Disclaimer: I am a complete layman in psychology, with no education in the field whatsoever. This question was prompted by my reading Kahneman's "Thinking Fast and Slow", in which he discusses the model of System 1 and System 2 extensively.
I thought many of the cognitive biases and other psychological effects were fascinating to read about, and I really enjoyed it. But every time he brought the "two systems" into the discussion of a particular cognitive bias (such as the affect heuristic or hindsight bias), it felt like he was using it as a post hoc explanation of how the effect could be described by certain characteristics of the two systems. It was never clear to me how you can show that the dual process implies the existence of the discussed effect.
I think he did a far better job showing how certain psychological effects result from prospect theory. It's easy to show, for example, how prospect theory implies the endowment effect, as shown in the given link. Even though knowledge of the endowment effect existed before prospect theory, it's easy to see how the endowment effect could have been predicted by prospect theory. You can even prove that it would exist, given the utility function of prospect theory and the right axioms.
But I'm confused about how you can do the same with dual process theory, and the cognitive biases that it supposedly explains. How can you use dual process theory to predict the existence of a cognitive bias? Are there examples of cognitive biases that were, or can be explicitly predicted using DPT?
If this is just a poorly framed question--if predicting cognitive biases is not one of the purposes of the theory--then what is the purpose of dual process theory?
EDIT: I want to make a few clarifications here. My concern is neither with the predictive success of DPT - or other theories to which I compare it - nor is it with whether the things that DPT can predict have already been discovered before DPT. The example I used - prospect theory, and its "prediction" of the endowment effect - is both retroactive (the effect was known before the theory), and according to the answer by Fizz, has questionable predictive verification. However, the manner by which you can use the theory to make the prediction is quite clear. If we assume the value curve given by prospect theory, and the claim of prospect theory that a person's perceived value of a gain or loss is relative to their current position rather than absolutely dependent on the final state, then it follows logically that an individual's perceived gain in value for acquiring something is lower than their perceived loss in value for losing the same thing. This can be answered in theory, on pen and paper, given the framing of the scenario and the axioms of prospect theory.
With dual process theory I want to understand:
- what kind of predictions it can make about human behavior
- how to make those predictions using the theory
Since this is seemingly a very celebrated modern theory of human behavior, I just want to know how it's used. I don't mind if every known consequence of dual process theory was discovered before the theory, nor do I mind if the method is not as rigorous as that of a physics theory.