Constructivism is a theory of learning, which claims that students construct knowledge rather than merely receive and store knowledge transmitted by the teacher. Constructivism has been extremely influential in science and mathematics education, but much less so in computer science education (CSE). This paper surveys constructivism in the context of CSE, and shows how the theory can supply a theoretical basis for debating issues and evaluating proposals. An analysis of constructivism in computer science education leads to two claims: (a) students do not have an effective model of a computer, and (b) computers form an accessible ontological reality. The conclusions from these claims are that: (a) models must be explicitly taught, (b) models must be taught before abstractions, and (c) the seductive reality of the computer must not be allowed to supplant construction of models.

Key words: computer science education, dominant theory, idiosyncratic version, accessible ontological reality, ective model, theoretical basis, seductive reality, store knowledge, mathematics education

Excerpt: Constructivism is certainly the dominant theory, but it is being subjected to much criticism. Not that this is new for constructivism; it gained in support during the 1980s despite strong attacks and even political manœuvrings in its early days. In this chapter I will attempt to create the written equivalent of a snapshot. What can be seen in the picture is a scene at one instant. By the time the snapshot has been developed, when the book is published, the scene will look different, people and places will have moved on. Yet the snapshot will have captured something, although I do not pretend that the snapshot has captured any ‘truth’, however temporary. It is my fiction as I write it, and the reader’s fiction as it is read. It is a photo-journalist’s creation: the angle, the light, the subjects, all chosen to convey the effect the photo-journalist wishes to be seen, to carry that particular story.

Context: The dominant theory in immunology is straight neo-Darwinian, almost 60 years old and does not address its epigenetic foundation. In traditional immunology, cognitive notions are used only as metaphors: Cognitive notions derived from enaction (Varela) and biology of cognition (Maturana) may be applied to immunology. Problem: Why is there a huge gap between the rapidly growing knowledge in experimental immunology and applying this knowledge to medical issues? Could the difficulty be conceptual? Method: We review the history of Varela’s involvement in immunology to contribute to the genealogical and cartographic understanding of his work, and we highlight the key questions that still need to be addressed. Results: From our perspective, a phenomenon known as “oral tolerance” (stabilization of immune activity in relation to dietary and microbiota antigens) is crucial in the promotion of a change in paradigms. Applying non-metaphorical approaches to what is traditionally understood as immune cognition can be of great theoretical importance. For example, computer simulations of immunological activity were able to predict experimental results on oral tolerance. Reciprocally, experimental results, for example, the (adoptive) transfer of “oral tolerance” with mouse T lymphocytes, is critically important for immunological theory: “tolerance” understood as non-responsiveness cannot be transferred, thus it must be seen as an active phenomenon. Implications: The article emphasizes the importance of Varela (and his collaboration with Coutinho and Stewart, in Paris) for the development of immunological theory. Constructivist content: The organism, as a whole, is not a biochemical listing of properties, or the result of a genetic program but it is rather a process of continuous construction and maintenance.

Key words: Immunology, cognitive science, epistemology, Maturana, oral tolerance.