The immune system and other cognitive systems

I t is becoming clear that the field of immunology is approaching a paradigm shift.It is agreed by most researchers that the immune system is a complex systemboth in its composition and its behavior. However, the most popular ideas of immune function treat the immune system in a mechanistic and reductionist man-ner. According to the clonal selection theory the immune system’s function is to defeat pathogens. The immune system identifies foreign antigens and destroys them. The identification of the foreign is made possible by removing, in the immune system’s prenatal development, all receptors that recognize self. Anything that an immune receptor identifies “must be the enemy ” [1]. Countering this mainstream view are a growing number of voices that state the need to change the clonal selection theory or discard it, claiming that such a simplistic appraisal of the im-mune system’s function and mode of action is untenable because, at the molecular level, we are closely related to the pathogens that invade us. There is a need to consider the immune system as a integrative system with the ability to see patterns and understand context [2,3]. It is in the context of this argument about the immune system that we present our theory of cognitive systems and claim that the immune system should be seen as such a cognitive system. The phrase “cognitive system ” is used in many fields to describe the various faculties that we and other organisms use to perceive and interact with the world. Despite its widespread use, the phrase “cognitive systems ” has not yet been defined in a way that can be applied to all of the cases in which it is used. We suggest the following criterion to differ between cognitive and noncognitive systems: In cognitive systems the perceptual sensitivities of the system are not preordained only by the plan of the system but need an interaction with their environment to define the system’s exact sensitivities.