Descartes' First Meditation: Skepticism and the Search for Truth

5. Therefore, although these things - the old opinions that things exist and are as I perceive them - are very likely a form that is more reasonable to believe in than to deny, I will temporarily pretend to be doubtful that they are entirely false and misleading. 6. Assume, therefore, not that God - which is all goodness and the supreme source of truth - deceives me, but that a genius or evil spirit, an astute and powerful trickster, has put all its deceiving industry into thinking of the sky, air, earth, colors, shapes, sounds, and all other external things as illusions and deceptions to get my credulity. I impose resisting the wiles of the great deceiver.

Critique of Cartesian Skepticism

The critical question is why?

1. Establishing a universal and necessary truth: "cogito ergo sum."
2. Aims of this truth as others infer the existence of God.

Reasons for criticism:

1. We cannot affirm the existence of a thinking substance from the intuition of a multiplicity of disparate ideas and discontinuous thoughts.
2. To deduce other truths of a reason, we do not deserve absolute trust.

If we cannot achieve a single universal and necessary truth, should we refrain from making judgments and acting? It is impossible because our nature prevents us. What, then? Apply Cartesian skepticism sparingly.

Why?

1. Because this methodical skepticism - which requires searching for firm principles, advancing with caution and security, constantly reviewing our findings, and carefully considering the consequences - if not intended to establish universal and necessary truths, is useful for all research and serves as a guide for action.
2. Because applied sparingly, it eliminates premature or uncritical prejudices and opinions and ensures the fairness of our judgments.

First Meditation

1. I will check my old opinions because I know that sometimes I have taken the false for true, and everything built on it can only be doubtful and uncertain. It will not be necessary to examine them one by one; simply review the principles on which they rested.

2. Everything I've held so far as most true and sure, I have learned from the senses or through the senses, and these, as I have experienced on occasion, are misleading. It is wise to be wary of those who have once completely fooled us. (This refers to essential information.)

3. It seems harder to existentially doubt the information provided by the senses. I am writing this summary in my room, the noise of the street disturbs me, I've stocked water to avoid having to stop my work... these seem to belong to the "true" - but I could be dreaming.

4. But even while dreaming, there will be simple and universal things that are real and existing in a mixture which are made all these images of things that reside in my mind, sometimes they are true and real, sometimes fake and fantastic. Such things are corporeal nature in general and its extension, the shape of extended things, their quantity or magnitude, their number, the place where they are, the time which measures their duration and the like - the objects of mathematics -.

Thus, arithmetic, geometry, and other sciences that deal with things simple and general, without worrying about whether or not in nature, contain, apparently, something certain and indubitable, because I fall asleep or awake, I always add two plus three to get five, and a square has no more than four sides. It does not appear, for now, that truths so clear and apparent can be suspected of falsehood and uncertainty. But what if an omnipotent creator of my "cogito" would deceive me? Some will say that it would be repugnant to his goodness, but also I'm wrong, others prefer to deny the existence of God before giving up the truth, but then probably would deceive me.