Capitalism is the practical conclusion to absolute property rights.
If no person can use another's property, without that owner's consent, you have the ethical framework which concludes, in practice, capitalism.

Now, to denounce capitalism, is to denounce the individual's right to his property (either in his body or external material) -- e.i. to advocate the theft of said property.

Can you provide a logically consistent argument in favor of theft? This must be an a priori argument, as the above argument (in favor of property) is a priori itself -- i.e. any empirical research, theory or evidence is irrelevant.