The term self deception is sometimes used in a very loose way. It is easy to put ‘self’ in front of ‘deception’ when the self has been passive in accepting a falsehood. When someone believes something false, and we consider that false belief unreasonable we may say, but say wrongly, that the person is self deceived, when we mean only that we believe what is false and could believe what is true instead. He is simply deceived. That deception may be the result of someone deliberately telling him a falsehood, or it may be the result of not his not having looked into the evidence adequately. In any case he is simply deceived. But he has not, even if it is possible, deliberately deceived himself.
If we are going to speak carefully we will distinguish believing something false, from self deception even if self deception entails believing something false. Something more has to be said.
So we shall distinguish two kinds of false believing: (1) believing falsehood, not knowing it is false. (2) believing falsehood, knowing it is false. Let’s take these in turn.
(1) is a common enough occurrence. There are enough agents who will benefit from our believing falsehoods, or not believing a truth: salesmen, politicians, come immediately to mind. There are other motivations than gaining profit or power for an agent to tell you and hope you will believe a lie. Why do parents tell children lies about Father Christmas, the Easter bunny, etc.? Motivations differ but the different instances have something in common. I am led to believe a falsehood because of the initiative of another person, or of a community,.
When I am unaware that the falsehood I believe is false, I may be content with it. On the one hand I may not have an awareness that there are alternatives. What chance does a young child stand when the adult world conspires to have it believe the fabrications about Santa Claus? In due course the once deceived person may learn that what he has believed is false and then will abandon the belief. He may or he may not find an alternative that is reasonable and true. The rational thing to do at any rate is to abandon the belief I know to be false.
(2) The second case is that I may know that what I believe is false and still retain the false belief. This differs from (1) in my being aware of the status of my belief. I know it its false, and so irrational to believe it. I believe it nevertheless. So some response, activity, failure to arc on the part of the self is required for self deception to occur. The self is here involved as it is not in the case of being deceived by a third party. Since such self deception is irrational we can ask whether it is really possible. If we answer that it is, we must then conclude that human existence is often irrational, that there is an endemic irrationality to our human condition, and that (as Paul has said) would be wretched indeed.
by Dr. Edward W.H. Vick, retired professor and author of Death, Immortality and Resurrection, From Inspiration to Understanding: Reading the Bible Seriously and Faithfully, Philosophy for Believers, Creation: The Christian Doctrine, History and Christian Faith and more!