With regard to Bush's effort to ban therapeutic cloning, Virginia Postrel argues

there is also good reason to preserve the freedom to do research even when it's speculative. The proponents of the ban keep saying that the research isn't necessary, so outlawing it is justified. They are in effect demanding that science, an open-ended process of exploring the unknown, have answers in advance�and practical ones at that.

And she points to a couple of petitions: her own and another.