This chapter shows a link between the irrationality and unpredictability of law and the underlying values embedded in the formative process of Iberic culture. Based on concepts by Max Weber and Buarque de Holanda, it suggests that the current lack of respect towards supreme courts’ precedents derives from a culture characterized by personalism and patrimonialism. The aversion to impersonality and rationality, a feature of agents that seek to turn the public sphere into a private one and to run away from legislation’s generality, results in a culture that does not adequately care about the predictability of the law and equality in judicial decisions.