  Cockburn’s philosophical reputation rests largely upon her polemical works in defense of John Locke and Samuel Clarke. While she displays a range of interests in these works, her primary concern is to defend a moral epistemology that combines elements of Locke’s epistemology with a proto-Clarkean moral fitness theory. Cockburn’s morality is best described as a broadly rationalistic natural law theory that draws strongly on Locke’s concept of reflection. According to Cockburn we discover the foundations for moral rules through reflection upon human nature and divine nature. Humans are then able to determine moral right and wrong by assessing the fitness or unfitness of given acts with reference to these natures.