The Logic of Framing: The Framing Effect as a Non-Monotonic Decision Process of Path Dependence Michiel den Haan Abstract: People's perception can be influenced by framing a message in different ways. For example, decision makers are often favourably disposed towards a medical treatment with a 60% success rate, but less often to one with a 40% failure rate. This suggests that human judgement or decision making is not merely concerned with the content of the message at stake, but also with the way in which this content is presented or 'framed'. This observation is at odds with standard theories of decision making, which prescribe that human judgement should be invariant under different descriptions of the same fact(s). In this thesis, I explore what framing is, how it makes itself manifest and how the underlying process of human decision making functions. I argue that this decision process is best to be characterised as a non-monotonic process of path dependence, and I present a formal model to make this idea more precise. This model has several advantages over existing models. It is able to provide an elaborate account of framing that is descriptively accurate, more uniform and has a larger scope than existing accounts. Furthermore, it allows for a thoughtful approach to the relationship between the framing effect and human rationality.