A Garland of  '-isms':   Some key terms in Brown's  Who Rules

(Social) Constructivism-- generally, the view that science is shaped by cultural biases and presumptions;
 we construct our picture of the world--our own subjective viewing has more to do  with what we see than
 any independent reality.

Empiricism--all knowledge is based on sensory experience; there is no other source of knowledge
 (by contrast to Rationalists, below)

Essentialism-- especially in the debate over gay rights, the view that sexual orientation
(or any social behavior) is determined or predisposed by biological causes: it is 'essential' 
or intrinsic to the person's physical makeup, not a matter of free choice.

Instrumentalism -- treats scientific theory as merely a means or instrument to explain phenomena: 
the constructions of theory, such as Ptolemy's epicycles, are not (necessarily) a description of the underly-
ing reality (by contrast to Naturalism, Positivism, and  Realism, below)

Naturalism -- the view that 'the natural world is all there is.'  Rather like the Positivists, these thinkers 
regard anything other than science as largely meaningless for knowledge (aesthetics may be pleasing,
 religion is comforting, but meaning-less notions).	Ethical rules (or norms) are a product of evolutionary
 process (like the incest taboo).   Especially important in this regard is David Bloor's 'sociology of scientific
knowledge' for its 'strong program', insisting that the same rigorous methodology of science be applied to 
the social study of science in practice.  

(Logical) Positivism--  the radically empiricist school of thought associated with the Vienna Circle of the 
1920s and early '30s. They relied on verificationism-- any statements not testable are meaningless.

Rationalism-- In this context, the rationalist position is that certain forms of knowledge derive from
 pure reasoning (perhaps based on innate or a priori truth).

Realism-- "the aim of science is to give a true description of reality."  This means that scientific theories 
are literally true (or not), not metaphorically  'true'.  The truth is independent of our belief (perhaps 
quite remote from it), and has nothing to do with social construction.
 Note that in this sense, Brown can say that both atheists and fundamentalist are realists about 
'the God theory': whether one believes that there is or isn't a God, both believe that their convictions 
are a description of reality.

Scepticism   (or skepticism): the view that there is no reliable evidence (contradicting the third element
 of realism); none of the tenets of science have any real proof.
 
Values:  In this context, 'values' are 'ought-statements'; they derive from rules or 'norms'. 
Brown is interested in epistemic  or cognitive  values involving rules about how to do good science.

Verificationism-- Esp. as a tenet of Positivism, the principle that only what can be tested is meaningful.