Even if you agree that rights exist independently from any written record of those rights, there is still the fact that the public's concept of rights tends to

Even if you agree that rights exist independently from any written record of those rights, there is still the fact that the public's concept of rights tends to change as culture changes. Despite the efforts of philosophers to connect rights to something more permanent than public opinion, the fact is that the key reason why we have rights is that we believe we have them. If we ceased to believe surely our rights would also go away. In that sense, it is extremely helpful to have a document that attempts to make a permanent record of what are rights are and what we should expect from our government. The fact that such a document is (necessarily) incomplete does not make it any less valuable.