  It is generally held that desires come on a continuum of strength: desires can be stronger or weaker. The strength of a desire is typically said to be constituted by the desire's causal power regarding the control of action: for one desire to be stronger than another is for the agent to be disposed to act upon it, rather than the second desire, in a situation in which (a) all else is equal, and (b) the agent believes that each desire is satisfiable by a distinct action, and (c) the agent believes that the desires are not jointly satisfiable. This way of characterizing desire strength is obviously most suited to an action-based theory of desire. But for each theory of desire there is a corresponding theory of desire strength available. Desire strength could be determined by the amount of pleasure or displeasure apparent satisfaction of the desire would bring, or by the degree to which a state of affairs seems good, or by the degree to which one's attention is drawn to the reasons to bring some state of affairs about, or by the amount of reward-based learning apparent satisfaction of the desire would cause, or by some average of all of these.