The relation between theory and observation is unilateral in the sense that theories are dependent on observations whereas observations are theory-independent.
To a given set of observation-statements, there corresponds uniquely a theory such that we can deduce the latter from the former.
Our factual judgments are value-neutral and our value judgments have no factual content (fact-value) dichotomy). Science, being the paradigmatic instance of actual inquiry, does not have any value commitments.
All scientific explanation must have the following pattern.
L 1 … L n
I 1 … I n
Therefore E
Where L 1 … L n is a set of laws, I 1 … I n is a set of statements describing initial conditions, and E is a statement describing the phenomenon to be explained. In other words, to explain a phenomenon is to deduce its description from a set of premises constituted by laws and statements describing initial conditions. In sum, all explanation involves deduction. An explanation which does not have or cannot be recast into the pattern given above is not a legitimate scientific explanation (deductive nomologism).
The progress of science consists in the increasing accumulation of observations and the cumulative growth of our theories.
The objectivity of science is guaranteed by the fact that our scientific theories based upon indubitable observations. Our observations can be indubitable because they are or can be shown to be theory-independent.
The aim of philosophy of science is to discover and systematize those universal and changeless norms which science follows and by following which science has become the most rational enterprise. Philosophers of science seek to understand science in terms of these norms which determine scientific practices. In doing so, they provide an account of science which is normative. Since these norms constitute the very logic of scientific practices, philosophers of science provide what may be called a logic of science.