In Greek an ἀπολογία is a speech for the defense, but thanks to the compositions of Plato and Xenophon on behalf of their master Socrates, the term passed into philosophy without losing its forensic associations. Eusebius of Caesarea was the first to apply the term “apologetic” to Christian literature (Eus. Hist. eccl. 4.3; 4.13 etc.), but the works that are commonly brought under this rubric by modern scholars fall into four overlapping categories:

1.  vindicator…