# Gigerenzer on system one and system two

If you have read Daniel Kahneman’s Thinking, Fast and Slow, you will be familiar with the concepts of System One and System Two. Gerd Gigerenzer is not a fan of the dichotomy, with the below passage from an interesting interview by Justin Fox (the one over N heuristic Gigerenzer refers to is the heuristic to invest your money equally across your N options):

What is system one and system two? It’s a list of dichotomies. Heuristic versus calculated rationality, unconscious versus conscious, error-prone versus always right, and so on. Usually, science starts with these vague dichotomies and works out a precise model. This is the only case I know where one progresses in the other direction. We have had, and still have, precise models of heuristics, like one over N. And at the same time, we have precise models for so-called rational decision making, which are quite different: Bayesian, Neyman-Pearson, and so on. What the system one, system two story does, it lumps all of these things into two black boxes, and it’s happy just saying it’s system one, it’s system two. It can predict nothing. It can explain after the fact almost everything. I do not consider this progress.

The alignment of heuristic and unconscious is not true. Every heuristic can be used consciously or unconsciously. The alignment between heuristic and error-prone is also not true. So, what we need is to go back to precise models and ask ourselves, when is one over N a good idea, and when not? System one, system two doesn’t even ask this. It assumes that heuristics are always bad, or always second best.

## 2 thoughts on “Gigerenzer on system one and system two”

1. It really is a pity that Gerd Gigerenzer feels it is necessary to erect straw men like ‘System one, system two […] assumes that heuristics are always bad, or always second best’.

2. Steve says:

And anyone who’s read Kahneman’s book will see him repeatedly say that system one and system two don’t really exist. He says he’s doing this because he knows that psychologically, we like to hear about agents. You can easily enough use system one as a shorthand for the myriad of mental processes (or modules, but I’m sure that phrase has fallen out of fashion) that specialise in various functions, and system two for the higher order functions of areas like the prefrontal cortex. I agree with Koenfucius – its a straw man that Kahneman pre-empts.