Natural Rationality | decision-making in the economy of nature


Decision-making and the economy of nature

In a recent post, I presented the concept of an “economy of nature”. In this present post, I will discuss how the economy of nature provides a conceptual framework for understanding the decision-making.

I take the economy-of-nature principle to be a refinement of the natural selection principle: while it describes general features of the biosphere, it puts emphasis on the intersection between individual biographies and natural selection, and especially on decision-making. On the one hand, the decisions biological individuals make increase or decrease their fitness, and thus good decision-makers are more likely to propagate their genes. On the other hand, natural selection is likely to favor good decision-makers and to get rid of bad decision-makers. Thus biological decision-making is a central concept for models based on the economy-of-nature principle. It is not, however, equivalent to fitness maximization. It is rather one of the means by which biological agents attempt—but may fail—to maximize their fitness. They maximize their fitness when they generate copies of their own genes or through their life-history strategies, not when they catch a fish or climb a tree.
Biological agents do not choose to become sexually mature at a particular age or to invest a large part of their caloric intake in reproduction. Most of these traits are chosen by natural selection and unfold in the whole lifetime. What agents do choose, however, is to mate with this particular partner, run from this predator, eat this particular prey, etc. Even when partner preferences are fixed by natural selection, the explanation of the fact that they choose this particular one cites the individual’s own internal mechanisms. Natural selection may be able choose which type of food or partner a biological agent will seek, but not which instance. As Richard Dawkins puts it,
“[g]enes are the primary policy-makers; brains are the executives”.[1]
It is therefore more appropriate to see organisms as “adaptation executors”, not fitness-maximizers[2]—although it is likely that executing adaptations, in the appropriate environment, usually leads to fitness-maximization.
Consequently, a biological decision-maker is any agent who can control its behavior. More precisely, in order to have a genuine control over its behavior, an agent must possess control mechanisms, that is, internal structures that process sensory information and motor commands. It is meaningful to talk of individual decision-making when information-processing mechanisms are among the proximal causes of choice behavior, for otherwise it cannot be considered as a decision. A flame or a water drop does not decides to go up or down, because their “behavior” is not driven by some information it might have about its internal or external environment.
I would like to suggest here that, contrarily to common wisdom, decision-making is not specifically human, but rather a behavioral control scheme typically found in animals endowed with sensory, motor and control apparatuses, and more specifically brainy animals (craniates, arthropods and cephalopods). This continuist concept of decision-making has recently begun to be used by neurobiologists interested in the neural basis of decision-making. They labeled ‘biological decision-making’ their object of study[3]. Without explicitly defining the term, their research and methodology clearly show that they attempt to identify the structures and mechanisms that animals employ in the valuation, selection and attainment of certain goals. Glimcher[4], for instance, argues that “fundamental features of decision making are common to many species”. Risk-aversion, for instance, can be found in human and birds; given that birds and humans share a common reptilian ancestor, a risk-averse utility function might be “an efficient and evolved feature of vertebrate choice”. Thus the epithet ‘biological’ indicates that they inquire into a natural phenomenon—as opposed to the normative, ideal-agent models of rational-choice theorists—and that they analyze primarily its biological substrate, not its logico-linguistic structure. Belief-desire-intention reasoning would be then not the core of decision-making, but only a uniquely human implentation of it. In a future post, I will discuss how neuroscience and ethology supports this continuist picture of decision-making.

Notes and References
  • [1] (Dawkins, 1976, p. 59)
  • [2] (Tooby & Cosmides, 2005, p. 14).
  • [3] (P. W. Glimcher, 2003; P. R. Montague et al., 2006; P. Read Montague & Quartz, 1999) see also (Gintis, 2007)for a similar construal of decision-making.
  • [4] (Paul W. Glimcher & Rustichini, 2004)

  • Dawkins, R. (1976). The selfish gene. New York: Oxford University Press.
  • Gintis, H. (2007). A framework for the unification of the behavioral sciences. Behavioral and Brain Sciences, 30(01), 1-16.
  • Glimcher, P. W. (2003). The neurobiology of visual-saccadic decision making. Annu Rev Neurosci, 26, 133-179.
  • Glimcher, P. W., & Rustichini, A. (2004). Neuroeconomics: The Consilience of Brain and Decision. Science, 306(5695), 447-452.
  • Montague, P. R., King-Casas, B., & Cohen, J. D. (2006). Imaging valuation models in human choice. Annu Rev Neurosci, 29, 417-448.
  • Montague, P. R., & Quartz, S. R. (1999). Computational approaches to neural reward and development. Mental Retardation and Developmental Disabilities Research Reviews, 5(1), 86-99.
  • Tooby, J., & Cosmides, L. (2005). Conceptual foundations of evolutionary psychology. In D. M. Buss (Ed.), The handbook of evolutionary psychology (pp. 5-67). Hoboken, NJ: Wiley.