According to Parsons (2020)

[Jeff Rubard]

It is evident that such terms as "fact" are much in need of definition. This will come later. At the present juncture against the view just roughly sketched may be set another, namely, that scientific " theory " - most generally defined as a body of logically interrelated "general concepts" of empirical reference - is not only a dependent but an independent variable in the development of science. It goes without saying that a theory to be sound must fit the facts but it does not follow that the facts alone, discovered independently of theory, determine what the theory is to be, nor that theory is not a factor in determining what facts will be discovered, what is to be the direction of interest of scientific investigation.

Not only is theory an independent variable in the development of science, but the body of theory in a given field at a given time constitutes to a greater or less degree an integrated "system." That is, the general propositions (which may be, as will be seen later, of different kinds) which constitute a body of theory have mutual logical relations to each other. Not, of course, that all the rest are deducible from any one - that would confine theory to the one proposition - but in the sense that any substantive change in the statement of one important proposition of the system has logical consequences for the statement of the others. Another way ff of putting this is to say that any system of theory has a determinate logical structure.

Talcott Parsons, *The Structure of Social Action*