The late Greg Bahnsen (1948–1995) wrote his dissertation under Dallas Willard at the University of Southern California offering “A Conditional Resolution of the Apparent Paradox of Self-Deception” (1978). (You can read it as a free ebook: “The Apologetical Implications of Self-Deception.”) In 1995, he published a summary article entitled, “The Crucial Concept of Self-Deception in Presuppositional Apologetics.” It’s a very helpful introduction to what happens practically, theologically, and philosophically when people are self-deceived.

He starts with some analytical work, illustrates self-deception from an everyday example, and finally looks at how this analysis applies to Romans 1 (where unbelievers know God but unrighteously suppress that knowledge).

1. Self-Deception in Philosophical Analysis

Bahnsen first explains in analytical categories what is going on when a person is self-deceived about a belief, looking at their beliefs, disavowals, rationalizations, and intentions.

The analysis of self-deception fostered here maintains that when S deceives himself:

1. S believes that p,
2. S is motivated to ignore, hide, deny (etc.) his belief that p, and
3. By misconstruing or rationalizing the evidence, S brings himself to believe falsely that “S does not believe that p.”

In order to preserve something about his own self-conception, S engages in motivated rationalization of the evidence so that he relies in his theoretical and practical inferences on the proposition that he is not relying in his theoretical and practical inferences on p.

He is morally culpable for this lie about himself because it is engaged intentionally, and yet he may not be aware of his intention since it has become habitual or, being self-covering, has become something he no longer thinks about (like falling asleep).

S obscures his dreaded belief that p, as well as his intention to obscure it by rationalizing the evidence.

Self-deception involves deception of the self, by the self, about the self, and for the sake of the self.

2. An Everyday Illustration of Self-Deception

Bahnsen then provides an example to illustration common forms of self-deception, using Mrs. Jones:

The principal calls her to say that her son Johnny (her pride and joy, her only child) has been caught stealing lunch money out of students’ desks.

The evidence is plain that Johnny is a thief, and this is the third time she has received such a call from the school.

She has also noticed money missing out of her own purse at home, and Johnny has been coming home with expensive items from the store.

Mrs. Jones shows the affective symptoms of believing the proposition that Johnny is a thief. She tries to avoid situations where she is likely to be reminded of his dishonesty. She moves to a new neighborhood, transferring Johnny into a new school, and refusing to put a phone in her new home. She keeps an unusually attentive eye on her boy, but will not admit that she does so, etc.

Yet on the other hand, since nobody in the Jones family has ever stooped to dishonesty, and Johnny is her one reason left for living in the cruel world, she persuades herself that Johnny could not have done the dishonest deeds reported by the principal.

She forgets the past evidence and supplies “more credible” explanations of present evidence (e.g., money is missing from her purse because she is so careless or forgetful).

She goes out of her way to express confidence in her son to others, makes a show of giving him mature responsibilities, and tries to do only what one who believed in Johnny’s virtue would do.

She avers that she has a fine boy who is a joy to her, a regular paragon of virtue. Nevertheless, she flies off the handle at him over trifling matters (in a way unlike the way she related to him prior to the principal’s phone calls).

She astonishes and embarrasses others by seizing on every oblique innuendo to defend Johnny’s honesty.

When neighbors get curious over her missing cash and Johnny’s new acquisitions, Mrs. Jones fidgets, blushes, looks away, answers in halting fashion or changes the subject.

She treats the evidence broached in an unusual and distorted way, all the while apparently satisfying herself that her interpretations are quite plausible.

In this situation we find it very natural to express the view that Mrs. Jones is self-deceived. The affective symptoms justify us in attributing to her the belief that Johnny is a thief. Because she cannot stand that thought with its attendant psychic discomfort, she is motivated to hide this information from herself and direct her attention to the evidence in odd ways.

She dissents from believing her son is dishonest.

She claims the school officials had a vendetta against Johnny and were framing the poor boy.

She leans on implausible interpretations of facts, ignores the best and most obvious indicators, and brings herself to believe that she does not believe in Johnny’s dishonesty. (She is not the mother of a crook!)

She fools herself about her awareness of the truth.

The symptoms of this false second-order belief are nearly identical with believing that it is not the case that Johnny is a thief. She conceives of herself as trusting this untrustworthy son, and while guarding herself against his untrustworthiness she enthusiastically affirms her belief in him to others. She meets all the criteria of self-deception as proposed above, and we are able to describe what she is doing without resorting to paradox.

3. Application to Romans 1

Finally, Bahnsen argues that this analysis of self-deception provides us with categories to explain the self-deception Paul unpacks in Romans 1, where unbelievers know God but suppress that knowledge:

All men know and hence believe that God exists. The revelational evidence is so plain that nobody can avoid holding the conviction that God exists, even though they may never explicitly assent to this belief.

We are justified in ascribing such a belief to men on the basis of their observed behavior in reasoning (e.g., relying on the uniformity of nature), in morals (e.g., holding to ethical absolutes in some fashion), and in emotion (e.g., fearing death).

Nevertheless, all men are motivated in unrighteousness and by fear of judgment to ignore, hide, and disavow any belief in the living and true God (either through atheism or false religiosity).

By misconstruing and rationalizing the relevant, inescapable evidence around them (“suppressing it”), men bring themselves to believe about themselves that they do not believe in God, even though that second-order belief is false.

Sinners can purposely engage in this kind of activity, for they also deceive themselves about their motivation in handling the evidence as they do and about their real intentions, which are not noble or rational at all. Thereby they “go to sleep” (as it were), forgetting their God.

Because the evidence is clear, and because the suppression of the truth is intentional, we can properly conclude that all men are “without excuse” and bear full responsibility for their sins of mind, speech, and conduct.

Given the elaboration of self-deception offered here, we can better appreciate what Paul says in Romans 1, namely, that “knowing God,” all men “suppress the truth in unrighteousness.” And we can assert non-paradoxically that unbelievers culpably deceive themselves about their Maker.

—Greg Bahnsen, “The Crucial Concept of Self-Deception in Presuppositional Apologetics,” Westminster Theological Journal LVII (1995): 1–31.