In the broadest terms my goal in this work is to justify rights to intellectual property. Rule-utilitarians who offer incentives based arguments think that this goal is easily attained. Rights, they claim, should be granted to authors and inventors of intellectual property because granting such control provides incentives necessary for social progress. Society ought to maximize social utility, therefore, temporary rights to intellectual works should be granted. This argument is typically given as the primary justification for Anglo-American copyright, patent, and (...) trade secret institutions. ;First, a negative argument is given that undermines rule-utilitarian arguments for intellectual property. I argue that internally, on their own grounds, rule-utilitarian arguments fail to justify rights to intellectual property. It is also argued that rule-utilitarianism faces a number of serious objections that may lead to its rejection as a plausible moral theory. ;My positive argument begins with an account of Locke's proviso that justified acquisitions of unowned objects must leave enough and as good for others. One way to interpret Locke's requirement is that it ensures the position of others is not worsened and this can be understood as a version of weak pareto superiority. If the possession and exclusion of an intellectual work makes no worse off, then the acquisition ought to be permitted. ;I argue that rights to intellectual works can be justified at both the level of acts and at the level of institutions. At both levels my argument turns on two features of intellectual property. Given that the frontier of intellectual appropriatable items is practically infinite and that the same intellectual work may be created and owned by two or more individuals, the case for Locke's water-drinker and the author or inventor are quite alike. ;Finally, a Lockean account of copyright, patent, and trade secret is developed along with an analysis of privacy, power, and the ownership of virtual objects, in the new on-line information age. (shrink)