The favorite objection used to be that if a man was eaten by cannibals, there would be certain particles of matter which would belong both to the cannibal and to the victim of the experiment. And it has often been pointed out that, even in civilized countries, we may find ourselves eating mutton that comes from a sheep which has been browsing in the churchyard, and so the same difficulty arises in a rather more circuitous way. And, while arguments like these have suggested to irreverent minds the possibility that there will not be enough bodies to go round, so to speak, on the day of judgement, it is equally easy to suggest that there will be too many bodies going about; because after all you and I change, even in the course of a single year, nearly all the material particles which go to make up our bodies, so that it would be very hard to know which of a series of material bodies we are going to rise with. Sceptical difficulties like these have led some Catholic thinkers to suggest - and I understand that it is an allowable position - that the identity between the earthly and the heavenly body is formal, rather than material; depends upon the persistence, not of actual material particles, but of the form which organized them. The trouble about that is that if you are a good Thomist - if you are a Scotist, I fancy you get out of it, somehow - you hold that the from which organizes our material bodies is nothing other than the soul . . . and it is difficult to see how or why the re-embodies soul in heaven differs from the disembodied soul in purgatory.
For this reason, the more cautious among Catholic authors are content to point out that we needn't insist on the necessity of reassembling every individual particle of the terrestrial body in heaven. Part will do: and, precisely in view of the large number of transformations which our body has been through, it ought to be possible to make good any losses through cannibalism. I confess that I find it a little difficult to frame my mind with confidence into this particular type of orthodoxy. I should prefer to think that, without meddling with any controversies between Thomists and Scotists, we can take refuge here in our ignorance. [...]
- Ronald Knox, "The Resurrection of the Body", in The Hidden Stream