Value involves a triadic relation between a person, a thing and an end desired by a person and obtainable by the thing. Let us consider this relation.
The thing is ordained to the end and we consider it valuable in so far as it is ordained to that end. As we have spoken of before, when this ordination, orientation of finality of the thing is intrinsic, that is involves some power of the thing to obtain the end, we speak of this as “intrinsic” value. Whereas when the finality of the thing to the end is extrinsic, we may call this “conventional” value.
Here we should recognize that if the thing is ordered in no way to the end, it is considered worthless, that is having no value qua this end. An injection of insulin is valuable qua health of a person with diabetes, but is worthless qua light for a room, writing my thoughts, or a host of other ends.
Next and perhaps obviously, the value concerns some end desired by a person. We might in this respect consider value as good qua rational. The Philosopher distinguishes between luck and fortune in that luck is when a good event occurs by chance, but fortune good or bad occurs by chance to a rational agent. Here we may make a similar distinction between good as such and value as good to or for a rational agent. When we specify economic value as we are exploring here, we are speaking of value for a rational agent regarding an external object to be used, to distinguish this from the value of our internal powers and efficacy.
The Angelic Doctor teaches that a thing is valued in that it is useful to man. This usefulness to man presuppose some end that man is attempting to achieve. Hence, a thing is worthless if it does not achieve an end desired by man. A injection of insulin is valuable to a diabetic, but not to a non-diabetic, because he has no need of it.
Finally, there is the relation of use between the person and the thing. This is a relation concerning the ability of the person to make use of the thing to achieve the end. Uranium is extremely valuable in its power to produce heat and energy, which are ends men have often desired. However, it is worthless to men who do not have the means to make use of it.
Notice that in this we have spoken of the three termini together in order to describe value. It is insufficient for value to be founded in any pair of the relations or even all three together. Value is or is grounded in the traidic or three-fold relation between person, thing and end.