On the face of it, self-deception seems impossible — or, at the very least, paradoxical.
How can someone tell a lie to herself?
Maybe I believe that I am just as good at basketball as Kobe Bryant.
But I’m not, so I don’t.
Ok, but maybe I practice every day, shoot hoops every night until dawn, and I grow more and more arrogant. Eventually, I do convince myself that Kobe should fear me on the court.
You want to challenge me to a match? Well look out. I now believe that I am just as good at basketball as Kobe Bryant.
As I write this, I don’t believe this at all.
But could I ever come to convince myself of this?
If I believe my lies then I have fooled myself. I am both the deceiver and the deceived.
This is the paradox.
As a deceiver she must believe that [not p], and, as deceived, she must believe that [p]. Accordingly, the self-deceiver believes that [p] and [not p]. (The SEP)
And yet, despite this apparent logical contradiction, self-deception is very real.
How do I know? Because I have been in it.
This cognitive state is uncomfortable to be sure, but it can be done. And you will see how this is possible when I sketch in the details a bit.
Begin by replacing “she must believe that p” with the following:
She wants, with every fiber in her body, that p, so she seeks out supporting evidence for p.
So what does she do?
She racks her memory, looks for articles on the Internet, and she eventually allows herself to bask in the comforting thought that p cannot be ruled out entirely.
She sits again in this hopeful state, satisfied with the “evidence” that she has gathered — the evidence that she looked to find.
With this information in her head, she continues to hold onto the hope that p could become a reality.