 Modal logics are particularly well suited to study a wide range of philosophical concepts, including rational beliefs, obligations, knowledge, intentions, desires, evidence and preferences, among many others. Such an analysis provides us with the key insights of the basic building blocks and principles that regulate different behaviors, which is important in a wide range of academic disciplines including Artificial Intelligence, Psychology, Social Science and even Physics. The concepts we look at have specific context-dependent features, which indicates that they can be best studied using models that can express different modes of truth (e.g., both global and local truth). But as Scott’s (1970) quote above suggests, there is something missing when such philosophical concepts are studied in isolation. A big part of what defines a concept lies in the way it interacts with others. For instance, rational beliefs are expected to rely on proper arguments, justifications or evidence; disjunctions may not behave as they do in natural language in the context of obligations; knowledge is better understood when looking for the actions that modify it; intentions may be understood as derived from desires and beliefs. What is required for this study are logical systems with more than one modal operator, commonly known as multi-modal logics, describing not only the isolated properties of the individual concepts, but also the way they relate to one another. Indeed, multi-modal logics have been designed for a wide range of applications, including reasoning about time, space, knowledge, beliefs, intentions, desires, obligations, actions such as public and private communication, observations, measurements, moves in a game and others.