Two Systems of Reasoning (System 1 and System 2)

THE EMPIRICAL CASE FOR TWO SYSTEMS OF REASONING

The stimulation from a classic paper in the heuristics and biases tradition does not come only from the insights provided into processes of judgment and decision making; it also comes from anxiety, from the tension introduced between immediate intuition and more measured rational belief. Clearly, there is a limit to how much one’s interest is piqued by reading about other people’s mistakes. It is our own mistakes, and the insights they bring, that are so arresting and compelling. The tension is revealing because it reflects a gap within our own heads between, on one hand, our intuitions and, on the other hand, those of our beliefs that we consider rational. The classic demonstrations often suggest two minds at work: one following the “natural assessment methods” like representativeness and availability; and the other working to form coherent, justifiable sets of beliefs and plans of action. As Tversky and Kahneman have repeatedly shown, the two minds do not always agree.

The distinction between these two minds can be construed in terms of one of the central puzzles in experimental psychology – whether people are best conceived as parallel processors of information who operate along diffuse associative links, or as analysts who operate by deliberate and sequential manipulation of internal representations. Do we draw inferences through a network of learned associative pathways or by applying some kind of psycho-logic that manipulates symbolic tokens in a rule-governed manner? The debate has raged (again) in cognitive psychology for well over a decade now. It pits those who prefer models of mental phenomena to be built out of networks of associative devices that pass activation around in parallel and distributed form (the way brains probably function) against those who prefer models built out of formal languages in which symbols are composed into sentences that are processed sequentially (the way computers function).

An obvious solution to the conundrum is to conceive of the mind both ways: to argue that the mind has dual aspects, one of which conforms to the associationistic view and one of which conforms to the analytic, sequential view. Such a dichotomy has its appeal: Associative thought feels as though it arises from a different cognitive mechanism than does deliberate, analytical reasoning. Sometimes conclusions simply appear at some level of awareness, as if our minds go off, do some work, and then come back with a result, and sometimes coming to a conclusion requires doing the work yourself, making an effort to construct a chain of reasoning. This distinction has not been missed by philosophers or psychologists; it can be traced back to Aristotle and has been discussed, for example, by James (1890), Piaget (1926), Vygotsky (1934/1987), Neisser (1963), and Johnson-Laird (1983) among others.

This distinction is implicit in the notion of “transparency” (Tversky & Kahneman, 1983). A manipulation that reduces bias by making an extensional probabilistic or logical relation transparent is in essence providing a representation that affords rule-based inference, allowing people to go beyond associative reasoning. But the presence of two systems for judgment and choice can make life difficult. Cases of inconsistency between rules and associations are one of the primary sources of conflict both within and between individuals. Decisions that we make every day are made more difficult by opposing recommendations from the two systems. This sort of conflict dominates much of choice behavior. Consumer choices are often between products that conjure up strong associations due to effective advertising or market longevity and products whose value can be justified analytically. Choosing between brand names, with which we have had long experience, and generic products, which sometimes have identical ingredients and a lower price, has this character. This type of conflict is even more palpable when we consider political options. A politician may seem attractive when expressing our values or promising to solve our problems, but analysis may suggest that enacting the candidate’s policies is impractical, immoral, or both. More generally, people can be torn between descriptions that they “resonate” to and descriptions that they find analytically more accurate.