Since philosophy investigates the ultimate causes of things, it is enough for it to part from unquestionable experience. It employs rational inference as its main instrumentality. Hence, it is experiential, but chiefly rational.
The Positive Sciences, on the other hand, seek exact data and, hence, employs chiefly scientific or highly rationalized methods and instruments to obtain them. They are rational systems of knowledge, but chiefly experimental in method.
a. The Philosophical Method of Inquiry
Philosophy uses the rational method in solving problems. The rational method means not only reasoning but also contemplation combined with and confirmed by experience, observation, reflection and tradition.
In this connection it should be pointed out that the two, reason and experience, the rational and the empirical method, must always combine to be used together in any investigation – to arrive at true and valid conclusions to any problem. In the empirical sciences such as Physics, Biology, Medicine, Etc. the experimental or empirical method is mainly used; while in Philosophy, reasoning or logic, contemplation, and reflection is used. There is no such a thing as a purely rational or purely empirical method of inquiry. Contrary to common claim, the experimental sciences also and necessarily employ philosophical reasoning, i.e., logic, in drawing conclusions, say, in passing from premises or given data to conclusions. To be valid, the conclusion drawn should necessarily follow from well established premises that necessarily imply the conclusion. It is to be noted herein that the logical connection that should exist between the premises and the conclusion cannot be perceived by the senses or even by all of them combined, but only by reason, by philosophy.
Moreover, the problem of man, being basically a moral problem, involves and contains non – empiriological components at its core, which cannot be revealed or disclosed by purely empirical and experimental analyses, however penetrating and efficient these may be.
To assume that the purely empirical method is the only valid method of inquiry in all fields of investigation, is fall into what Fulton Sheen aptly calls "the fallacy of the uniform method".