The basic philosophical argument employed by proponents of perpetual copyright presupposes that intellectual property ownership rights are analogous to other property rights such as those associated with material goods. Proponents such as Mark Twain and Jack Valenti have stated that owners of intellectual property should have the same perpetual right to retain and bequeath this property to their descendants that owners of material goods already possess. Jonathan Zittrain, a faculty co-director at the Berkman Center for Internet & Society, illustrated this argument using the analogy: "makes no sense to imagine somebody after a certain time coming in and taking your rug or your chair and saying 'Sorry, your ownership expired.'"