Clarke's ethical theory of "fitness" is formulated on the analogy of mathematics. He held that in relation to the will things possess an objective fitness similar to the mutual consistency of things in the physical universe. This fitness God has given to actions, as he has given laws to Nature; and the fitness is as immutable as the laws. The theory was criticized by Théodore Simon Jouffroy , Amédée Jacques , Sir James Mackintosh , Thomas Brown , Francis Hutcheson , and others,  but substantially defended by John Balguy against Hutcheson's sentimentalist case against moral rationalism. A similar form of moral rationalism is developed by the Cambridge Platonist Ralph Cudworth .