lm noir was itself a system of visual and thematic conventions which were not associated with any specific genre or story formula, but rather with a distinctive cinematic style and a particular historical period (Schatz 112).
Schatz's insistence on noting the relationship to a historical period is important because it indicates that film noir was a social, psychological, and aesthetic response to a certain sense of societal angst that developed first in the uncertainties of World War II, a period of world tensions manifested in the psychological ambiguities of film noir, and then continued in the new uncertainties of the Cold War period, especially in the years immediately after World War II when American society was straining to recover from the war while also trying to adapt to the new line-up of international friends and enemies. This also explains why the style became so pervasive, since it was speaking to the national psyche that existed at the time, and that psyche did not kick in only for one genre of film but was "in the air," as it were.
The true film noir took place in a black-and-white world,
for the proper environment for the darkness of the human soul was the black-and-white image of the city in the 1940s and 1950s:
The world of the hard-boiled myth is preeminently a world of black and white. Its ambiance is that compound of angular light and shadow enmeshed in webs of fog which grew out of the visual legacy of German expressionism in drama and film, transforme
...