  Cockburn takes up the defense of Samuel Clarke’s theory in later works. Her first defense of Clarke was made in Remarks upon some Writers. Here we find the language of ‘fitness’ occupying an even more prominent place than it had done in the Defence. This is only natural, given that the work is partly devoted to a defense of Clarke’s fitness theory, which had come to prominence in the intervening years. Throughout her discussion, Cockburn maintains a commitment to the basic view that morality is founded in the nature of humans and God. She sees this view as cohering with the general concept of fitness that she locates in Clarke and his followers. In the Remarks upon some Writers, Cockburn responds to critics of Clarkean moral fitness theory. These critics attack Clarke from a shared basic view of morality as a system of laws expressing God’s will. These laws are enforced by rewards and punishments that obligate by appealing to the fundamental human desire for happiness and freedom from pain. Rewards and punishments are thus seen as the fundamental means of harmonizing God’s will and human interest. Their main objection to fitness theory is that fitness relations are not primitive moral constructs, but actually presuppose more primitive constructs – i.e., God’s will and human interest. Clarke’s theory is accused of failing to provide sufficient account of these fundamental facts of divine and human nature. Cockburn responds to this line of criticism by arguing that fitness theory in fact rests upon a more robust conception of the relationship between the will of God and human interest than do the voluntarist accounts offered by Clarke’s critics.