Abstract

The dissertation is a conceptual investigation into the logical structure of practical reasoning. Its most fundamental notion is an intentional concept of desire, which contrasts with non-intentional conceptions in that it is identified by its object, which is that towards which the desire motivates. The claim is that an adequate account of practical reasoning, including phenomena such as being guided by a reason, acting out of duty, willing, intending, and acting on principles and values, could be given based on this single concept. ;The strength of a desire is defined with the help of the notion of motivational conflicts: a desire is said to be stronger than a conflicting desire if it prevails over it in such a conflict. It is thus a fundamental conceptual principle that we can never act against our strongest present desire. ;A distinction is made between two fundamental processes of practical reasoning: The principle of derived motivation in which derived desires are formed in the service of end desires, and the process of deliberation in which conflicting desires are weighed against each other. The intentional nature of desire and the phenomena of derived motivation are claimed to be conceptually intertwined, for the phenomena of derived motivation is a main criteria for attributing the end desire to the agent. Applying these considerations to the notion of motivational strength we get the principle of derived strength, which states that a derived desire is as strong as its end desire. Utilizing this principle it is possible to establish an ordering of strength between any two desires. ;Deliberation is a motivational process designed to overcome some of the disadvantages associated with dynamic motivational instability---the fact that our desires and their relative strengths often depend on momentary fluctuating psychological and external circumstances, thus leading to a dynamically inconsistent pattern of behavior. The result of deliberation is the will, which is a desire with enhanced dynamic stability partly because it involves 'procedural motivation'---desires whose object concern some aspect of the process of deliberation itself. Intentions, plans, rules and values are then interpreted as particular forms of such procedural motivation