In the Fourth Objections, Arnauld wrote:

The circular argument or strategy identified here has come to be known as the Cartesian Circle. The Circle is constructed from two arcs. The first is that certainty of the truth of clear and distinct perceptions depends on God's attributes. In the Fourth Meditation, for example, Descartes uses the Third Meditation understanding of God to prove the rule that everything perceived with clarity and distinctness is true. The second arc is that certainty of God's existence depends on a proof from clear and distinct premises.

Descartes was not impressed by Arnauld's observation. He responded by saying that an adequate explanation was found in his Second Replies and added:

A vast literature has accumulated as the result of attempts to understand Descartes’ response and evaluate how successful it is. It is an attractive problem for scholars because it is, on the surface, so simple to formulate, and Descartes’ explicit treatments of the Circle are brief and cryptic. Moreover, the problem gains depth from its connection to central issues of doubt,method, clear and distinct perception, scientia, and the knowledge of God.