Free will that includes the power to do evil purely for evil is not desirable because it would destabilize morality, happiness, social order, and psychological health. How? It would be so dark and effectively supernatural/magical that nobody would want it to exist.
We can tolerate harms that contain the seeds of their own destruction and turn to good but not that. We fear that we may do evil purely for malice and chaos and hide it under excuses. We fear it has some power to transmit itself into us or plant evil seeds in us. We tend to treat evil however as a real power or substance at times while claiming to regard it as a mere lack of good. We are not trustworthy then.
Out of pride and the desire for comfort, we formulate free will and morality to suit ourselves. They become a crutch. The fact is that makes our affirmation of free will and morality depend on suspect motives and desires.
All people act according to what they believe is best given their circumstances. No one chooses an action purely because it is “evil” or “wrong” in itself; rather, actions judged by others as wrong are taken because, in that moment, they appear beneficial, necessary, or unavoidable to the person acting. In other words, choices are guided by internal and external influences—desires, knowledge, habits, and context—not by an ability to choose independently of these factors.
If someone performs an action that is wrong, they do so because they perceive it as the best available option. Misjudgment, error, or ignorance may lead to harmful outcomes, but these actions are always conditioned by prior causes and perceptions. No one deliberately chooses evil as an abstract principle; they act according to their programming, whether inherited, learned, or situational.
Some definitions of free will require that a person could have chosen otherwise under the exact same conditions. By this standard, our choices are not free, because every action arises from prior causes—biology, environment, culture, mental state—and could not have occurred otherwise given those causes.
However, if we define free will in the strict sense of choosing evil for the sake of evil itself, we lack evidence that anyone ever acts this way. People may commit harmful acts, but always for reasons they perceive as justifiable, necessary, or desirable. Because no one is known to choose evil purely as evil, this could be taken as indirect support for the impossibility of free will in the absolute sense.
In practice, we feel free because our desires align with our actions. This psychological experience is important for well-being, but it is not proof of metaphysical freedom. We are determined agents acting according to our programming and context. Feeling free is useful, but it does not establish actual freedom in the strict, philosophical sense.