Eugene Volokh has a post dissecting the claim that Saddam is a rational guy and therefore subject to deterrence even if he has or obtains weapons of mass destruction. He doesn’t cover every possible argument — like the possibility that Saddam could believe that he could get away with using terrorists to deliver WMD because he wouldn’t get tied to the attack — but the professor has the basic point that Saddam’s goals may not necessarily be all about sheer survival, and that a WMD attack might at some point play into a desire for historic glory on his part. Also, remember that Saddam is not a young man; if he grows sick or weak, he may see going down in a blaze of glory as preferable to steadily losing his grip and being removed quietly.