Definition anchored in philosophy (Scholastic)

The current definition of virtual comes from the Scolastique of the Middle Ages. It is in particular with this tradition, that Gilles Deleuze and Pierre Levy refers when they speak about virtual.

As virtual a being or a thing is described not having a current existence (i.e. in the tangible facts), but only one existence in imagination. Virtual is thus taken within the meaning of “possible”, of a suitable potential state for actualization .

Example at Pierre Levy: “Why the consumption of information isn't destructive and its detention it is not exclusive? Because information is virtual. ”

This word became very with the mode since the explosion of the techniques Informatique S opening of the almost infinite possibilities of Communication in network on a world scale , without physical contact between the people thus comparison. At Pierre Levy for example, the virtualisation of reality takes place by a reinforcement of the potentialities of the given .

It is important consequently to note that the virtual one is not opposed to the real but to current (what exists in the concrete one), whereas reality is opposed as for him to the Possible.

The possible one is already definite, given, it is a latent reality to which it misses only the realization. To take again a regularly quoted example, the tree is virtually present in seed. The virtual one is what exists in power and not, indeed, in a concrete way but acts by actualization. Thus the virtual one is distinguished from possible in what it is not predetermined and, consequently, unforeseeable, answering a multiplicity of parameters. The virtual one is not unreal in measurement or reality is not summarized with what is concrete or material, it is recipient of reality.

Definition anchored in the technical etymology (virtus) and employment

Is virtual what, without being real has, with force and in a fully current way (i.e. nonpotential) qualities (properties, qualia) of reality. (Denis Berthier)

This definition is based on the etymology (of Latin virtus - virtue, and not of " virtualis" , word invented with the Middle Ages), like on the technical uses of the term in expressions as virtual image , virtual reality , " environment virtuel" , etc

The prototype of virtual in this direction is the reflection in a mirror. Indeed, the reflection of an object is already there, that I would be there or not to perceive it; it is not on standby of any actualization.

In this design, one understands that of a virtual object, nonreal but fully current, can be resulting from the real effects (like the considered rays), so that perception that one has some and all our relation with him are quite real, just like are to it (in the field of vision) that of the reflection or (in the auditive field) that of a virtual sound. One includes/understands thus that one can resort to virtual reality to look after phobias.

The significant importance of this definition is the fact that it lays the stress on the virtual one like real and current experiment but mediatized by an interface, a technical object.