The butterfly-or-man problem isn't far-fetched. For instance, there is the case of a man who sleeps and has a dream and the events and arguments in the dream are as rational and congruous to him as he has the sense of rationality and congruity during his waking hours. However, on waking up, he is shocked to realize that the dream arguments were inconsistent and incongruous, but wonders that they possessed strong credibility and sense during the dream-state or the semi-waking state.
Much similar might be the case of a lunatic. Yet, psychologists observe that humans possess some form of lunacy at given moments. For instance, take the case of an angered man who is convinced that his anger is justified until he comes to his senses.
Therefore, the Scriptures advise us not to trust in our own understanding, but trust in the Lord with all our heart.