A person's pursuit of moral perfection requires careful attention to both their social environment and their internal world. True honesty and innocence stand in direct opposition to anything crooked or twisted [מצודת ציון, שטיינזלץ, מלבי״ם]. Achieving this standard demands a conscious decision about who to allow into one's life and what thoughts to harbor in one's mind.
The primary approach among commentators focuses on removing negative influences from one's social circle. A crooked heart is understood as a corrupt individual. To maintain moral integrity, a person must distance themselves from such people, refusing to welcome them into their presence or form connections with them [רד״ק, מצודת דוד, מאירי]. Consequently, the declaration of refusing to know evil is understood as a firm promise to avoid befriending or drawing near to a wicked person [רד״ק, מצודת דוד, מאירי]. This practical approach is grounded in human nature. Since the inclination toward bad behavior is ingrained in people from a young age, it is impossible to completely lack the knowledge of what an evil act is. Therefore, the rejection here must refer to distancing oneself from bad people rather than erasing the concept of wickedness from one's mind [אבן עזרא].
Conversely, another perspective shifts the focus inward, viewing this as a commitment to the purity of the soul. In this light, the declaration is a vow never to love or acknowledge evil deeds [רש״י, שטיינזלץ]. Taking this idea further, it describes a state of absolute inner refinement where a person has no mental inclination toward wrongdoing whatsoever. While most people must fight a constant internal battle against their urges to choose good, it is possible to reach a level where one's nature leans so strongly toward honesty that the very concept of evil becomes incomprehensible. This represents a return to a state of complete innocence, much like the first human being before the first sin [מלבי״ם].
However, the desire for such absolute internal purity raises a deep philosophical question regarding free will. If a person were to ask God to completely remove all crookedness from their heart until they no longer even recognized evil, it becomes unclear how they could earn a reward for their good deeds. The reward for keeping the Torah and its Commandments fundamentally depends on the presence of an opposing evil inclination. It is precisely the struggle to overcome this internal opposition through conscious awareness and deliberate choice that gives moral victories their value [אלשיך].