Tuesday, March 26, 2013

Currencies can be 'ultimate' or 'proximal'

In earlier postings I’ve promised some attempts at clarifying and tidying up talk about common currencies. Here is a first contribution to that project.

Generically, and of necessity vaguely because different more precise formulations appropriate to specific sciences pull in (partly) incompatible directions:

A common currency is a scalar quantity of which different options (rewards, punishments, behaviours, actions, commodities) have varying amounts. This may apply to all options, or merely to those that are in some sense “in play” for an agent at a given time.

How can currency talk be made less equivocal?

The first distinction that I need to draw is between currencies that represent some kind of order that is manifest in the choices an agent makes, and currencies that represent some aspect of the processes by which individual choices are actually produced.

Appropriating – with modest tweaks to be signaled below – some terms from a cognate area, I will call the first kind of currency ‘ultimate’ and the second ‘proximal’.

An ultimate currency is a construct in a descriptive or explanatory theory of the behavior of some agent. An ultimate currency assigns values to behaviours, or to what those behaviours achieve or (perhaps) have the function of achieving.

(We might also call this kind of currency ‘theoretical’ or ‘behavioural’ or ‘attributed’, although all of these options bring at least some unwelcome or unhelpful associations.)

Examples of ultimate currencies include various behavioural ecological versions where value is a function of fitness, and behavioural psychological versions expressed in terms of reward and reinforcement, as well as microeconomic versions that refer to utility of some kind. Considered as a set of interpretive facts, folk-psychological ascriptions of desires are also candidates for ultimate currencies.

A proximal currency, on the other hand, contributes to the process of behaviour/action selection by an agent.

(We might also call such a currency ‘causal or ‘productive’ or ‘mechanical’, although here too not all of the associations are helpful.)

Examples of proximal currencies include neuroeconomic models of the representation of subjective value in the brain.

Claims about proximal currencies usually include claims about ultimate currencies, but the converse is not generally true. The main reason that claims about proximal currencies usually include claims about ultimate currencies is that orderly choice (in some sense of ‘orderly’) is taken to follow from order in the decision making process, and so a currency in the latter should be manifest in the former. The main reason that the converse is not generally true is that at least some claims about ultimate currencies are offered in a spirit of (at least) agnosticism about causal explanation. Many micro-economists, for example, self-consciously exclude considerations of psychological implementation from their work. And some ultimate currencies (for example, among those who hold that at least some plants are capable of behavior, and that their behavior is adaptive) are described for agents that have no cognitive states at all.


  • This is a preliminary and rough statement of one important distinction. I’ll develop this distinction more fully in later postings, and also add further refinements by distinguishing sub-types of both ultimate and proximal currencies.
  • I’ll also add commented lists of examples of at least some sub-types, so that the classification takes on more substance.
  • The lists of examples (once the sub-types have been explained) might turn out to be the subjects of further evidence hooks.

Future postings:

  • Ultimate currencies: Evolutionary vs. Subjective
  • Proximal currencies: Cognitive vs. Somatic
  • List of Subjective Ultimate currencies
  • List of Cognitive Proximal currencies

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