In the same way that materialism is a necessary foundation for any social science, existentialism is a necessary foundation for materialism.  Materialist explorations help take incoherencies and inconsistencies out of ordinary explanations.

Left politics applied to social issues, i.e., political correctness, was originally an attempt to show that values are situation dependent, i.e., "relative."  The right, however, may try to turn left values, such as anti-harassment, on their head by making them into absolutes.  The response to this should be, e.g., that if someone does not feel harassed, then he or she is not being harassed

Custom mediates between class consciousness and cultural development.  Casual "friendly" conversation between persons of unequal rank and socioeconomic status, for example within an organization, can be construed, on the one hand, as an unconscious admission of the injustice of the current arrangement, and, on the other hand, as a step toward a more advanced arrangement.