Internal Senses

Unlike other organs that operate continuously, such as the heart and kidneys, many of the operations of the nervous system shut down during sleep. The evolutionarily conserved unconscious state of sleep that puts animals at risk from predators indicates that it is an indispensable integral part of systems operation. A reasonable expectation is that any hypothesis for the mechanism of the nervous system functions should be able to provide an explanation for sleep. In this regard, the semblance hypothesis is examined. Postsynaptic membranes are continuously being depolarized by the quantally-released neurotransmitter molecules arriving from their presynaptic terminals. In this context, an incidental lateral activation of the postsynaptic membrane is expected to induce a semblance (cellular hallucination of arrival of activity from its presynaptic terminal, which forms a unit for internal sensation) of the arrival of activity from its presynaptic terminal as a systems property. This restricts induction of semblance to a context of a very high ratio of the duration of the default state of neurotransmitter-induced postsynaptic depolarization to the total duration of incidental lateral activations of the postsynaptic membrane. This requirement spans within a time-bin of a few sleep-wake cycles. Since the duration of quantal release remains maximized, the above requirement can be achieved only by ceiling the total duration of incidental lateral activations of the postsynaptic membrane, which necessitates a state of sleep.

Avicenna and Thomas Aquinas understand animal intelligence in reference to the activity of vis aestimativa, through which they explain animal behaviour as being consequent to an apprehensive appraisal of its environment. This apraisal must be distinguished from the representative knowledge of the phantasma, because it is not of per se sensed qualities, but per accidens, that Avicenna calls intentiones. Explaining animal behaviour from the vis aestimativa allows to understand it without attributing it to intelligence, which has been classically considered to be exclusive of rational beings’ conceptual knowledge of reality.

La teorización acerca de la facultad estimativa se encuentra en los comentarios árabes de los textos aristotélicos, aunque aparece en comentadores anteriores, de forma más difusa. Tomás de Aquino incorpora, con ciertos matices, la explicación de Averroes acerca delos sentidos internos, en los cuales se incluye esta facultad. El Aquinate utiliza términos distintos para referirse a esta facultad:cogitativa, cuando se refiere a esta facultad en el hombre y estimativa, cuando se refiere a esta facultad en el resto de animales.La razón de esta distinción terminológica es que en el hombre, el ejercicio de esta facultad recibe influencia de la facultad intelectiva;en el resto de animales, en cambio, se guía por el instinto.La facultad estimativa es aquella mediante la cual valoramos la realidad particularmente. Es esencial para la supervivencia animal ya que por ella el animal juzga lo conveniente y lo nocivo. En el hombre, es antesala del conocimiento racional y, a la vez, detonante de las emociones. Fruto del ejercicio de la cogitativa se genera una memoria de juicios valorativos particulares que, conjuntamente con la actividad intelectiva, encauzan la valoración particular por la que nos regimos en nuestro quehacer diario.La conceptualización de la facultad estimativa tiene una génesis un tanto confusa, pero la explicación tomista permite argumentar filosóficamente la distinción cualitativa que existe entre el conocimiento animal y el humano y, además, explicar ordenadamente los entresijos de la vida mental.