This chapter introduces the reader to the second part of Kahneman’s book. He calls this part Heuristics and Biases, which highlights the major components of selective or subjective thinking. This chapter outlines the factors under which System 2 operates, particularly formulates a hypothesis based on known factors. While System 1 effortlessly identifies causal connections between events, System 2 critically evaluates a given situation. The author utilizes several illustrations that enable the reader to see the impact of details in reasoning. He centers his argument on the assumption that large samples will tend to be more concise, hence yield fewer conclusions that small samples. Kahneman introduces the law of small numbers, which asserts that minor details matter as much as a large amount of information does.