's (1889-1976) existential analysis.

The so-called imprecision or fuzziness and the changes of word meanings in daily life offer the possibility for science to redefine freely a concept within a theory. Claude Shannon, for instance, developed a concept of information arising but also partly opposed to its everyday meaning as Warren Weaver remarked.[22] Other sciences, including information science, are not happy to deal alone or mainly with Shannon's concept because the semantic and pragmatic dimensions are excluded. Since Shannon, plenty of information concepts have been developed, which partly overlap and are even equivocal. Peter Fleissner and Wolfgang Hofkirchner called this issue “Capurro’s  trilemma." [23] I formulate it as follows:

"Information may mean the same at all levels (univocity), or something similar (analogy), or something different (equivocity). In the first case we lose all qualitative differences, as for instance when we say that e-mail and cell reproduction are the same kind of information process. Not only the "stuff" and the structure but also the processes in cells and computer devices are rather different from each other. If we say the concept of information is being used analogically, then we have to state what the "original" meaning is. If it is the concept of information at the human level, then we are confronted with anthropomorphisms if we use it at a non-human level. We would say that "in some way" atoms "talk" to each other, etc. Finally there is equivocity, which means that information in physics and information in education are wholly different concepts. In this case, information cannot be a unifying concept any more, i.e. it cannot be the basis for the new paradigm you are looking for." [24]

This trilemma goes back to the Aristotelian distinction between univocal, equivocal and analogous terms. Aristotle started his research with the question: 'Which are the different meanings and uses of a concept and how are they related?' The most philosophical crucial analysis dealt with the different meanings of the concept of being ("to ón légetai pollachós," "being can be understood in different ways").

The trilemma can be solved by taking a certain definition and its context as the first and original one, this meaning being called the primum analogatum. All the other applications and definitions have to be compared to this first and 'true' one. This solution is proposed, for instance, by the German philosopher Peter Janich for whom the concept of information belongs originally to the human context, analogical applications having only a limited and mostly misleading legitimation. [25]  Another way of solving the trilemma, which I prefer, consists in accepting the coexistence of different concepts in different sciences and contexts building a network of "family resemblances" or "language games" (Wittgenstein). [26]

The philosopher and polymath Charles Sanders Peirce (1839-1914) was the founder of modern semiotics and pragmatism. He proposed to transform logic into a theory of signs and to follow a functional or pragmatic interpretation when ideas or concepts are difficult or unclear. Do you believe that Peirce's 'pragmatic maxim' is a possible solution of the trilemma?

Yes, as far as the Peircean 'interpretant' makes possible a change from one context to another. This can take place also within a science. Information science, for instance, can define information as dealing with the meaning of a message. The interpretant can be the producer, the mediator or the recipient. At the document-level, however, information means an object bearing that message. The concept of information differs according to specific theoretical and/or practical areas. These differences can be analyzed from a hermeneutical perspective. [27] Peirce writes:

“Consider what effects, that might conceivably have practical bearings, we conceive the object of our conception to have. Then, our conception of these effects is the whole of our conception of the object." [28]

This means that the triadic relation –our conception, the effects, the object–, defines an area of research or practice or a regional ontology as it is called, for instance, in Husserl's phenomenology. But Peirce goes beyond Husserl and comes near to Heidegger as far as it deals explicitly with the "practical bearings" excluding metaphysical objects. This links him also to Kant's and Heidegger's critique of metaphysics. But Kant's moral imperative is of another kind as Peircean pragmatism.

The so-called DIKW-model (Data-Information-Knowledge-Wisdom) [29] works on the basis of a hiearchy between these concepts. What is the relation between information and sign in this regard?

This hierarchy is problematic in many regards. It suggests that something somehow emerges from something else. You feed your mind or the computer with data and somehow information emerges. Knowledge also emerges somehow from information. Similarly it happens between knowledge and wisdom. This is, obviously, a caricature of a complex issue. Even philosophy is supposed to be a longing for wisdom and not wisdom itself. Those who call themselves 'wise' are either gods or charlatans. Scientific knowledge is limited and subject to criticism. The whole refers to different taxonomies of knowledge. In the Platonic and Aristotelian tradition there is a difference between opinion (doxa), practical knowledge (empeiria), know-how (techne), scientific knowledge (episteme), ethical knowledge (phronesis) and knowledge of the first principles (sophia). This taxonomy was changed and even turned upside down in modernity, for instance, by Kant and Peirce who rejected metaphysical knowledge. [30] According to Heidegger signs ("Zeichen") are "witnesses" ("Zeuge") of something to which they refer ("zeigen"). They are primarily within a practical holistic network of references ("Zeugganzheit") which makes the difference to a formal network of references ("Verweisungen") that are not necessarily signs in every instance and remain abstract. He writes:

"Among signs there are symptoms [Anzeichen] , warning signals, signs of things that have happened already [Rückzeichen] , signs to mark something, signs by which things are recognized ; these have different ways of indicating, regardless of what may be serving as such a sign. From such 'signs' we must distinguish traces, residues, commemorative monuments, documents, testimony, symbols, expressions, appearances, significations. These phenomena can easily be formalized because of their formal relational character; we find it especially tempting nowadays to take such a 'relation' as a clue for subjecting every entity to a kind of 'Interpretation' which always 'fits' because at bottom it says nothing, no more than the facile schema of content and form." [31]

Heidegger chooses the “adjustable red arrow” motor cars were fitted up with as an example for a special reference or indication. This sign is an “item of an equipment which is ready-to-hand to the driver in his concern with driving, and not for him alone"
as the showing of the sign stands (in this case) “in the whole equipment-context of vehicles and traffic regulations”. [32] To put it another way, there is no such thing as an isolated sign, because a sign always exists in "everyday care" ("alltägliches Besorgen") within an "equipmental totality" ("Zeugganzheit"). Signs are merely "present-at-hand" ("vorhanden") when detached from their practical care-relations. “World” in Heidegger's sense is constituted by this kind of care-relations of meaning and reference. The communication of such meanings, i.e., information, is possible and meaningful only within the background of a common world of practical networked references.

Here we should raise the question: what is this “common world” and who is defining it, i.e., who has the power to exclude or to integrate? When Heidegger defines signs as ready-to-hand he puts all the emphasis on the usage and serviceability, whereas a sign in Peirce is about meaning in the broadest and most basic sense. In semiotics the concept of sign is not only defined by relations, but also by the process of interpretation. Peirce calls this semiosis. Is it possible to understand information as process, accordingly?

It is important not to absolutize the concept of sign following the "temptation", as Heidegger warns, to take such a relation between things "as a clue for subjecting every entity to a kind of 'Interpretation' which always 'fits' because at bottom it says nothing, no more than the facile schema of content and form." This leads eventually to a metaphysical semiotics where everything is understood only as a sign. We are, as Octavio Paz wrote, “grammarian monkeys,” i.e., we have indeed the possibility to see everything that we encounter as a sign, but “[...]trees are not signs: they are trees." [33]
When we perceive trees as signs, thanks to our “grammatical” condition, and we name them whereby, we make sense, and we share this sense and communicate it to other “grammarian monkeys." We inform them. This means also that we always have only a particular view on things within the context or the “world” making it possible to interpret trees as "something standing for". The key issue is not to identify this 'as' with an 'is' or to be aware that each time that we speak about 'is' we have to do with an 'as.' To interpret everything 'as' a sign does not mean that everything 'is' indeed just a sign. In this case we would fix the meaning of being and instead of understanding semiotics as (!) a possible interpretation of the world and ourselves, we would state that this 'is' indeed the case. To be means then to be a sign. It is the indeterminacy of being that allows us such a fixation. [34] The semiotic view of the world as a possible interpretation of being makes manifest the fragility of the human interpretant in her aim to make herself the world fully understandable. This is only possible from the perspective of a transcendent or metaphysical observer beyond the space-time limits of human existence. For such an observer there is no need for information whatsoever as it 'in-forms' everything.

In his book "Cybersemiotics. Why Information Is Not Enough" (Toronto 2008) Søren Brier proposes a holistic approach to information based on empirical studies of cognition and communication. Does your rejection of a unified and universal concept of information imply the impossibility of such a universal information science?

We can study cognition and communication empirically based on such a „cybersemiotic“ theory of information, as Brier proposes following Peircean ideas which are quite similar to Luhmann's approach on meaning-generating systems. All the great systematical philosophies, e.g., of Aristotle, Thomas Aquinas or Hegel, aimed at something like this. Heidegger called those endeavours to grasp and fix the meaning of being metaphysics. Kant thought it impossible for us not to ask such metaphysical questions. But at the same time he warned us to be aware about the limits of pure reason when trying to answer such questions.

What are the future tasks and challenges for information science?

I think that information science has to increase its awareness towards social questions and free itself from its one-sided focus on information retrieval technology. Joining the library science tradition(s) it should investigate social phenomena, dealing with the production, preservation, analysis, transmission and use of all kinds of knowledge according to a classical definition.[35] Although information science, from this perspective, belongs to the humanities and social sciences, it does not imply giving up the methodology of computer science or of the natural sciences when analyzing the phenomena at stake. But it does mean keeping in mind its main goal, namely to contribute to a critical view of information literacies within the background of societal needs and cultural traditions in a digitally globalized world.


Linda Treude thanks Sascha Freyberg for philosophical support. Rafael Capurro thanks Linda Treude for her questions and the English translation. A special thanks goes to Jared Bielby (University of Alberta, Canada) for critical remarks, bibliographic references and for polishing the English.


[1] Capurro, Rafael: Information. Ein Beitrag zur etymologischen und ideengeschichtlichen Begründung des Informationsbegriffs. [Information. A contribution to an etymological and conceptual-historical foundation of the concept of information] Munich 1978.l

[2] "Man beginnt sich [...] heute daran zu gewöhnen, daß Information als eine dritte, von Materie und Bewußtsein verschiedene Sache aufgefaßt werden muß. Was man aber damit entdeckt hat, ist eine alte Wahrheit in einem neuen Ort. Es ist das platonische Eidos, die aristotelische Form, so eingekleidet, daß auch ein Mensch des 20. Jahrhunderts etwas von ihnen ahnen lernt.“ (transl. R. Capurro)  In Carl Friedrich von Weizsäcker: Sprache als Information. In: Die Einheit der Natur, Munich 1974, p. 51 (Engl. transl. The Unity of Nature, New York 1980). The talk was held in Munich in 1959 at the conference "Die Sprache" ["Language"] organized by the Bavarian Academy of Fine Arts.

Vilém Flusser: Die Informationsgesellschaft. Phantom oder Realität? Cologne 1996.

On Flusser's ideas of "pure information" and "information objects" see V. Flusser: Towards a Philosophy of Photography (1984) (or. German ed. Für eine Philosophie der Fotografie, Göttingen 1983). I quote: "In the case of such advanced images [electromagnetic photographs, RC] the material basis of information has completely disappeared and electromagnetic photographs can be created artificially at will and processed by the receiver as pure information (i.e. the 'pure information society')".

See Hektor Haarkötter and Felix Weil (Guest Editors): Ethics for the Internet of Things. In International Review of Information Ethics, 22 (2015) (forthcoming).

[6] On information overload see my: Between Trust and Anxiety. On the Moods of Information Society. In Richard Keeble (ed.): Communication Ethics Today. Leicester 2005, pp. 187-196. See also my: Medicine 2.0. Reflections on a pathology of the information society. In: Innovation, journal of appropriate librarianship and information work in Southern Africa, Number 46 (2013) (Special Issue: Information Ethics, ed. Stephen Mutula) pp. 75-96.

[7] Rupert Scheule; Rafael Capurro and Thomas Hausmanninger (eds.): Vernetzt gespalten. Der Digital Divide in ethischer Perspektive. Munich 2004.

[8] See the special issue of the International Review of Information Ethics (IRIE) on "New ICT and Social Media: Revolution, Counter-Revolution and Social Change" (Guest Editors:  Christopher Coenen, Wolfgang Hofkirchner and José María Díaz Nafría), December 2012.

[9] I borrow the plural form "information literacies" from Louise Limberg, Olof Sundin, Sanna Talja: Three Theoretical Perspectives on Information Literacy. In Human IT, 11 (2012) 2, pp. 93-130. I quote: "Three theoretical perspectives are presented that represent different understandings of information literacy; phenomenography, sociocultural theory and Foucauldian discurse analysis. According to all three theoretical lenses, information literacy is embedded in and shaped by as well as shaping the context in which it is embedded. In consequence, we propose the notion of information literacies in the plural." (p. 93). See also: Tadashi Takenouchi: A Consideration on the Concept of Information Literacy. In: International Review of Information Ethics, 2 (2004) 11. I quote: "Is information literacy "necessary for all"? Now we can answer this question in the following manner: It is impossible to conclude such without specifying the category, field, and level of the concept of information literacy in each situation. If we do not care about such matters, discussions will be confused and may lead to faulty conclusions." (p. 5); Christine Pawley: Information Literacy: A Contradictory Coupling. In: The Library Quarterly, 73 (2003) 4, pp. 422-452.

[10] See Rafael Capurro, Michael Eldred and Daniel Nagel: Digital Whoness: Identity, Privacy and Freedom in the Cyberworld. Frankfurt 2013. Abridged version in Johannes Buchmann (ed.): Internet Privacy, Berlin: 2012, pp. 63-142.

[11] José Ortega y Gasset: Misión del bibliotecario. Madrid 1962, p. 33: “La sociedad democrática es hija del libro, es el triunfo del libro escrito por el hombre escritor sobre el libro revelado por Dios y sobre el libro de las leyes dictadas por la autocracia.“ (Engl. transl. R. Capurro).

[12] See the overview in the ICIE (International Center for Information Ethics).

[13] Ivan Illich: In the Vineyard of the Text. A commentary to Hugh's "Didascalion". Chicago 1993.

[14] On the relation between the digital interface and the (Levinasian) 'face-to-face' see my: Face-to-face oder Interface? Möglichkeiten der Beratung per Internet. In Eric Mührel (ed.): Ethik und Menschenbild der Sozialen Arbeit, Essen 2003, pp. 107-118.

[15] Jacques Derrida: De la gramatologie. Paris 1967.

[16] Marshall McLuhan: Understanding Media: The Extensions of Man. New York 1964

[17] Rafael Capurro and John Holgate (eds.): Messages and Messengers. Angeleltics as an Approach to the Phenomenology of Communication. Munich 2011.

[18] Niklas Luhmann: Soziale Systeme. Frankfurt 1987.

[19] Linda Treude:  Das Konzept Informationskompetenz. Ein Beitrag zur theoretischen und praxisbezogenen Begriffsklärung. [The Concept of Information Literacy. A contribution to the theoretical and practical conceptual analysis]. Berlin 2011.

[20] John Austin: A Plea for Excuses. In Proceedings of the Aristotelian Society, 1956-57.

[21] Hilary Putnam: Representation and Reality. Cambridge 1988.

[22] See Claude Shannon: A Mathematical Theory of Communication. Bell Systems Technical Journal 27 (1948), pp. 379-423, 623-656 as well as Claude Shannon and Warren Weaver: The mathematical theory of communication. Urbana, IL 1949/1972.

[23] See  P. Fleissner, W. Hofkirchner: In-formatio revisited, Wider dem dinglichen Informationsbegriff. In: Informatik Forum 3/1995, 126-131.

[24] Rafael Capurro, Peter Fleissner, Wolfgang Hofkirchner: Is a Unified Theory of Information Feasible? A trialogue. In:  Wolfgang Hofkirchner (ed.): The Quest for a Unified Theory of Information. Proceedings of the Second International Conference on the Foundations of Information Science. Amsterdam 1999, p. 9.

[25] Peter Janich: Informationsbegriff und methodisch-kulturalistische Philosophie. In Ethik und Sozialwissenschaften 9 (1998) 2, pp. 169-182. See my criticisms: "Das Capurosche Trilemma" In ibid. pp. 188-189.

[26] See Rafael Capurro and Birger Hjørland: The Concept of Information. In Annual Review of Information Science and Technology Ed. B. Cronin, 37 (2003), pp. 343-411

[27] See my Hermeneutik der Fachinformation [Hermeneutics of Scientific Information]. Munich 1986, pp. 61-67 where I analyze Norbert Henrichs' semiotic view of information science. See also my Digital Hermeneutics: An Outline. In AI & Society 35 (2010) 2, pp. 35-42.

[28] Charles S. Peirce: How to make our ideas clear. In: Popular Science Monthly, 12 (1), 1878, pp. 286-302 (CP 5.388 – 410)

[29] Russell L. Ackoff : From Data to Wisdom. In: Journal of Applied Systems Analysis, 16 (1989), 3-9.

[30] See my Skeptical Knowledge Management. In Hans-Christoph Hobohm (ed.): Knowledge Management. Libraries and Librarians Taking Up the Challenge. IFLA Publ. 108, Munich 2004, pp. 47-57.

[31] Marrtin Heidegger: Being and Time. Oxford 1962 (transl. J. Macquarrie & E. Robinson), p. 108.

[32] Martin Heidegger, op.cit. p. 109.

[33] Octavio Paz: El mono gramático, Barcelona 1974, p. 97

[34] See my Towards an Ontological Foundation of Information Ethics. In Ethics and Information Technology 8 (2006) 4, pp. 175-186.

[35] See e.g. Harald Borko: Information science: What is it? In American Documentation, 19 (1968) 1.

Last update: October 16, 2014


Copyright © 2014 by Rafael Capurro, all rights reserved. This text may be used and shared in accordance with the fair-use provisions of U.S. and international copyright law, and it may be archived and redistributed in electronic form, provided that the author is notified and no fee is charged for access. Archiving, redistribution, or republication of this text on other terms, in any medium, requires the consent of the author.

Back to Digital Library
Homepage Research Activities
Publications Teaching Video/Audio