Ineffability – that which cannot be explained in words – lies at the heart of the Christian mystical tradition. This is the first book to engage with the concept of ineffability within contemporary philosophy of religion and provides a starting point for further scholarly debate.

Can art, religion, or philosophy afford ineffable insights? If so, what are they? The idea of ineffability has puzzled philosophers from Laozi to Wittgenstein. In Ineffability and its Metaphysics: The Unspeakable in Art, Religion and Philosophy, Silvia Jonas examines different ways of thinking about what ineffable insights might involve metaphysically, and shows which of these are in fact incoherent. Jonas discusses the concepts of ineffable properties and objects, ineffable propositions, ineffable content, and ineffable knowledge, examining the metaphysical pitfalls involved in these concepts. Ultimately, she defends the idea that ineffable insights as found in aesthetic, religious, and philosophical contexts are best understood in terms of self-acquaintance, a particular kind of non-propositional knowledge. Ineffability as a philosophical topic is as old as the history of philosophy itself, but contributions to the exploration of ineffability have been sparse. The theory developed by Jonas makes the concept tangible and usable in many different philosophical contexts.

How is religious experience to be identified, described, analyzed and explained? Is it independent of concepts, beliefs, and practices? How can we account for its authority? Under what conditions might a person identify his or her experience as religious? Wayne Proudfoot shows that concepts, beliefs, and linguistic practices are presupposed by the rules governing this identification of an experience as religious. Some of these characteristics can be understood by attending to the conditions of experience, among which are beliefs about how experience is to be explained.

The notion of ineffability (of that which is, in principle, resistant to conceptual formulation and therefore literal linguistic articulation) has been largely ignored by philosophers. The notion is clearly a central one in the Christian mystical tradition and in more recent apophatic theological developments. Mid-twentieth-century philosophical discussions of mysticism invoked the idea and a number of phenomenologists share a sense that the meaningful human world is answerable to some 'background' that is inarticulable and mysterious. But, despite this, the logical implications of the notion of ineffability for religious experience, language and practice have not been explicitly and systematically thought through. This thesis, restricted to a dual focus on twentieth-century and contemporary philosophy and on the Christian religion, attempts to address this neglect. After reviewing the philosophical, and some theological, literature on the notion of ineffability in religion, this thesis identifies a philosophical tension between the notions of 'ineffability' and 'answerability', between the idea that the ineffable is beyond conceptualization and that some kind of experience, language or practice connected with it is required if the notion is to be meaningfully invoked, let alone (as in a religious context) serve as the measure for the meaning of the human world. In this connexion, the meaning of the word 'God' is interpreted as a reference to the concept of ineffability. A recent philosophical defence of the concept is endorsed which, rooted in existential phenomenology and Heidegger's later philosophy, resolves this tension. The detail of theological attempts, by Paul Tillich and John Macquarrie, to accommodate this line of thought as directly inherited from the phenomenologists (especially Heidegger) is examined and criticized, as, eventually, is a more promising theological possibility represented by the neglected philosophy of Karl Jaspers. The rational status of existential phenomenology (its relation to discourse conditioned by the subject-object dichotomy) is examined more closely in the light of the latter criticism. It is concluded that phenomenology's specifically philosophical way of evoking the ineffable is necessarily that of a rationally-based dialectic. The final chapter points to spheres outside philosophy, aesthetic and ritual, which cultivate the experience of the ineffable without such dialectic. It offers an 'aesthetic account of ritual meaning' and concludes by showing how the Eucharistic rite can be philosophically understood as a vehicle for religious experience and expression - the evocation and invocation of the ineffable God.

Arguing against the notion that religious experience is ineffable, while advocating the view that it can provide evidence of God's existence, this text contends that social science and nonreligious explanations of religious belief and experience do not cancel out the force of the experience.

Harvard psychologist and philosopher William James' The Varieties of Religious Experience: A Study in Human Nature explores the nature of religion and, in James' observation, its divorce from science when studied academically. After publication in 1902 it quickly became a canonical text of philosophy and psychology, remaining in print through the entire century. "Scientific theories are organically conditioned just as much as religious emotions are; and if we only knew the facts intimately enough, we should doubtless see 'the liver' determining the dicta of the sturdy atheist as decisively as it does those of the Methodist under conviction anxious about his soul. When it alters in one way the blood that percolates it, we get the Methodist, when in another way, we get the atheist form of mind."

Augustine's vision at Ostia is one of the most influential accounts of mystical experience in the Western tradition, and a subject of persistent interest to Christians, philosophers and historians. This book explores Augustine's account of his experience as set down in the Confessions and considers his mysticism in relation to his classical Platonist philosophy. John Peter Kenney argues that while the Christian contemplative mysticism created by Augustine is in many ways founded on Platonic thought, Platonism ultimately fails Augustine in that it cannot retain the truths that it anticipates. The Confessions offer a response to this impasse by generating two critical ideas in medieval and modern religious thought: firstly, the conception of contemplation as a purely epistemic event, in contrast to classical Platonism; secondly, the tenet that salvation is absolutely distinct from enlightenment.