Extremism, which is variously regarded as the adversary of peaceful moderation or the vanguard of righteous dissent, often is immediately recognizable, but sometimes it may be ambiguous, insidious, or undefined. Growing apprehensions about mainstream extremism reflect a linguistic contraindication that may be a symptom of cultural disorientation. Insights from neuroscience suggest that some forms of extremism may arise from an imbalance of brain pathways involved in moral reasoning, such that those signaling sacred valuations and rule processing attain dominance over those representing empathy and deliberative reasoning. If the brain be compared to an orchestra, extremism would be analogous to the unpitched percussion section taking over, the bass drum and clash cymbals intruding into orchestral harmony and drowning out the string and brass sections with harsh, metronomic, auditory hyperintensity. And yet there is a proper role for these instruments. The ideal balance, whether of neural signals or orchestral voices, requires discernment of value beyond factual information. A number of ethical approaches supply moral clarity to assist with making ethical distinctions when convictions reach into the extreme, and while helpful, these leave unanswered deeper questions of ultimate meaning.