Does marxism follow the aproach of Social Science or Natural Science?

Excuse me if its a dumb question but after reading about Praxeology and the Social Sciences aproach I was convinced that marxists used the Natural Science aproach to the study of society in their “Dialectical Materialism”, yet in a debate with a marxist he claimed that they too use the Social Sciences aproach in the LTV and their analysis of the dialectical, although he admitted that he dismissed Praxeology out of hand because it was too “simple” but at the same time he agreed that men act with a purpose.

Isnt accepting that men act with a purpose invalidates the Historical Materialism theory of class antagonism?

Isnt accepting the method of Social Sciences implies necesarily to accept the Praxeological approach?

Am I missing something?

If anyone has trouble understanding my question, I can refrase it.

I speak spanish, sorry.

They use the dialectic. Dialectics is unreason.

See http://en.wikipedia.org/wiki/Dialectic and http://en.wikipedia.org/wiki/Dialectical_materialism

Edit: to be more clear, hegelian dialectics and dialectical materialism are nonsense. Dialactics in the broadest sense isn’t unreason.

He didn’t use either.

Marxians and Austrians have a lot in common. Both use a deductive method. Both incorporate dialectics. Both correctly interpret the state as exploitative. Followers of both camps like to label other schools of thought as “tainted ideologies” (e.g., Bourgeois economics, positivist economics).

I would caution anyone calling out Marx’s method since it is very similar to the Austrian method - minus the axiomatics. In a way, Austrians are mutant descendants of Marx. Almost everything Marx did was pure deduction, though he began at a false starting point - the labor theory of value. The Austrian method is much more rigorous and Mises (as well as Bohm-Bawerk) paid much more attention to epistemological issues than did Marx.