Reason, broadly defined, is the faculty of conceptually integrating sensory data by using logic. This is a complex definition, but we can unravel it in three elements :
* Sensory data - what we receive from our senses.
* Concept-formation - the capacity to use and create concepts.
* Logic - the method used to uproot contradictions from our thinking.
To integrate our sensory data also requires us to use concepts and logic. To form concepts requires us to use sensory data and logic. To use logic requires us to use sensory data and concepts. Both represent one and the same faculty - Reason.
In practice, Reason is a collection of methods which we use in order to find knowledge, by objective evidence (that is, evidence found using the methods). All these methods must be based on the three elements we have seen.
Here are some of the methods that are used in science and rational reasoning in general.
* Making a hypothesis. Using observation and basic or intuitive reasoning, we can elaborate a hypothesis to explain something. But before claiming that a proposition is true, we must put it to objective test (in the case of science, by trying to falsify it, in the case of philosophy, by testing it logically or empirically, etc).
* Occam's Razor. When two hypothesis can explain the same facts, the simplest hypothesis is correct. This is a consequence of the necessity of objective evidence in order to know something. Why ? Because the entity that is superfluous has by definition no evidence to support its addition.
* Using the results of rational disciplines. There is no need to reinvent the wheel and re-do hundreds of years' worth of experiments when science has already done so. As such, we should treat claims that corroborate established science or philosophy as privileged, and claims that go against them to be dubious at best. Which leads us to...
* Skepticism. The demand for extraordinary evidence in response to extraordinary claims. If you make an incredible claim, you better have proportional evidence to back it up. This is merely a consequence of the demand for objective evidence and Occam's Razor.
For example, if someone claims that free-energy machines disprove the laws of thermodynamics, one would demand rigorous evidence for such an incredible claim. Putting up a show and displaying a wheel turning for a couple of minutes during a carnival sideshow is evidence, but not sufficient evidence.
