A critic of the work of Daniel Kahneman and Amos Tversky, he argues that heuristics should not calculated risks gerd gigerenzer calcualted to conceive of human thinking as riddled with irrational cognitive biases, but rather to conceive rationality as an adaptive tool that is not identica Gerd Gigerenzer is a German psychologist who has studied the use of bounded rationality and heuristics in decision making, especially in medicine.