Can anyone point out a situation, based in real world events, or an entirely hypothetical situation, where it would be ok/right for someone to delude themselves into believing something false?
For instance, the psychosomatic effect of placebos can lead to people actually feeling better, and in some cases, actually recovering from illness. However, reliance on the placebo effect to cure people is not good medicine, and is even malpractice. Saying crystal therapy will cure someones cancer may make them feel more confident, lowering the mental and physical stress they feel, thereby increasing their bodies ability to fight the tumor/s. However, again, the placebo effect decreasing their stress levels may not be enough to effectively combat the cancer, ad so it would be wrong of a doctor to not ensure they clearly drive home the fact that their patient should not rely on the "alternative treatment".
Is there any valid situation anyone can think of where it's perfectly acceptable, or even necessary for people to delude themselves into believing a falsehood? I am not solely looking for examples that are related to physical health by the way.