Descartes' Methodical Doubt: From Skepticism to 'Cogito, Ergo Sum'

Descartes' Methodical Doubt and the Foundation of Knowledge

Mental contents systematically subjected to methodical doubt will be:

1. The lessons learned.
2. The data of the senses (sometimes deceptive). This leads us to doubt the experience of the outside world. It even makes us doubt the existence of our own body, because we know it only through the senses.
3. Our experiences (as we say, anything other than the fruit of a dream). In many cases, it is impossible to distinguish waking from sleep, since the latter are presented to us as vividly as the experiences we have when awakened.
4. Our own thinking (and sometimes thoughts are also a source of deception, or perhaps an evil genius is deceiving me). The conception that has doubled in the period is free omnipotence, which makes us have a total uncertainty, because nothing assures me that God is not an evil genius whose purpose is that I am deceived. This makes us doubt even mathematics.

The conclusion reached after applying the method is that we found no mental content we can take for real. Skepticism seems to be the conclusion that we need to reach. However, to discard a first truth that there can be no question, even doubt: the existence of a self as subject of mental contents, "I think, therefore I am" first principle of philosophy.

The reasoning is discarding it: if the senses deceive me, if I am wrong for reasons or a god to me confused, it is clear that I am who errs and is deceived, and therefore I am something, I am. Thus, one can doubt everything except that we are something that doubt and that therefore it exists.

The cogito (thought) is self-evident, because it includes a thought and the subject who thinks.

Descartes, by doubting the correspondence between the mental world (ideas about things) and the external world (things), is moving away from the philosophy before him and begins a new way of understanding knowledge. The earlier philosophers, especially Aristotle, spoke of the knowledge of things of which they did not question its existence. Descartes refers to knowledge, things are different ideas about things and that things can not affirm its existence, but of my ideas together. It is the beginning of philosophical idealism.

By intuition, "I think, therefore I am" (cogito, ergo sum) we know that we exist, but still do not know what features we have, what kind of being we are. By the metaphysical deduction of the first truth, we come to the conclusion that being the second truth that we have the doubt, ie inked clear: it is our experience as res cogitans, ie as a thinking substance independent of the body (since we know that we exist as thinking without even knowing whether there is beyond doubt that the body).