Smith's position is that big bang cosmology and quantum cosmology confirm atheism or at least the belief that God probably does not exist. Quentin Smith is more interested in answering the question about why the universe exists than he is in the question, does God exist or is atheism true? And he regards the hypothesis that God created the big bang or a quantum universe merely as one of several hypotheses about the best way to understand big bang cosmology and quantum cosmology. His philosophy of time overlaps with his philosophy of language, for his main position is that the best explanation of why language has tenses is that pastness, presentness and future are objective features universe. Quentin Smith has published four books on time, two books on atheism and the philosophy of religion, one book on physical cosmology, one book on existentialism and phenomenology (on his "metaphysics of feeling"), and one book on the philosophy of mind. Also, he has published approximately 120 articles in scholarly academic journals and edited books.  Quentin Smith?s other publications on other topics are can be found in his vita.

 Quentin Smith's work is also studied, and written about, in fields other than philosophy. For the most part, these fields are linguistics, physics and poetry. Smith's article "The Multiple Uses of Indexicals" has been one of the most influential contemporary papers in the field of linguistics, since its first publication in 1989. Smith's writings on physics, specifically on classical big bang cosmology, semi-classical big bang cosmology and quantum gravity cosmology have been studied and discussed by physicists who work in this area. Stephen Hawking, James Hartle, Roger Penrose, Andrei Linde, Arthur Vilenkin, and Christopher Isham are some of the physicists who work, in private or in print, with Smith in this area. Quentin Smith is also known among physicists as the originator, in 1990, of natural selection cosmology, i.e., the theory that there are many universes, each of whose big bang is a black hole in another universe.

This theory was developed in Smith's "A Natural Explanation of the Existence and Laws of Our Universe" (1990), and his development of it, to include quantum gravity, appears in his "The Black Hole Origin Theory of the Universe and Quantum Gravity" (2000; 2004). (The physicist Lee Smolin independently rediscovered this theory in 1992 and in his 1997 book The Life of the Cosmos, but the equations that form the necessary mathematical heart of this theory can only be found in Smith's two articles.) Quentin Smith's poetry has been published by such national poetry journals as The Shore Review, Wind, and The Kentucky Poetry Review since the 1970s and he acceded to the request to have some of his poems published in a forthcoming book consisting only of his poetry, entitled Echoes from the Edge of the Universe: A Book of Poems.