http://www.humanevol.com/doc/doc200303030400.html

The popular criterion presuppose the existence of the objective and solid fact as the generator of the doubtful subjetive experience. But the process is just the inverse, and their characteristics the opposed. The subjetive experience (I see a tree) provoke us the creation of one hypothesis (There is a tree). The subjetive experience is real, there are no doubt about it. However the objective hypothesis is fruit of a combination of imagination and perception, susceptible of error, and always subject to revision. The existence of the perception is a certainty. The existence of the perceived fact is a hypothesis.

As particular case of the previous thing, the existence of self is a certain subjective fact, of which there is no doubt. But its conceptualization as something external or by means of its relation with the rest of objects of the Universe produces a description of self that because objective is susceptible of error. That is, when one is observed itself, not when one establishes and puts test objective hypotheses about the nature of self as if it was an external object, but, simply, when one is observing itself, obtains a certainty of its observation.

But the subjective certainty difficultly can be explained with words. It does not make reference to the nature of concepts, or its relation to each other. What we obtain by means of the subjective experience is a existencial certainty, that it seems that only can be expressed in poetic forms, combinning words like: "God", "I", "Universe", "Everything", "Absolute", etc.

Without on approval clearing importance to the scientific method based on the creation and putting of objective hypotheses, probably indispensable for the survival --of self--, in this text stands out the habitual lack of conscience of the existence of the own subjective experience itself, probably also indispensable for the survival --of the essence of self- -.