Opponents of capitalism often claim that this system takes insufficient account of the needy. Defenders, e.g. Milton Friedman and other members of the Chicago School, counter by adducing the benefits of capitalism for the poor and the deficiencies of competing systems. Ayn Rand, a philosopher and novelist who founded Objectivism, adopted a more radical view. She denied any obligation to assist the needy as a class. Each person possesses certain natural rights, which include freedom from aggression and the liberty to acquire property. For each person, his or her own life as a rational being ought to rank as the highest good, and one's pursuit of this good faces no limitation from positive obligations unless one has voluntarily contracted with someone to perform some service. In the absence of agreement, one's only obligations to others are to observe their negative rights.