"The opinion which we entertain of our own character depends entirely on our judgments concerning our past conduct. It is so disagreeable to think ill of ourselves, that we often purposely turn away our view from those circumstances which might render that judgment unfavourable. He is a bold surgeon, they say, whose hand does not tremble when he performs an operation upon his own person; and he is often equally bold who does not hesitate to pull off the mysterious veil of self-delusion, which covers from his view the deformities of his own conduct. Rather than see our own behaviour under so disagreeable an aspect, we too often, foolishly and weakly, endeavour to exasperate anew those unjust passions which had formerly misled us; we endeavour by artifice to awaken our old hatreds, and irritate afresh our almost forgotten resentments: we even exert ourselves for this miserable purpose, and thus persevere in injustice, merely because we once were unjust, and because we are ashamed and afraid to see that we were so. …
"This self-deceit, this fatal weakness of mankind, is the source of half the disorders of human life. If we saw ourselves in the light in which others see us, or in which they would see us if they knew all, a reformation would generally be unavoidable. We could not otherwise endure the sight."
It may be that modest degree of self-deceit about our own capabilities and appearance helps many of us to get up in the morning and face the day. But self-deceptions have an unpleasant habit of colliding with reality, sooner or later. One hopes that those collisions with reality can be gentle, and that they can be an opportunity for what Smith called "a reformation" and what we now label as a "personal growth opportunity." But it's easy to think of situations where people become so highly invested in self-deception about their own conduct that, when the collision with reality occurs, they push back with anger and counter-accusations and retreat further into their self-deceit, rather than engaging in self-examination. Indeed, I offer as a hypothesis that 21st-century culture may in various ways encourage self-deceit over self-examination.