Methods of obtaining knowledge

Knowledge may originate or be derived from the following origins or methods:

Revelation, even Divine revelation, which may be directly from God or some other spirit, perhaps mediated by being included in a book such as the Bible.
Authority Knowlege based on authority may rely upon the reputation of an individual such as Aristotle or Einstein or perhaps on institutional authority such as that of the Catholic Church or Oxford University. Note that an authority may adopt knowledge upon other criteria such as divine relelation or observation as well as upon authority. Authority may have a political basis in the sense that some political process, perhaps involving status as well as simple voting, peer review, or comment. This is familiar to participants in academia.
Reason or logic. Taking other knowledge as data, by logical operations knowledge can be inferred. For example the theoretical construct, the electron, is derived by logical inferences from observations and experiment. Such knowledge, being derivative, can not be better than the knowledge upon which it is founded.
Observation, or experience. This may be more or less sophisticated ranging from a simple, "I saw" to carefully designed controlled experimentation.

Reference