A builder who tears down a house to build a better one needs temporary accommodation. Descartes faces the same problem at the level of the whole life. His method demands that he suspend judgment about all received opinions until they can be placed on a sure foundation — but life cannot be suspended. Decisions must be made, actions taken, relationships maintained. The provisional morality is a set of maxims to make action possible while the fundamental project of rational reconstruction is underway.
The first maxim is conformity: obey the laws and customs of the country you live in, adhere to the religion you were brought up in, and follow the most moderate opinions of the wisest people around you. This is not intellectual cowardice but practical wisdom: while your own views are uncertain, you have no better guide than what has been tested by long experience and communal life. Deviation is not warranted until you have something better to put in its place.
The second maxim is resolution: once you have chosen a course of action, pursue it as firmly as if you were certain it was right. The paralysis of the doubting intellect must not transfer to the will. A traveller lost in a forest who wanders randomly from path to path will never emerge; one who picks a direction and walks it firmly will at least reach the edge. The criterion for action is not certainty but commitment.
The third maxim is Stoic in character: conquer yourself rather than fortune, and change your desires rather than the order of the world. What we cannot control — the external circumstances of our lives — we should not try to command. What we can control — our own thoughts, judgments, and responses — we should govern with reason. This is the principle underlying the third maxim, and it gives the provisional code a depth that mere conformism lacks: it is not a surrender to convention but a discipline of the inner life in the absence of certainty about the outer.
The provisional morality is set out in Part III of the Discourse on the Method. Descartes' debt to Stoic ethics — particularly to the distinction between what is and is not in our power — is explicit. The same themes appear in later treatments of Cartesian ethics by Descartes' followers.