In this chapter we discuss matters of syntax and axiomatics. All material is propositional, and will be so until Chapter 10.

Justification logics are closely related to modal logics, so we start briefly with them in order to fix the basic notation. And just as normal modal logics all extend a single simplest example, K, all justification logics extend a single simplest example, J₀. We will begin our discussion with modal logics, then we will discuss the justification logic J0 in detail, and finally we will extend things to the most common and best- known justification logics. A much broader family of justification logics will be discussed in Chapter 8.

2.1