Philosophy

Descartes scepticism and principle of eternal doubt leads to one major question. What therefore is truth With the assumption that dreams are not real and that it can mislead one to arrive at truth, the first prerequisite to arrive at truth to know that one is not dreaming. One must also know that he is not being tricked by a wicked demon.

If one knows already that he is not dreaming, then one can assume that he is in the real world. But here another problem arises.  Everything that we perceive in the real world with our senses can be doubted. In fact our senses can also deceive us. And if one can doubt anything in the real world, then if follows the real world may or not be true. Since all things can be doubted, there is only one thing that cannot be doubted. This is the fact that one doubts. Thus this is one of Descartes major premises All things can be doubted and the only thing that cannot be doubted is that one doubts. One doubts because one thinks. Thus Descartes foundational philosophy is Cogito ergo sum-- I think and therefore I exist.  Using this philosophical foundation, he argues that truth can be arrived at through human reason alone.

The next step that Descartes took is to ask the question Are there things that exists outside my consciousness How can one be sure that one is not deceived How can one really be certain about the existence of the external world

Even if the senses can deceive us, Descartes proceeded that only the primary measureable qualities of the external world exists such as shape, number, size, quantity, location, extension and others. Only these quantifiable characteristics and mathematically calculable properties of things can exist without doubt and can exist independently of our consciousness.  This way, logical empiricism as a scientific method and philosophy was born. Thus follows the Cartesian dualism of mind and body.

Yet the problem persists because still the first premise maintains that all knowledge of external things exist only in the mind.  Two opposing arguments thus battle each other rationalism in which all things are constructed by the mind and empiricism in which all things all valid knowledge can only come from sense experience. The whole argumentation trips on itself and becomes a contradiction. If the only thing real are my ideas and thoughts, then the external world tantamount to nothing but a creation of my ideas.  However if only the primary measurable qualities of the external world is true outside of my consciousness, then my ideas are mere subjectivisms which can be falsified by the external world.

If  X represent mind, and P represents the external world, the argument would go this way
If X can know something about P, then P exists.
If X cannot know something about P, then P does not exists.
 Yet the problem with Descartes is that he argues that
P exists, yet X cannot know something about P

This compels Descartes to bring into the argument his discourse on the existence of God.
Descartes argues that if one can think, there must be a first cause and that is God. If I can think therefore God exist and if God exist who is external to us, then the outside world must also exist even if it is different from the mind.