Proving that progress is a myth shows that there is still and will always be a place for political theory (this is a relief to me, as I'm investing a good deal of my life in political theory right now). And yet, the fact that political theory will never be "solved," but rather will continue to be a problem does not mean that we shouldn't be serious in our attempt to institute the best possible order for the time. Benedict XVI writes,

[E]very generation has the task of engaging anew in the arduous search for the right way to order human affairs; this task is never simply completed. Yet every generation must also make its own contribution to establishing convincing structures of freedom and of good, which can help the following generation as a guideline for the proper use of human freedom; hence, always within human limits, they provide a certain guarantee also for the future. In other words: good structures help, but of themselves they are not enough. Man can never be redeemed simply from outside.