Should traditional knowledge - the understanding or skill possessed by indigenous peoples pertaining to their culture and folklore and their use of native plants for medicinal purposes - receive protection as intellectual property? This Article examines nine major arguments from the moral, political and legal philosophy of property for intellectual property rights and contends that, as applied to traditional knowledge (TK), they justify at most a modest package of rights under domestic and international law. The arguments involve desert based on labor; firstness; stewardship; stability; moral right of the community; incentives to innovate; incentives to commercialize; unjust enrichment, misappropriation and restitution; and infringement and dilution. These arguments do, however, support “defensive” protection for TK: that is, halting the use of TK by nonindigenous actors in obtaining patents and copyrights. These arguments also support the dissemination of TK on the internet and via other digital media and the selective use of trademarks. The force of these conclusions resides in the importance of a vibrant public domain, and the absence of any plausible limiting principle that would allow more robust rights in TK for indigenous groups without permitting equally robust rights for nonindigenous groups.