Naturalistic Rationalism or ‘rationalistic naturalism’
The scientific method uses a priori for the nature of reality or rationalistic naturalism.
The scientific method assumes a priori about the nature of reality, one is not agnostic about this, the scientific method is using philosophical rationalism as the nature of reality proof or truth by using a priori assumptions.
Knowledge can be classified in several ways. Firstly, it can be either explicit (self-conscious) or implicit (tacit, hidden from self-consciousness). Secondly, it can be either propositional or non-propositional (something which cannot be represented by propositions, e.g. knowing how to do something?).
Simply the scientific method requires certain a priori assumptions of epistemology and metaphysics in order to even get out of the starting gate. It assumes you are not a brain in a vat. The scientific method means that supernatural entities or concepts that are meaningless or logically contradictory cannot be included in a scientific hypothesis (not least because you can’t put a sample of a god in a test-tube). Consequently, when carrying out investigations scientists assume a position of methodological naturalism.
The idea that scientific evidence can disprove the notion of god is scientific realism. Scientific realism is also a priori rationalism about the accepted natural reality of nature. The point is a thing cannot validate itself science accepts what is reasoned, it may forget the philosophy it uses and cannot live without but it is still there. I can reasonably likewise assume a priori rationalism about the natural world that has no rational validity to a supernatural being called god.
To be scientific the knowledge must be
. communicable: It is something which is discussed.
. general: generalized vs. separate fragments of knowledge
. conceptual: represented by concepts vs. intuitive ideas (i.e. explicit and propositional knowledge)
. true or probable
. argumented: It can be proved or demonstrated.
The scientific methods should also fill some criteria, which try to guarantee quality of scientific knowledge. (These are important and quite permanent part of general paradigm of science):
. progressive: knowledge base is expanded by using this method
. self-correcting: the errors get corrected by this method.
. publicity: arguments are public for anyone
. justifiable: the arguments are satisfactory