In constructivism the subject, driven by his own interests, builds actively his own concept of reality through a process of integration of multiple perspectives offered.
Constructivism regains some concepts of positivism and neo-positivism: knowledge as an active construction of the subject, is present in most research.
Learning is not seen only as a personal activity, but as the result of a collective dimension of interpretation of reality. New knowledge is built not only and especially on the basis of what has been gained in past experiences, but also through sharing and negotiation of meanings expressed by a "community of actors".
Constructivism so defined, for various changes on the cultural, philosophical level and on technological research, originated as a new theoretical framework in the 70s and 80s. It stems from the collapse of the idea that knowledge can be objectively learned.
It arises primarily as a need of abandoning cognitive HIP (Human Information Processing) that has never completely given up some of its mechanistic components of behaviorism.
The main concepts which characterize the present constructivism are the following:
1) knowledge is the product of an active construction of the subject,
2) knowledge has character "located", anchored in the concrete context,
3) knowledge takes place through particular forms of collaboration and social negotiation
In the foreground is placed the "construction of meaning" emphasizing the activity character not predictable of such an activity.
Therefore, the theory of knowledge (epistemology) of constructivists postulates that knowing be the product of an active construction by the subject, closely connected to the concrete situation in which learning takes place rising from the social collaboration and interpersonal communication.
The philosopher and cybernetic Ernst von Glasersfeld in speaking of constructivism and its philosophical reflections asserts that human knowledge continuing a "true" or "objective" representation of a world that already exists "in itself", has determined the history of Western philosophy from its beginning until today. Ensued ingenious attempts to solve a paradox, namely that to prove a certain "truth" it would be necessary to compare all knowledge with that part of the reality that it is supposed to represent; but to make this comparison, it should have access to the reality as it was before going through the operations of the subject observer. In other words, such a proof of authenticity would require a comparison between one thing that is known and another unknown.
Already the pre-Socratics, half a millennium before Christ, knew that insurmountable paradox and provided to the school of Pirrone material for the formulation of the main arguments that all the skeptics to follow have not ceased to repeat.
For this reason, the skepticism has always stressed the need to find an alternative theory of knowledge which should be based on the fact that
1) knowledge is not something passively received, but something that the thinking subject constructs actively;
2) the cognitive function is adaptive, useful to the organization of the world of experiences and not the discovery of ontological reality.
Usually, however, skeptics declared that the reliable and true knowledge is impossible: they have decided not to change the concept of knowing.
Paraphrasing Ernst von Glasersfeld: over the last twenty years or so, it has been recognized the influence that constructivism exercised on teaching methods aimed at encouraging the thinking subject to build, adapting on the base of experience. The cases in which this approach has been applied have given generally successful results attested by an extensive literature. But there was also an inevitable backlash, a reaction that has taken the name of constructionism arguing that the conception of language and society reflects things that have a life of their own and independent as well as the construction of individual minds. The taking of some correspondence remains a metaphysical fiction since no confirmation of that correspondence can be provided as part of experience. Constructivism is a theory of knowledge and concerns, not how much it could "exist", but just how much can be known rationally.