¶ … Metaphysical Methods of Inquiry The philosopher Rene Descartes adopted what he called a 'metaphysical' or rationalist approach to understanding the world and the relationship of the human to the divine. In contrast to a physical approach a 'meta-physical' inquiry, as the word suggests, is a method of reasoning that takes the thinker outside of the physical world and confines the philosopher's focus to the mind when establishing what is true. The great strength of the metaphysical approach, according to Descartes, is that it is not polluted by the potential delusions of the material world, in contrast to an empiricist or scientific approach. Metaphysics is deductive, rather than inductive in nature. It makes suppositions based upon evidence, reasoning from first, established principles, rather than creating principles based upon sensory evidence. "But while my senses may deceive me about what is small or far away, there may still be other things taken in by the senses which I cannot possibly doubt...unless perhaps...

Given that Descartes believes certain persons are insane based upon his sense evidence is not justification enough: he could be mad, delusional or dreaming. That is why the human mind is better known and more trustworthy than the human body.
In terms of the value of metaphysics, it lacks the innate biases and subjectivism that often can corrupt evidence, such as when a person has poor eyesight or was simply in a bad mood because he or she skipped lunch when witnessing an event. Descartes' commentary highlights how 'eyewitness accounts' are far from reliable. Every night when we enter into a dream state we leave what we consider the real world. We believe we know for certain when we are dreaming and when we are fully awake, but that is based upon faulty sensations of the body. The rigorous inquiry of rationalism forces philosophers to question common sense notions and to demand a more stringent justification for relying upon 'gut' feelings.

Descartes ultimately uses…