[P]hilisophical naturalism could never serve as a complete, coherent, or even provisionally plausible picture of reality as a whole. . . The question of existence is real, comprehensible, and unavoidable, and yet it lies beyond the power of naturalism to answer it, or even to ask it. (p95)
To be clear here: not only has physics not yet arrived at an answer to this question, it never can. All physical events - all physical causes, all physical constituents of reality - are embraced within the history of nature, which is to say the history of what already has existence. The question of existence, however, concerns the very possibility of such a history, and the very expectation that the sciences could possibly have anything to say on the matter is and example of what might be called the "pleonastic fallacy"; that is, the belief that an absolute qualitative difference can be over come by a successive accumulation of extremely small and entirely relative quantitative steps. This is arguably the besetting mistake of all naturalist thinking, as it happens, in practically every sphere. (p98)
At some point, then, at the source of all sources and the origin of all origins, the contingent must rest upon the absolute. One will not understand this line of reasoning properly, however, unless one recognizes [sic] that it is not concerned with the question of the temporal origin of the universe; it would make no difference for the argument whatsoever if it should turn out that the universe has existed forever and will go on existing eternally, without beginning or end, or that it belongs to some beginningless and endless succession of universes. (102)
. . . the cause of being is not some mechanical first instance of physical eventuality that, having discharged its part, may depart the stage; rather, it is the unconditional reality underlying all conditioned things in every instant. (104)
Hart is at pains, over several pages, to make the often overlooked distinction between cosmology and ontology clear. I think it is a helpful point and certainly relevant to discussions about the relationship between science and theology, i.e. any cosmological claims made by religion are at risk of the being overturned by the advances of science, but ontological claims are of a different order. And of course this is not just about justifying religious belief in the face of atheist attacks but about requiring an answer from the atheist as to how they explain existence in the first place. All good. Hart also makes a slightly more overreaching claim in the same vein which I might try and explain in another post.
Let me know what you think, :-)