One of the virtues of this edited collection is the diversity contained within it. There is diversity to be found in the uses made of Wittgenstein's writings, reflecting the diversity of ways of understanding religion found in Wittgenstein's work. Andrejč, in his introduction (3), suggests that there are four dominant ways in which Wittgenstein depicts religion: the nonsensicalist, existentialist, grammaticalist and instinctivist conceptions of religion. In his early work Wittgenstein claimed that religious propositions were nonsensical (the nonsensicalist conception of religion). Wittgenstein claimed that ‘propositions of natural science’ are ‘what can be said’ (Ludwig Wittgenstein, Tractatus Logico-Philosophicus, tr. D. F. Pears and B. F. McGuinness (London: Routledge, 1961), 6.53), but even if we have all possible scientific claims laid out before us, we have not touched upon ‘the problems of life’ (6.52), including problems concerning God (6.432) and the immortality of the soul (6.4312). Vörös and Štrajn's chapter uses a Wittgensteinian nonsensicalist approach to interreligious dialogue which places activity at its centre, as a way of resolving existential problems. In both Wittgenstein's early and later work we can find an existentialist conception of religion, in which Wittgenstein emphasises the importance of experience and volition for religion. For example, in the ‘Lecture on Ethics’ Wittgenstein talks about feelings of ‘wonder at the existence of the world’ and of ‘safety’ as being central to religion and ethics (Ludwig Wittgenstein, Philosophical Occasions, ed. James Klagge and Alfred Nordmann (Indianapolis: Hackett, 1993), 41–42) and in a remark from 1950, Wittgenstein suggests that ‘sufferings of various sorts’ can lead a person to belief in God: ‘Experiences, thoughts, – life can force this concept on us’ (Ludwig Wittgenstein, Culture and Value, 2nd edn, ed. G. H. von Wright (Oxford: Blackwell, 1998), 97e). Venturinha's chapter, on Wittgenstein's understanding of religious belief, highlights existentialist passages from Wittgenstein's ‘Lecture on Ethics’ and connects them with John Henry Newman's influence on Wittgenstein. In Wittgenstein's later work we can find grammaticalist and instinctivist conceptions of religion. The grammaticalist says that central religious assertions are best understood as being grammatical remarks that tell us how to use religious terms in everyday religious discourse. In the Philosophical Investigations Wittgenstein says that ‘Grammar tells us what kind of object anything is’ and in parentheses afterwards describes ‘Theology as grammar’ (Ludwig Wittgenstein, Philosophical Investigations, rev. 4th edn, tr. G. E. M. Anscombe, P. M. S. Hacker, and Joachim Schulte (Oxford: Wiley-Blackwell, 2009), §373). In the last remark of Zettel he says ‘“You can't hear God speak to someone else, you can hear him only if you are being addressed”. That is a grammatical remark’ (Ludwig Wittgenstein, Zettel, ed. G. E. M. Anscombe and G. H. von Wright, tr. G. E. M. Anscombe (Oxford: Basil Blackwell, 1967), §717). It is not merely a contingent, empirical matter that you cannot hear God speaking to other people. It is not as though if you had better hearing you might listen in on God speaking to others. If you understand what ‘God’ means then you understand that God can only be heard by the person addressed. Rhiannon Grant's chapter in the volume takes a broadly grammaticalist approach to religion and takes up George Lindbeck's analogy between religion and language as a way of understanding people belonging to more than one religion. The instinctivist conception of religion emphasizes the role of instincts or ‘primitive’ reactions in religion, in contrast to intellectualist accounts which suggest that religious beliefs are hypotheses or that they are aimed at bringing about changes in the world through recognition of the causal efficacy of religious practices (a kind of proto-science). The locus classicus for this kind of interpretation of religion in Wittgenstein's work is his ‘Remarks on Frazer's Golden Bough’ (published in Philosophical Occasions), but you can find the anti-intellectualist tendency in many other places in Wittgenstein's work. For example, in a remark published in Culture and Value Wittgenstein says that ‘[t]he origin and primitive form of the language game is a reaction; only from this can more complicated forms grow. Language – I want to say – is a refinement “in the beginning was the deed”’ (36e). Randy Ramal's chapter, about radical pluralism (i.e. ‘the irreducibility of people's diverse discourses and concepts into a set of common meanings and truths’, 135), makes use of the instinctivist conception of religion as a way of coming to understand the multiplicity of religious traditions and thereby facilitating dialogue between religious people with different grammatical frameworks. Paul Cortois's chapter also uses an instinctivist conception of religion in discussing the role of reverence in religion and the role of hospitality in overcoming exclusivist tendencies in religious life. We could add that in Wittgenstein's later work we also find the tools for thinking about religion in terms of hinge-commitments (i.e. in terms of certainties that are exempt from doubt (Ludwig Wittgenstein, On Certainty, ed. G. E. M. Anscombe and G. H. von Wright (New York: Harper & Row, 1972), §341), which must ‘stay put’ (§343) if we are to investigate claims, justify them, or introduce reasons for doubting them) and two of the chapters in this volume, von Stosch's (ch. 4) and Bennett-Hunter's (ch. 8), discuss the possibility of thinking about religion in terms of hinges.

Of course, we should not think of any of these conceptions as an overarching theory meant to explain all of religion. Wittgenstein himself famously did not think that philosophy was a theoretical discipline at all (and so, philosophy of religion in particular is not theoretical, according to Wittgenstein). In a remark in the Philosophical Investigations Wittgenstein says that ‘It was correct that our considerations must not be scientific ones . . . And we may not advance any kind of theory. There must not be anything hypothetical in our considerations. All explanation must disappear, and description alone must take its place’ (§109). Moreover, there is diversity within the utterances, writings, and practices that we call ‘religious’ such that we cannot capture what counts as religion with a neat definition in terms of necessary and sufficient conditions. New candidates for religious status come into existence all the time and even within one of the existing religions there is a great diversity of rituals, ceremonies, activities, texts, and so on. As Mikel Burley points out, in his chapter in the volume, the term ‘Hinduism’ is used to ‘cover an assortment of cultural and religious phenomena that are so variegated as to place in question the coherence of the concept’ (38). Both ‘religion’ and ‘Hinduism’ are what Wittgenstein called ‘family resemblance concepts’. That is, religious practices (and Hindu practices in particular) are diverse in such a way that they have no one thing in common that makes them religious but nonetheless they are tied together through resemblances in the way in which family members resemble one another without sharing a single feature in common among all of them.

In discussing the various conceptions of religion Andrejč is eager to emphasize another way in which they do not count as theories. That is that they are not intended as constituting an explanation which excludes explanations in other terms. These conceptions can be combined, and indeed may well need to be combined in order to gain a reasonable understanding of religion. It is implausible, for example, to claim that all religious utterances and texts are composed of grammatical propositions (and we should also note that grammatical propositions are diverse). Recognizing the possibility that certain things said or written within a religion might be quite unlike empirical propositions, which are supported by evidence, is an important insight. It undermines the kind of account of religion that pits it against science, as in the work of people like Richard Dawkins. However, we should not expect that all religious writings and utterances are going to fit into a single mould. O. K. Bouwsma reports that when he told Wittgenstein that a lecturer was to speak on the nature of religious truth, Wittgenstein responded by saying that ‘there is no sense in talking about religious truth in general. What religious? What truth? . . . religion takes many forms, there are similarities, but there is nothing common among all religions’ (O. K. Bouwsma, Wittgenstein: Conversations 1949–1951, ed. J. L. Craft and R. E. Hustwit (Indianapolis: Hackett, 1986), 54–55).

We should also notice that there are significant disagreements among those who emphasize one or another of these conceptions. When Wittgenstein argued that religious (and ethical and aesthetic) propositions were nonsensical he did not intend it in a dismissive way. In a letter to Ludwig von Ficker Wittgenstein said of his Tractatus ‘that my work consists of two parts: of the one presented here, plus all that I have not written. And it is precisely this second part that is the important one’ (G. H. von Wright, ‘Historical Introduction: The Origin of Wittgenstein's Tractatus’, in Prototractatus, ed. B. F. McGuinness, T. Nyberg, and G. H. von Wright, tr. D. F. Pears and B. F. McGuinness (London: Routledge, 1971), 15–16) and he ended his ‘Lecture on Ethics’ in 1929 by saying that the tendency to ‘run against the boundaries of language’, as those who write about religion do, was ‘a tendency in the human mind which I personally cannot help respecting deeply’ (‘Lecture on Ethics’, 44). However, there are people who have taken inspiration from Wittgenstein who have argued that in order to be consistent in his rejection of metaphysics Wittgenstein should have also rejected religion as nonsense. For example, Kai Nielsen has argued that Christianity is inescapably metaphysical, and that Wittgenstein has dismissed metaphysical systems as ‘houses of cards’, and so ‘that very form of life, metaphysically infused as it is, should be said by Wittgenstein and Wittgensteinians to be incoherent’ (Kai Nielsen, ‘Wittgenstein and Wittgensteinians on Religion’, in Mark Addis and R. L. Arrington (eds) Wittgenstein and Philosophy of Religion (London: Routledge, 2001), 147).

Interpreting Interreligious Relations with Wittgenstein is not only diverse in terms of the variety of uses made of Wittgenstein's work. It is also diverse in terms of the religions and religious movements discussed. Daniel Weiss, in his chapter, looks at the philosophical understanding of Judaism found in the work of Maimonides and compares it to the understanding of Judaism found in classical rabbinic literature. He suggests that the philosophical problems found in traditional texts by Maimonides are only problems if you come to those texts with certain philosophical presuppositions. Wittgenstein's work is brought in to show that Maimonides’ attempt to impose consistency on scriptural texts results in confusions. Thomas Carroll, in his chapter, looks at the various religions recognized in China – Buddhism, Catholicism, Daoism, Islam, and Protestantism – as a way of examining complexities in the meaning of ‘religion’. The concept of ‘religion’ was brought to China in a situation of ‘colonial or sometimes quasi-colonial circumstances with the West’ (64) and it is a concept with connotations of Protestant Christianity. The situation in China is interesting both as a way of illustrating how the meaning of ‘religion’ has been shaped by history and as a way of illustrating the importance that attaches to ascriptions of religious belief, and their political and legal ramifications.

Why is it a virtue of this volume that it contains such a diversity in terms of the religions discussed and of conceptualizations of religion? For one thing, if we want to deepen our understanding of what religion is we need to gain an appreciation of the incredible diversity of religions and religious practices. In terms of coming to comprehend Wittgenstein's relevance to understanding religion and interreligious relations it helps to have a sense of the range of different tools and examples he used. We might come to understand religious practices by comparing them to more familiar practices, by using analogies like kissing the picture of a loved one, and we might come to recognize similarities between central religious commitments and ‘hinge’ certainties. We need to attend carefully to the particularities of the texts, rituals, sermons, prayers, dances, meditations, mantras, punishments, and so on, that are deemed ‘religious’ and ‘look and see whether there is anything common to all’ and when we do look we find that there are ‘similarities, affinities, and a whole series of them at that’ (Wittgenstein, Philosophical Investigations, §66).

Robert Vinten is grateful to the FCT for the support they have provided (grant ref: PTDC/FER-FIL/32203/2017) while he was working on this review.