European Enlightenment Philosophy (seventeenth and eighteenth century philosophy) led to democratic revolutions and ultimately the commercial and economic reforms that led to our Industrial Revolution. At the height of this era, Immanuel Kant posed the categorical imperative process as representing common thinking about methods for deriving practical moral maxims (principles of action) and associated duties. The role of reflective thought in establishing and maintaining these maxims is emphasized here. The categorization of our maxims into their associated perfect and imperfect duties is reviewed so that absolute prohibitions (perfect duties or “duties of right”) can be understood as distinctly different from those volitional duties (imperfect duties or “duties of virtue”) that pursue wide objectives but with practical limitations. This latter category is shown to be particularly germane to environmental ethics and related advocacy organizations.