Any reader of Rav Shagar’s sermons and essays will immediately notice that his language is a veritable pastiche of two things not found in many contemporary Jewish thinkers: Kabbalah/Hasidut and secular philosophy, Postmodernism in particular. Given how unique this feature of Shagar’s writings is, it is worth considering why he spoke and wrote that way. There seem to be a few reasons, some of which Shagar addresses in his introduction to the book of his sermons for Purim that was published in his lifetime:
It is necessary to translate the hasidic sermons to “the language of our times.” One of my goals is to attempt to shape substantial and relevant material for times and holidays that are supposed to be meaningful times of renewal and exploration, as well as to characterize each holiday in it’s own unique light. This is why I have integrated modern ideas into hasidic trains of thought, in order to translate these hasidic ideas for us and our world. […]
Further, I find in “kabbalistic language” great interpretive power and the ability to illuminate many cultural events in our time. Moreover, in many of the cultural events of our time I see the realization of the “kabbalistic vision” that speaks of the shattering of the vessels and their purification as necessary conditions for redemption, a redemption that is not simply national, but is an ontological shift in the “universal existence” (יש העולמי). (Pur Hu HaGoral, p.8)
Rav Shagar was trying to shape a new religious language, a language for talking about God and religion, for the Dati Le’umi community, with two primary components: 1) Contemporary philosophy. The Dati Le’umi (or Modern Orthodox) individual lives in the modern world, and contemporary philosophy and the social issues of postmodern society are a part of her life. They therefore ought to be a part of her religious language as well. 2) Hasidut and Kabbalah. Shagar was part of a movement that successfully introduced the study of Hasidut and Kabbalah into Dati Le’umi society, and he here gives two reasons for its importance: A) Interpretive power. The language of Hasidut and Kabbalah enabled, for Shagar, a particularly expansive and creative approach to Judaism, fitting with the creative and unbounded way these movements interpreted traditional texts. B) “Illumination of cultural events.” In addition to providing language, Kabbalah provides Shagar with a specific cosmic and historical vision that is ripe for identification with contemporary cultural events – The breakdown of all overarching narratives in postmodernity is the kabbalistic shattering of the vessels. Judaism can thus speak directly to the events of our times.
While that explains why Shagar has opted for the hasidic approach over other forms of Jewish language, it does not explain why he doesn’t simply look outside Judaism for suitable language. He’s already using secular philosophy, so why not use secular language as well? In answer to that, it is important to note that Shagar never tries speak as if he was not Jewish. He is Jewish, and that’s the starting point of his thought. He never questions this or tries to get outside it, and much of his thought philosophically argues for this kind of approach. This fits well with his interest in the thought of Franz Rosenzweig, who had an experience that concretized for him the fact that he was Jewish and that this was his starting point. He consequently became fascinated with Hebrew, in all its eras, and with the language of the traditional liturgy and the Bible. Traditional Jewish language was important to him simply because it is Jewish, and the same is true of Shagar.