In 1841, Justice Story famously said that '[p]atents and copyrights approach nearer than any other class of cases ... to what may be called the metaphysics of law, where the distinctions are, or at least may be very subtle and refined'. This talk will explore some ways in which philosophical analysis of intellectual property law provides clarification of its subject matter, looking at two interrelated questions. First, what does it mean to say that the objects protected by patents, copyrights and trade marks are property? Are there philosophical reasons to be wary of such a classification? Second, how do conceptual differences between intellectual and tangible resources affect the normative arguments we might put forward to justify ownership of such resources?