This chapter discusses and analyzes the phenomenon of pathological bifurcation among French engineering students. Pathological bifurcation occurs when sustainable development succeeds in inspiring student activism, but that passion expresses itself destructively. The chapter answers two questions. First, we interrogate whether pathological bifurcation is a product of lacunae with current SD education practices. Having answered affirmatively, we reflect on how to treat this diagnosis. Our suggestion is that if SDG related curricular innovations are desirable, so too is an extensive grounding in the traditional teachings of what we call planetary humanities. These are lessons drawn from around planet inculcating the very traditional moral art of controlling one's passions in such a way as to best foster collective flourishing.