As researchers try to accumulate knowledge in artificial intelligence (AI), towards developing better models and artefacts to embody complex decision making processes based on the characteristics of human decision making, we are reminded that at the beginning of this whole endeavour our intellectual ancestors – Newell and Simon (1972) for instance, had warned that a comprehensive understanding of human decision making would be required if AI was to yield substantial benefits. In wondering whether this has been achieved, we trace back the accumulated knowledge in the area of human decision making from the work of Savage through to that of Simon and we critically assess whether we have reached the required critical mass in our understanding of human decisions. Such knowledge development is a requisite benchmark to measure the progress of research in artificial intelligence, as illustrated by the other chapters in this book.