Among the
diagnostic criteria for BPD, one is the presence of "transient stress-related paranoid ideation, delusions or severe dissociative symptoms." I am going to clarify that "delusions," in this context, refers almost exclusively to what psychologists term "non-bizarre delusions," as opposed to "bizarre delusions." This, of course, raises the question, "What is a 'non-bizarre delusion,' as opposed to a 'bizarre delusion'?"
A delusion is a paranoid, frightful belief one holds in the absence of
evidence and even in defiance of all evidence.
A "bizarre delusion" is
an implausible delusion that defies all laws of science. If I insisted
to you that dove feathers were sprouting from my face, when you could
clearly see that that wasn't happening, that would be an example of my holding a "bizarre
delusion."
By contrast, a "non-bizarre delusion" is a delusion that is not
necessarily implausible -- and which actually comports with the laws
of physics and science -- but still lacks evidence. For instance, if I
said that everyone ogled me and wanted to rape me, that would not defy
the laws of physics; that's not impossible. But if you observe that, in
fact, people interact with me all the time without ogling me, then you
may be observing my having a non-bizarre delusion.
