I find this book written densely. This has its good and its bad points. On the former, Cross has managed to make many claims about many authors and topics in relatively few pages—although his points tend to be repeated in the course of the book. On the latter, I at least find it hard to assess his claims without a great deal of unpacking and amplification that goes beyond what he has said. A lot of my perplexity may be due to Cross’ style of writing, which has many discussions continue on from the text to the notes. He also has the habit, bewildering to me, of skipping from one author to another within a paragraph. The organization of the book by topic and not by author makes it hard to piece together the theories of the individual authors, although Cross helpfully supplies many Cross-references [sic]. I should stress that this is a book that presumes a great deal of background on the part of its reader: Latin; modern and medieval theology; general medieval culture etcetera. It will not play to a general audience. At the risk of being unfair by snatching a sentence out of context, let me give a sample: ‘But mere existence as a real object, with relations to God’s exemplar causality (essence) and efficient causality (esse), is not, according to Richard [of Middleton], sufficient for subsistence.’ [270] This jargon, like treating existence as an object, will put off the philosophers; the emphasis on reason and not on faith will put off many modern theologians.

Still let me stress the merits of the book. At the very least, this book is valuable because Cross has assembled a great deal of relevant material on the Incarnation, both the medieval sources, from Aquinas to Scotus and Olivi, and the modern literature thereon. He also has written with an eye to the current literature and issues in Christology. He makes many insightful comments and claims about the arguments he presents as well as those in the secondary literature. His bibliography is fairly complete, although perhaps having the lacunae typical of the Anglo-American scholars: rather short on Continental sources, e.g., L. Honnefelder and J. Aertsen, although he does cite more than most, and on earlier Patristic and Islamic sources.

Cross has set himself the topic of the metaphysics of the Incarnation. By this he means to investigate what sorts of objects existing in re must be presupposed in order to have a satisfactory, orthodox account of the Incarnation. Must not only the individual things, like Jesus Christ (the suppositum), exist in re, but also the second Person of the Trinity and the human nature of Christ? What do the medieval authors of his period say? Cross claims that this topic of their metaphysics of Christology has been relatively neglected today. [24-6]

Despite setting himself the topic of the metaphysics of the Incarnation, Cross ends up discussing other issues, such as the problem of its consistency. In his defense we might think that this problem could be handled ‘metaphysically’, i.e., semantically, by given a model-theoretical account of consistency. Yet Cross gives the syntactic account. [192ff.] He ends up concluding (not too convincingly to me) that the use of the qualifying phrases, ‘qua God’ and ‘qua man’, does not resolve the contradictions that seem to arise in predicating of Christ ‘creature’ and ‘not a creature’ etc. [204] Rather, either we have to accept that Christ is composed of distinct parts having the contradictory predicates (to use the specificative analysis), or we modify the attributes of Christ so as to eliminate the contradictions (to use the reduplicative analysis). [viii; 205] It is odd that Cross says that the medievals ‘radically underestimate’ this problem of consistency though. For the logical theory of qualifications, reduplicatio, seems to have arisen precisely as a way to understand the orthodox creed that Christ is perfectly God (as I have claimed in On Reduplication (Leiden, 1996). Indeed, the Athanasian Creed states that ‘Christ is perfectly God and perfectly man…(and) is equal to the Father with respect to his divinity, but less than the Father with respect to his humanity.’ [‘Quicumque vult,’ Enchiridion Symbolorum, ed. Denzinger, 40, p. 18]

Cross aims at establishing the following main claims: ‘…medieval understandings of the individuality of the assumed human nature in Christ can be used to buttress a two-minds…Christology that entails divine passibility and mutability.’ [viii; cf. 317] He goes so far as to claim that any coherent theory of the Incarnation must accept these ‘divine limitations’. (So much for Catholic orthodoxy: have we not then given up the traditional infinite divine attributes?) Cross believes ‘…that the medievals tended to see Christ’s human nature as an individual in the genus of substance…[and] that persons are just natures of a certain kind.’ [6] He says that a trope theory of substances or a part-whole analysis of the Incarnation will end up with such a view. [22] In order to avoid a bare-particular view of substance, Cross says, we are going to end up with a position on the Incarnation like Scotus’. [314] Moreover, he thinks that a Scotist negation theory of the ‘subsistence’ of Christ’s human nature will work out the best. [289; 301] This is the theory that both persons and individual natures are primary substances existing in re, and that the former are distinguished from the latter by no positive attribute but only by negative features or by the absence of an attribute. [2; 285] If we follow Cross’s lead in Christology, ‘we will not need to do much metaphysical work not already done by Scotus.’ [314]

In addition to these general claims, Cross also has many particular ones advocating his interpretation of the various medieval theologians. He, like me, finds Aquinas starting from a parts-whole model but then wavering and trying out other strategies in order not to make the human nature accidental to Christ. [51-4] Cross finds Scotus’ position more sophisticated, although sometimes preferring Olivi. [121; 150; 189; 297; 311]

Cross begins by quoting Hobbes. Hobbes has a low opinion of scholasticism in general and of such theology in particular: ‘names that signifie nothing; but are taken up, and learned by rote from the Schooles, as hypostatical, transubstantiate…’ [1] Cross seeks to defend the medieval faithful here. Here, I sigh, he has failed. For the style of the book has many technical medieval terms used en passant without much grounding, either in their historical roots or in philosophical analysis.

In addition to the sample quoted above, let me discuss briefly two issues. These will raise some substantive points, as well as explain some of my perplexities.

First, Cross has a conception of ‘subsistence’ that seems foreign to medieval times. Following C. J. F. Williams, he identifies persons with Aristotle’s primary substances, and natures with secondary substances, which, he thinks, are ‘formal concepts’. Both exist in re. Williams calls the type of existence in re peculiar to primary substances ‘subsistence’. [2] Williams sees the medievals making the mistake of trying to figure out how to attach subsistence to a nature to make a person. Cross seeks to defend medieval Christology as not making a mistake. [239] I like the project. Still, using ‘subsistence’ in this way has problems. Let me sketch why, although I shall not be able to defend these claims here.

First, ‘subsistence’ for medieval Aristotelians was generally a term used to indicate a sort of quasi-existence that is not the existence in re of individual substances. This use goes back to an Aristotelian position that in the category of relation the relata strictly speaking are not the individual substances but certain accidental attributes of individual substances: ‘master-slave’ and not ‘Muhammad-Abdul’. [Cat. 7] Plotinus calls such quasi–subjects ‘hypostases’. [Enneads VI.1.9.28–32; VI.1.7.23–8] ‘Subsistence’, the noun form, came to signify the sort of real existence such relations had. The same notion came to be applied also to universals or quiddities that had some sort of objective ‘existence’ independent from the things in which they were but still did not exist in re as independent objects. Thus Avicenna will say that these quiddities in themselves ‘subsist’ (have ‘qiwm’ or ‘kaun’) but do not ‘exist’. [Al-Maqūlāt, ed. M. Al-Khudayri et al., Cairo, 1959, 61,6–9; Alexander, in Met. 483,26–8]

This use of ‘hypostasis’ and ‘subsistence’ became yet more substantial in dealing with the Trinity so as to have three Persons distinguished by relations like paternity and having some independence while there remains only one God. Calling a divine Person an ‘hypostasis’ makes it have ‘subsistence’ but not ‘existence’ (huparxis; wujud; esse) as a separately existing individual, so as to avoid polytheism. [Cf. Basil, Patrologia Graeca Vol. 30.2, De Hominis Structura Oratio 1, 14C] As Cross notes, with Boethius’ De Persona, ‘hypostasis’ became even more substantial through Boethius’ defining ‘persona’ as a substance. [178; 239] Aquinas for instance at times will speak of an hypostasis as a substance. [SCG IV.38] Still the relational basis with its ‘quasi’ natures remains.

Assuming such an account, and looking again at Cross’ use of ‘subsistence’, I find it hard to align many medieval theories with his use of ‘subsistence’. Thinking of subsistence as he does crunches together various conceptions of ‘existence’ and ‘things’ (res) that medievals were at pains to keep apart. Again, Cross tends to think of this ‘subsistence’, a.k.a. ‘esse’, as a thing or a part to be added on to a nature (the quiddity in itself). [246; 256’ 268–9] If the esse is a part, it is surely not one in the same sense that the quiddities are parts: ‘existing’ does not show up in a definition or description; the esse is a way in which natures are or exist, namely, in re or in intellectu. Likewise matter is not a constituent in the way that natures are: the distinction of potency and act comes to bear here. Talking of natures ‘qua subsistence’ or ‘a nature that is the subject of its own esse’ [244; 255] tends to confuse—although the language of those like Giles of Rome tends to suggest it. [267] I do not say that all this is insurmountable but makes it hard to follow the discussion. Once again we have an unpacking problem.

Second, a great part of the book concerns the issue whether Christ’s assumed human nature is universal or individual. [Cf. Index, ‘Christ, human nature of’] Most of the authors whom Cross discusses have of course a general theory of natures in their metaphysics. Indeed they regularly cite the same texts, especially of Aristotle, his Commentator Averroes, and Avicenna. Now the Incarnation is a difficult case for any theory. So a likely way to proceed is to start with ‘what is most evident to us’ (to coin a phrase) and then proceed to such difficult cases. In this way too, the theory presented for the Incarnation will be systematic and grounded on universal principles and not be ad hoc. (Indeed, Ockham, in having to admit the formal distinction and Scotism into his account of the Incarnation etc. made the theory ad hoc, and divorced it from natural science and philosophy. Here were the seeds of the end of medieval theology. But this is a large claim, and I but mention it here.)

My point then is this. We should begin by developing a metaphysics adequate to explain our ordinary, everyday experience and then use the results to proceed on to the mysterious case of the Incarnation. Many of the authors discussed by Cross – Aquinas, Henry of Ghent, Scotus – did so. In their general metaphysics, they tended to accept in general the doctrine of the threefold distinction of quiddity (triplex status naturae), developed mostly by Avicenna. Now they all cite regularly the same passage from Metaphysica V.1 that holds that a quiddity in itself is neither one nor many, neither individual nor universal. Cross keeps insisting on the dilemma: individual or universal. [e.g. 94–7] But for the medievals there seems to have been a third option, and hence the dilemma looks to be a false one. At the least, Cross owes us more explanation here.

Of course, giving such explanations and doing such unpacking would increase Cross’ task considerably. Yet to do the medieval theories justice surely that needs to be done. Perhaps the very magnitude of this task explains why there have been few books focussing solely on the metaphysics of the Incarnation, as Cross complains.