Answer: According to the Rambam, the fact that the Torah recognizes the realities of the society in which it was given does not mandate those acts. At the time the Torah was given no one could envision a society without slavery. Later, slavery was discontinued (when it was still normal in the non Jewish world).
I don't think it is proper to say that the Torah has a position on slavery today, but that all societies must be rule by concern for human dignity and lovingkindness. In our world, slavery is a function of greed and power. The Torah does not mandate these things.