Jordan Howard Sobel Logic and Theism. Arguments For and Against Beliefs in God. Cambridge: Cambridge University Press 2004. Pp. xix + 652.

 Within natural theology and philosophy of religion arguments for and against the existence of God have been given, claiming that someone following only the lead of reason would see thus that there is a God or that there cannot be. There are quite some of these arguments and the literature is corresponding to the importance of the matter in point vast. Jordan Sobel has written a monumental study of some 650 pages (the last hundred being notes) outlining the most (in)famous of these arguments. The book provides a detailed reconstruction of each argument and discusses in a balanced way proposal for improving the argument in question. Not only giving its length, but more so the succinct and precise way Sobel puts the matter this is by far the most comprehensive and detailed discussion of arguments on God that is around (in a single volume). As the title suggests Sobel uses the tools of logic to reconstruct the arguments. The main text of a chapter contains the discussion, the formalization of the argument in question and in most cases informal reasoning for or against belief in God, appendices in the chapters set out the tools used and present the proper proofs for the claims made or proper formal renderings of the informal proofs given. The logic used consists mainly of First Order Logic in a somewhat unusual natural deduction format, that one can, however, easily adapt to. Some arguments need some basic modal logic, others use basic set or probability theory and Baysianism. Anyone who has mastered a course in First Order Logic and has heard of the other fields should have no difficulties with this. (There are, as usual in books with lots of formula, a few typos, but the reader following the text can always guess what should be written there.) I recommend this book to anyone being interested either in the philosophy of religion as such or in the painstaking reconstruction of non-trivial philosophical arguments.

            The book is divided in five parts. The first chapter being a part of its own concerns the concept of divinity. The second part concerns arguments for the existence of God and consists of a chapter on the classical ontological arguments, one on modern modal ontological arguments, one on Gödel’s ontological proof, one on Aquinas’s proof by first causes, one on cosmological arguments, one on arguments from design, and a chapter on miracles. The third part deals with the common conception of God, and consists of one chapter dealing with the concept of omnipotence and one dealing with omniscience. The fourth part contains the arguments against the existence of God, one chapter dealing with evidential arguments from evil, one dealing with the logical problem of evil. The fifth part dealing with practical arguments for and against God consists of a single chapter presenting several versions and refinements of Pascal’s wager. What is missing is a chapter or an introduction reflecting on what the book is doing. This is unfortunate for two reasons. First, religious people supposedly do not believe because God was proven to them, they do not expect Him to be disprovable, the very idea of approaching faith in this philosophical (i.e. fallible) manner is anathema for a stout believer. Thus it is necessary to reflect why there is natural theology and who uses it for what (as Aquinas claims that it supports belief …). Secondly, no argument establishes just a conclusion. An argument establishes a conclusion given its premises and the logic used. So given some conclusion supposedly establishing the existence or non-existence of God a critic can always either turn the argument around seeing it as an argument against one of the premises or can claim that either the logic used is not sound, or at least not sound as applied in this area. The later option is the more live as we have seen a number of non-classical and philosophical logics – and even set theories – coming up in the last century. Thus the discussion of some argument for or against God has to reflect both options. This methodological meta-reflection is missing in the book, but Sobel in fact often tries to cover both ways of reaction (e.g. when discussing the employed set theoretical principles in arguments against the consistency of omniscience).

            Sobel does not give concluding recommendations whether one should or should not believe in God, but he dismisses some of the traditional arguments and sees greater strength in others. Some classical ontological arguments (e.g. Descartes’) are rejected, since the move to define something into existence seems not only too suspect, but actual can be shown to fail logically in misusing existential quantification. Others (e.g. one going back to Anselm) presuppose that what is conceivable is possible. This, however, is a very controversial thesis itself. And on this assumption the modern modal versions (e.g. by  Plantinga) of the ontological argument are – despite their formal sophistication – no improvement. Too permissive tools of cross-world definition of concepts deliver not only God, but dragons and whatever you like to have around! Gödel’s proof, on the other hand, really works (given the logical background), but the concept of ‘God-like being’ that is employed is much too wide to resemble the classical concept of God – Gödel proofs too much. Arguments from first causes rely on a questionable principle of sufficient reason, a strong version of it (in Leibniz) yields breakdown of all modal distinctions (i.e. makes the world itself necessary). A principle of complete reasons goes against the existence of contingent truths. Arguments from design received their death blow from evolutionary explanations, Swinburne’s cumulative design argument contains a fallacy in probabilistic reasoning with cumulative evidence. Hume’s argument against believing in miracles can be given a formally valid rendering. The common conception of God Sobel takes to include a strong conception of omniscience and omnipotence, where ‘strong’ is spelled out either as ‘at all times’ or ‘essentially’. These distinctions generate – not only in these two chapters – several versions of the argument under discussion. Essential omnipotence turns out to be definable, but not applicable, since the famous counter-argument of making a stone one cannot lift goes through. Grim’s more recent arguments against omniscience arguing by Cantor’s Theorem against the existence of a set of truths and thus against the possibility of a set of all ‘things’ an omniscient being knows can be modified in a way that relies less on ontological controversial assumptions about propositions and that uses weaker set-theoretical principles. Still these (valid) arguments make use of diagonalization assumptions that may be at least controversial. Sobel finds fault with Rowe’s evidential argument from evil, but assents to the incompatibility of evil and the existence of a perfect being. The wagers in the manner of Pascal depend heavily on the background assumptions a person the wager is offered to accepts. Once these assumptions (like God rewarding the wilful believer) are made decision theoretic reasoning delivers a verdict on believing or not. Sobel just rejects the objection that one cannot make oneself believe something by will.

Sobel often highlights what a defender of faith had to assume to get rid of the arguments against God. (This concerns the general remark above, how arguments may be turned around or re-interpreted.) In the probabilistic cases like the miracle reports or design arguments the force of the arguments rests on the prior probabilities someone may assign. In this way probabilistic arguments can also be rejected or turned around! If,  for example, the prior probability assigned to God’s existence is much higher than the probability of His non-existence then the existence of evil may not raise the probability of non-existence to over 50% (which may be taken as the crucial mark).

            Sobel seems inclined to see the balance of the arguments to be in favour of rejecting God’s existence, this being taken as the existence of a perfect being as conceived in philosophical theology. Some of the arguments live from the strict understanding of being perfect, omnipotent or omniscient. Whether these arguments have force against a somewhat reduced concept of God – as is supposedly the case in Christianity or Islam – is an open question. Sobel sees this point, but does not address such historical conceptions of God and their reply to the arguments given. That is understandable, since this may have taken some more hundred pages, however the force of what the arguments against omnipotence, omniscience (in the third part) and the arguments from evil (in the fourth part) show thus has to be taken with caution. Defenders of faith like van Inwagen start here. Someone like van Inwagen, who certainly shares Sobel’s rejection of equating conceivability with possibility, would add further scepticism on modal epistemology. Sobel’s stepwise improvement of the logical argument from evil, for example, relies not only on us knowing that what we consider evil is evil, but on stepwise weakened major premises one may increasingly doubt (going from ‘Evil exists’ to ‘If there is a best possible world, the world is improvable’).

            Anyone taking on the task of widening the scope of the arguments towards criticising Christianity or Islam, and anyone taking on the arguments from the mutual support of, say, the claims of a Christian weltanschauung should start with Sobel’s book. Since 650 pages are a lot one may start with the chapters dealing with the ontological arguments. Here you can see the strength, quality and sometimes originality of Sobel’s work best.



Manuel Bremer

Philosophisches Institut

Heinrich-Heine-Universität Düsseldorf

Universitätsstraße 1

40225 Düsseldorf