outline of language functions
three categories of functions--
L  within the  individual
relations with thought
reflective and public        (Descartes...Pinker)
causal, shaping thought  (Whorf..)
the focus of the Whorfians is often on L differences in words--lexicalization.  These differences might well be seen as cultural.
priming but not causing  thought  (JL)
do we think in French, etc or Mentalese? (Descartes, PInker, JL)
L may put us in contact with our thoughts, let us communicate them, and maybe create/prime them in some cases. (JL)
"For who doubts whether a Frenchman and a German are able to arrive at identical conclusions about the same thing though they conceive entirely different words?" (See Limber, 1977 for reference).
L enables a rich consciousness with  limits
maybe dreams too?
creativity--L can twist the mind into improbable and even impossible combinations of concepts.
"Limber swallowed his lips eating lunch."  

self-direction--"verbal recipes" guiding action
tying knots
language can interfere with cognition
verbal  overshadowing
including loss of imagery
functional fixedness
Stroop task
priming inadvertently

confabulation and related L filling a cognitive gap
rationalization, cognitive dissonance
effects of literacy/writing
interpersonal communication
social-cultural functions
define a group, having a common dialect (cf. birds)
narratives and story-telling
enable myths, science, and religions
could we have any of these without L?

L enables external "storage" of a culture's narratives via literacy