The titles of these books may give the impression that they attempt the same task. They do not. The dictionary pages are set in two columns and most definitions, whether of terms (e.g. aseity, dharma, doubt, hell, language games, natural law, everlasting …), personal names (e.g. Al-Ghazali, Bergson, Bultman, Epictetus, Kant, Mencius, Wittgenstein …), philosophical systems or positions and religions (e.g. Christianity, Existentialism, Gnosticism, Islam, Jainism, Occasionalism, Neo-Platonism, Process Philosophy, Rationalism, Realism …) occupy a column or less. The entries, by different hands, are identified only in the acknowledgements and by the name of the writer rather than by topic so that it is more difficult than it need have been to discover who wrote what.

As properly becomes a dictionary, the entries do not presume to be controversial but give the generally accepted meaning or basic information. The entries for Martin Buber and for existence give a flavour of what to expect: ‘Martin Buber (1878–1965). Buber stressed the primacy of personal over against impersonal relations, which he formulated in terms of “I-You” or “I-Thou” relations, rather than “I-It”. The relation to God is a high form of the “I-Thou” relations. In 1925 he translated the Hebrew Bible into German, in collaboration with Franz Rosenzweig in Frankfurt.’ There follows a list of some of his publications. That seems to me to be a good brief definiton for someone who knows him only by name – and, whatever about the reviewer, the user of a dictionary usually consults it to discover the meaning of an unfamiliar word. The entry for Existence reads: Some philosophers treat ‘existence’ as a property and distinguish between the properties of existing contingently and existing necessarily. Other philosophers resist thinking of ‘existence’ as a property and claim that it is dispensable in our descriptions and explanations of the world; e.g. rather than affirm ‘lions exist’, we should say ‘there are lions’. In each case, there is evidently more to say but what is said is appropriate to a dictionary.

Most of the entries that I was competent to check seemed to me to be good although, inevitably, there are some oversights. The entry for Robert Boyle omits the fact that his most important and enduring discovery was the relation between pressure and volume in an inert gas, and the list of Avicenna's work ought to have included The Book of Scientific Knowledge.‘These defintions, as the editors write, are only the beginning of philosophical exploration’ (p. x). There is a good introduction, a useful chronology and a very valuable thematic bibliography (pp. 253–85).

Unlike A Dictionary, Key Terms is a set of essays by a single author. In the former the entry for ‘naturalism’ takes up less than half a column but in Key Terms an entire page; ‘agnosticism’ in the first is half a column; in the second a page. Some essays, for instance, the ‘Kalam cosmological’ argument runs through four pages. A Dictionary tells how the term ‘ontological argument’ is used; in Key Terms there is a seven page discussion of the idea. The books, then, serve very different purposes as do dictionaries and encyclopaedias. Several essays in Key Terms are in themselves interesting and illuminating contributions to contemporary debate, some are closer to being simply definitions (the entry on ‘Omnipotence’ is close to being a definition of the term with an addendum about God's foreknowledge and freewill) but the entire collection is an excellent introduction to, and discussion of, contemporary questions in the philosophy of religion.