Our Gemara on Amud Beis quotes a verse in Vayikra 4:28 which uses an ambiguous phrase regarding a sin-offering, “Or, if his sin be known to him.”  The phrase seems to emphasize knowing about the sin, but it is redundant, as how would he bring a sacrifice if he did not know about his sin?  From there the Gemara derives a number of rules relating to what kind of information obligates a sacrifice, and what does not.  If he is told he sinned by two witnesses, which is the highest legal level of verification, even if he denies sinning he is obligated to bring a sin-offering according to Rabbi Meir.  (The rabbis argue with Rabbi Meir on this point). If on the other hand a single witness confronts him, if he denies the allegation, everyone agrees he is exempt from the obligation to bring a sin-offering. If he is merely quiet, his silence is taken as a tacit admission and he is therefore obligated. 

They Shem MiShmuel (Vayikra 4) goes for a deeper look into the morality behind these halachos. He says, knowledge in the form of discernment between what is and is not, is the key to understanding anything. When one sins, the effect of the sin clings to him and entangles him like ropes. It’s toxic influence is liable to follow him to the grave. The remedy is full knowledge of what he has done wrong so that he can distance himself from all it’s damaging effects, by recoiling in horror. He can come to this place of cleansing and removing the defects of his character only by realizing the damage he has wrought. This requires brutal self honesty.

This is why it is not enough to hear from a witness that he sinned, he must come to an understanding where he can admit to himself that he sinned. Without that, obtaining forgiveness is an empty exercise. (When confronted by two witnesses, Shem MiShmuel reasons that their veracity is too powerful and breaks through any self-deception, at least according to Rabbi Meir. According to the Sages, his refusal to admit is no worse than an intentional sin which anyway does not qualify for a chattas offering.)

The Tiferes Shlomo on Bereishis (3:8-11) has a fabulous derash on this idea of self deception. After Adam and Chavah ate from the Tree of Knowledge, as they hear the voice of God traveling through the Garden, they hide themselves. When Hashem calls out, “Where are you?” Adam answers, “I was afraid because I was naked, so I hid.” Hashem then said, “Who told you that you were naked? Did you eat of the tree from which I had forbidden you to eat?”

Of course the pashut peshat is that God is giving Adam a chance to retract his story, by prompting him to admit his wrongdoing (see Rashi ibid verse 9). However, if Tiferes Shlomo reinterprets this creatively as follows: Adam says, “I realized that I was bereft and completely naked of any merit, so I was scared and hid.” Hashem answers, and wonders, “Who told you? How is it possible that you made such a frank assessment of your wrongdoing instead of offering up a rationalization to justify your behavior? Who helped you understand how truly naked you were?”

It is good to be reminded of the fourth step of the Twelve Steps: Made a searching and fearless moral inventory of ourselves.