O. Bradley Bassler, Kant, Shelley and the Visionary Critique of Metaphysics. Cham: Palgrave Macmillan, 2018. Pp. 262. $79.99. ISBN 9783319772912.

Bassler explores how Immanuel Kant's thinking on the metaphysics and epistemology of sense experience opens philosophical and poetical doors to what he calls the parafinite. Unlike earlier metaphysical theories, distinctions between the finite and the infinite are not easily drawn when the mind synthetically unifies perceptual objects that remain radically indeterminate. Bassler traces a historical genealogy of post-Kantian extrapolations of this notion to mark out a new area in philosophy he calls paraphysics, where attempts to define the infinite in terms of the absolute are consistently outpaced by the indeterminate, yet constitutive nature of sense experience. Bassler considers such thinking to be a visionary critique of Kant's own more strict separation of the theoretical from the practical realms.

In the final section (which takes up about a quarter of the book) Bassler stages an encounter between Kant and Shelley which shows Shelley loosening Kant's prophylactic (34) separation of the noumenal and the phenomenal. The agon between Kant and Shelley problematises one reading of Kantian sublimity in Romantic poetry which stresses the role of the imagination to limit and contain the overbearing power of reason. This notion is represented through consideration of the work of Northrop Frye, Earl Wasserman and Harold Bloom. These are the only literary critical sources considered, as the aim of this book is admittedly rather one-sided - to see what Shelley can do for critical philosophy, rather than the other way around. Despite the overall success of this endeavour, one feels that the work of scholars like Ross Wilson, who have worked extensively on Shelley and post-Kantian thought, might have been productively addressed.

The earlier sections systematically work through various post-Kantian thinkers' responses to the question of whether the imagination is part of a faculty psychology which is ultimately beyond the experience of space and time or a way of negotiating them. The first two chapters analyse Kant's ideas in depth, discussing distinctions between the 'relative' and the 'absolute' parafinite. Kant's sublime is not relative to something else, but to everything else, so is absolutely, rather than relatively, parafinite. Chapter three concentrates on Leibniz's concept of sufficient reason, disambiguating the idea of what is requisite from what is necessary. When what is requisite is seen as courting the unknown and the indefinite then Kant's notion of 'self-positioning' (17) - the mind's locating of itself in external space - comes into its own. With a philosophical project more akin to Shelley's own, Peirce is shown to press on Kant's notion of the immediacy of experience, arguing that symbolic connections made between concepts like morality and freedom are implacably mediate, not indirect.

Chapter four continues this line of thought to explore continuities and discontinuities between Kant and Husserl, arguing that Husserl's ideas harbour a hidden commitment to the indefinite. The intentionality attributed to consciousness by Husserl may turn out to be a kind of intuitive process that, like Kant's phenomenal realm is regulative, rather than fully constitutive. Brouwer, Hilbert, Tarski, Wittgenstein and Frege are also discussed here. Chapter five further explores the idea presented in the first two chapters that Kant's critical philosophy is 'layered' (21) by various levels of possible figurative and symbolic experience. This, Bassler argues, can complicate Kant's own split between the theoretical and the practical in ever more pragmatic ways.

Chapter six presents analyses of Shelley's poems and his unconscious grappling with the absolute parafinite, via comparison to Milton's and Blake's more obviously theological thought-patterns. Particularly in The Triumph of Life, Bassler makes astute arguments which differentiate between 'rhetorical figuration' and what he calls Shelley's 'locative poetics', (202) which engage with a 'real physics of motion' (199) rather than with what has become familiar to literary scholars as the deconstructive interchangeability of figures. Bassler also presents the intriguing idea that Shelley did not address the parafinite directly in his work because he was psychologically constrained by an 'epistemological perfectionism' (191). He wanted to plumb the depths of the indefinite and construct a totalised vision of creation and knowledge in the manner of Milton and Blake. But his poetry strains in another direction: particularly through the figure of Demogorgon (Prometheus Unbound), and in the rushing chariot of The Triumph of Life, Bassler argues that Shelley's poetry attests that the indefinite by definition cannot be conceptually delimited.

Having been allowed to test the limits of a philosophical tradition based on logical positivism Shelley's work remains a 'poetic pedigree' (181) for the kind of post-Kantian thinking Bassler has identified, rather than a mode of philosophical knowledge in its own right. Nevertheless, it is a fascinating and insightful argument that literature might help critical philosophy out of its current impasse by showing it its own historical conditions of possibility: allowing it to reflect upon its own modes of self-representation, as they have been constructed by the genealogies to which it is indebted.

Merrilees Roberts, Queen Mary, University of London