What you are if you practice PostModernism
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Literally, after modern. Rather than descriptions of people's practice, the term is more frequently used to describe architecture or literature more modern than modern.

Opponents of post modern views usually fall into the modernist or pre-modernist categories.

In SimpleThereforeWrong terms, the modern view is that the past does not matter or is not relevant, the pre-modern view is that the past is all important, must be held with the highest regard, traditions must be upheld etc.

The simple view of post modern attitudes is a synthesis of both these views, which sounds contradictory and illogical, and hence becomes the point where most left-brainers decide that the only value in post modern views is, at best, entertainment value, and that they should never be taken seriously.

However, it can be easily seen that neither the present nor the past hold all the answers, and that an eminently sensible view is to consider both the past and the present when plotting a course to the future, And maybe a bit of nonsense here and there is OK, even desirable.
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Used in a pejorative sense: Anti-science. 

While it is true that what's being called a post-modern critique of science is often perceived as anti-science, it is not accurate to call anything anti-science post-modern. What is true is that there are people who will attack others by calling their statements or positions post-modern, instead of using a reasoned argument, hence the pejorative sense.
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See also: PoMo, TheFeyerabendProject, PostModernProgramming