This is a rather technical but accessible case study of the split between "continental" and "analytic" philosophy. Friedman focuses on 3 disparate figures; the analytic philosopher Rudolph Carnap, the seminal continental philosopher Martin Heidegger, and the the influential neo-Kantian philosopher and historian Ernst Cassirer. As Friedman demonstrates, these men had a common intellectual heritage in the Neo-Kantian revival that occurred at the end of 19th century. This heritage provided something of a common vocabulary and also resulted in the identification of common philosophic problems, notably aspects of dualities in Kants' epistemology. The specific roles of logic, mathematics, and scientific thought as forms of knowledge were also points of contention. Friedman provides a concise but detailed discussion of the Neo-Kantian background, emphasizing its diversity, with Heidegger emerging from one strand of the Neo-Kantian background, and Cassirer as he final flower of another strand. These 3 philosophers are presented as responding to the common set of problems in Neo-Kantianism in markedly different ways. Carnap pursues a reconstruction of epistemology inspired by newer developments in mathematical logic. Heidegger undertakes perhaps the most radical transformation with an effort to strike out in a new direction which appears (to me, at any rate) as a wholesale rejection of the previously crucial role of logic and scientific knowledge. Both of these thinkers drew on important new developments in philosophy; Carnap on Frege and Heidegger on Husserl's phenomenology. Friedman has a very sympathetic discussion of Cassirer's thought, which he sees as something of an effort to respond to concerns that motivated both Carnap and Heidegger, resulting in a body of thought that occupies something of middle way between Carnap and Heidegger.
Friedman, then, stresses the common heritage of "analytic" and "continental" philosophy and suggests that the split is not as great as conventionally portrayed. He suggests also that the split is partly the contingent result of the success of Nazism. Carnap, Cassirer, and most other analytically oriented philosophers had to leave Germany, eiher because of ethnicity or because of their political views. Heidegger, who later embraced Nazism, was left as the only great philosopher in Germany, and possibly in continental Europe. Friedman points out that Carnap, Cassirer, and Heidegger had very collegial relations prior to the Nazi seizure of power. The implication is that preservation of routine academic life in Germany would have resulted in more interaction and cross-fertilization. I'm not sure that Friedman is entirely convincing on this point. Its clear from his account that Carnap and Heidegger produced radically different and quite irreconcilable responses to what appears to have been a set of common problems. Friedman argues well for Cassirer's distinctive contribution but Cassirer's continued emphasis on the importance of science, mathematics, and logic places him much closer to Carnap in some crucial respects. It really appears that despite a common heritage, there really was a great split.
It also has to be commented that the claim of contintental philosophy to be more oriented to human concerns, as opposed to the technical preoccupations of analytic philosophy, is belied by the fact that in fundamental matters of ethics, it was people like Carnap and Cassirer who got it right.