Proscriptive planning exercises are critical to and generally accepted as integral to health planning at varying scales. These require specific instruments designed to predict future actions on the basis of present knowledge. At the macro-level of health economics, for example, a number of future-oriented Quality of Life Instruments (QL) are commonly employed. At the level of individual decision making, on the other hand, Advance Directives (AD's) are advanced as a means by which healthy individuals can assure their wishes will be carried out if at some future point they are incapacitated. As proscriptive tools, both instrument classes appear to share an axiomatic set whose individual parts have not been rigorously considered. This paper attempts to first identify and then consider a set of five axioms underlying future oriented health planning instruments. These axioms are then critiqued using data from a pre-test survey designed specifically to address their assumptions. Results appear to challenge the validity of the axioms underlying the proscriptive planning instruments.