 Advocates of welfare-based principles (of which utilitarianism is the most famous) do not believe the primary distributive concern should be material goods and services. They argue that material goods and services have no intrinsic value but are valuable only in so far as they increase welfare. Hence, they argue, distributive principles should be designed and assessed according to how they affect welfare, either its maximization or distribution. Advocates of libertarian principles, by contrast to each of the principles so far mentioned, generally criticize any distributive ideal that requires the pursuit of specific ‘patterns’, such as maximization or equality of welfare or of material goods. They argue that the pursuit of such patterns conflicts with the more important moral demands of liberty or self-ownership. Finally, feminist critiques of existing distributive principles note that they tend to ignore the particular circumstances of women, so feminists tend to argue for principles which are more sensitive to facts such as that women often have primary responsibility for child-rearing and on average, spend less of their lifetimes than men in the market economy. 