Orthodox truthmaker theory cannot be defended by cost/benefit analysis

Transcription

1 orthodox truthmaker theory and cost/benefit analysis 45 Orthodox truthmaker theory cannot be defended by cost/benefit analysis PHILIP GOFF Orthodox truthmaker theory (OTT) is the view that: (1) every truth has at least one truthmaker (truthmaker maximalism), (2) the existence of a truthmaker necessitates the truth of the proposition(s) it is a truthmaker of (truth maker necessitarianism). (Cameron 2008) In the person of Ross Cameron, OTT has bitten off more than it can chew. Previously, the view was defended by appeals to brute intuition: My hope is that philosophers of realist inclinations will be immediately attracted to the idea that a truth, any truth, should depend for its truth [on] something outside it, in virtue of which it is true (Armstrong 1997: 123). Cameron (2008), a defender of OTT, has recently offered more accountability for his party, by suggesting that OTT ought to be subject to the cost/benefits test of philosophical worth. If we are to believe OTT, then it must, like any other metaphysical doctrine, show itself to be theoretically worthy. OTT has an immediate disadvantage in such contests: as soon as you commit to it, you have to believe in loads of stuff. OTT comes with baggage. If you are not an orthodox truthmaker theorist, you can think that there are no hobbits because...well, there are no hobbits. There used to be dinosaurs because...well, there used to be dinosaurs. Gordon Brown is dour because...ahem, he is dour. As soon as you commit to OTT, you have got to do more work, which means investing in more things. It seems that the mere existence of all the entities that presently exist does not necessitate that there are no hobbits (because there is a possible world where there is everything that actually exists and there are hobbits as well), or that there were dinosaurs (there is a possible world which contains everything that actually presently exists, but in which there were never dinosaurs), or that Gordon Brown is dour (there is a distant possible world in which Gordon Brown has a cheery disposition). So we need more stuff. Cameron does not deny that there is this immediate theoretical cost to investing in OTT. What then is the theoretical advantage to be had that might make up for this cost? According to Cameron, OTT can offer us an elegant theory of truth: for each and every true proposition, that proposition is true because there is some entity which necessitates its being true. Truthmaker theory says the brute truths are all of a kind: they are the truths that concern only what there is....the truthmaker thought is that explanation only bottoms out at existence facts: for God to give a Analysis Vol 70 Number 1 January 2010 pp doi: /analys/anp132 ß The Author Published by Oxford University Press on behalf of The Analysis Trust. All rights reserved. For Permissions, please journals.permissions@oxfordjournals.org

2 46 philip goff complete plan of the world He needs only make an inventory of what is to exist. (Cameron 2008: 125, ) Truthmaker theorists who deny OTT will have a more complex story to tell about truth. Truthmaker theorists who deny maximalism will have to say that some truths are true because they have a truthmaker (<Gordon Brown exists> is true because it has a truthmaker, i.e. Gordon Brown) and some truths are true for some other reason (<hobbits don t exist> is true because certain entities do not exist, <dinosaurs used to exist> is true because certain entities used to exist). Truthmaker theorists who deny necessitarianism will say that, at least in some cases, true propositions are true because of what things there are and how those things are (<Gordon Brown in dour> is true because (i) Gordon Brown exists, (ii) Gordon Brown is dour). 1 Jonathan Tallant (2009) has argued, rightly in my view, that a little less simplicity in our theory of truth is a price worth paying for more simplicity in reality. The shrewd metaphysician, in general, will be willing to trade theoretical elegance for ontological elegance. But I want to go further. I suggest that the OTT s simplification of the notion of truth is an oversimplification; and consequently is not in fact a theoretical advantage but a theoretical cost. Cameron, like many truthmaker theorists, embraces the metaphor of God instructing His angels to create the world. For the orthodox truthmaker theorist, God only tells His angels what to put in the world (remember, the explanation of truth bottoms out at existence facts ). Cameron views this as an advantage of his view. To my mind, this is a strange and arbitrary limiting of the creative powers of God. Why is God only able to tell His angels what to put in the world? Why can t He also tell Gabriel what not to put in the world ( Gabriel, whatever you do, don t make any hobbits! )? Why can t He tell him to create some things and then destroy them ( Right, Gabriel, I want you to make some dinosaurs and then I want you to annihilate them )? Why can t He give Gabriel instructions on how He intends the things He wants put in the world to be, rather than merely giving instructions on what things He wants put in ( I tell you Gabe, I m in a bad mood, I want you to make Gordon as dour as you possibly can... ). The writers of recipes are able to demonstrate this kind of flexibility, so why is God not? Alternately, if God is able to do these things, why doesn t He? Why does He go in such a roundabout way to make true His favoured set of propositions ( Ok, Gabriel, listen carefully, because I will say this only once... I need it to be true that there are no hobbits, so I want you to create all 1 Of course, there may be realists who deny that there is such a thing as truthmaking. Cameron offers reasons to prefer the truthmaking conception of realism over such antitruthmaking conceptions of realism (Cameron 2008: ). Those who are not already inclined to realism are unlikely to be persuadable to the virtues of OTT.

3 orthodox truthmaker theory and cost/benefit analysis 47 the things there are, and then create the fact that those things are all the things that there are... 2 )? God s eccentric behaviour here seems inexplicable. Why doesn t He just tell Gabriel not to make any hobbits? Cameron s God certainly has His work cut out for him; I would be surprised if He has time spare to take Sunday off. These theological metaphors are used in philosophy as a vivid way of representing metaphysical possibility. When we talk of what God could have done, we are really talking about how things might have been. Cameron s limiting of God s creative powers to merely the capacity to bring things into existence corresponds to an impoverished conception of metaphysical possibility. In the absence of a commitment to OTT, it seems that there is a world where: (i) there are no hobbits, (ii) there is no entity (or entities) whose existence necessitates that there are no hobbits. What reason could there be to think that God could not create such a world? For the orthodox truthmaker theorist, there cannot be such a world, for it would be a world at which a proposition, i.e. <there are no hobbits>, is true while lacking a truthmaker. 3 Consider the world with a history just like ours, but in which (i) presentism is true, (ii) there is nothing presently in existence which necessitates that there were dinosaurs. Consider the world in which Gordon Brown is dour, but there is nothing in existence which necessitates that Gordon Brown is dour. Don t such worlds seem possible, at least until we have a substantive philosophical argument to the contrary? Doesn t it seem that God could have created such worlds? The orthodox truthmaker theorist has to deny this. I think God would be perplexed, perhaps even a bit annoyed, by the orthodox truthmaker theorist s lack of faith in His abilities. Merricks (2007) has suggested the following argument against OTT. (1) If OTT is true, then presentism is false. (2) Presentism is not false. (3) OTT is not true. This argument is valid, but its premisses are contentious. Premiss 1 is arguably false, as there are forms of presentism which commit to their presently existing things which necessitate the truth of truths about the past, and so are consistent with OTT. We can quickly rectify this in the following way. 2 This is what God instructed Gabriel to do if Armstong s recent theory of the truthmakers for negative truths is correct (Armstrong 2004). 3 Unless OTT is merely contingently true. Could there be a theory of what it is for a proposition to be true which was itself merely contingently true? If God could break OTT, why didn t He when he made the actual world? Until such a view is explicitly spelt out/defended, I will continue to suppose that OTT is either necessarily true or necessarily false.

4 48 philip goff 1* If OTT is true, then it is not the case that both: (i) presentism is true, and (ii) the entities which presently exist do not necessitate that <there were dinosaurs> is true. 2* Presentism is true, and the entities which presently exist do not necessitate that <there were dinosaurs> is true. 3* OTT is not true. The problem now is that Premiss 2* is a highly contentious theory of reality. However, we do not need such controversial premisses to get to the conclusion. As I have shown above, the mere possibility of a world with the same history as ours, such that (i) presentism is true, (ii) the existence of the entities which presently exist does not necessitate that <there were dinosaurs>, is inconsistent with OTT. Consider, then, the following argument. 1** If OTT is true, then God could not have made a presentist world, with an identical history to our own, such there is nothing that presently exists which necessitates that <there were dinosaurs> is true. 2** God could have created a presentist world with an identical history to our own, such that there is nothing that presently exists which necessitates that <there were dinosaurs> is true. 3** OTT is false. We can create similar arguments involving God s ability to create worlds where there are no hobbits and no entities which necessitate that there are no hobbits, or God s ability to create worlds where Gordon Brown is dour but there are no entities that necessitate that Gordon Brown is dour (I think such arguments would be even more plausible than the argument above which relies on the metaphysical possibility of presentism). A commitment to OTT s theory of truth constitutes an arbitrary restriction on metaphysical possibility, and this seems to me a cost of the theory rather than a benefit. Of course, which metaphysical theories one endorses can have implications for what one takes to be metaphysically possible. Those who believe that I am essentially a human being will believe that God could not have made the world such that I was a boiled egg. But OTT is not a set of metaphysical commitments, but a principle intended as a starting point for metaphysical enquiry. The proponent of OTT is obliged to tell us why it is beneficial to begin with a principle which rules that so many scenarios which seem prima facie possible are not possible. This arbitrary restriction on metaphysical possibility is the result of OTT s commitment to explanation of truth bottoming out at existence facts. If all truths are ultimately to be explained only in terms of what exists, then God is limited in what he can tell his angels to do: he can only tell them what items

5 orthodox truthmaker theory and cost/benefit analysis 49 to put in the world. The theory of truth which OTT offers is, to this extent, theoretically costly. But perhaps accepting this disadvantage is consistent with holding that this theory of truth is nevertheless elegant, and for this reason theoretically virtuous. In response to this, we can note that there are often cases in which maximal simplicity isn t an advisable starting point for enquiry. Consider the dawn of biology; it would have been inadvisable to begin our investigation of the natural world with the working hypothesis that all biological phenomena are fundamentally of the same species. I think that something similar is going on with OTT s theory of truth. A little reflection on our linguistic practices suggests that we are capable of making quite different kinds of truth claim. We can assert that certain things exist. We can deny that certain things exist. We can assert that certain things used to exist. We can deny that certain things used to exist. We can assert that the things that exist are a certain way. We can deny that the things that exist are a certain way. These seem to be quite different kinds of truth claim, and there is no obvious reason to think that any one of these categories of truth claim is dominant, such that we ought to understand all the other categories of truth claim in terms of it. Now perhaps some of these truth claims can be explained in terms of others, for example, perhaps tensed truth claims can be explained in terms of tenseless truth claims. But why think it is an advantage to suppose, at the start of metaphysical enquiry, that all categories of truth claim can be explained in terms of one single category, namely the category of positive, tenseless, existential assertion? Surely it is better to start with the categories of truth claim there seem to be, both positive and negative truth claims, both existential assertions and predications, both tensed and tenseless assertions. As enquiry goes on, we may decide that some of these categories are to be explained in terms of others. We may even find that there is some serious philosophical advantage in explaining all categories of truth claim in terms of one category. But to make such a radical assumption about this from the start seems weird. It is rather like starting biological enquiry with the a priori assumption that all animals are mammals. The supposed elegant theory of truth which OTT offers us is actually a very radical and unmotivated starting point for enquiry. This strange starting point comes with a radical restriction of the space of metaphysical possibility, which also seems unmotivated. The supposed advantages of OTT turn out, on reflection, to be costs. Coupled with the significant ontological costs which inevitably come with the theory, it is clear that OTT can never be justified on a costs/benefits analysis. This is not to say that this is the end of OTT. The theory has so far done very well when supported, not by cost/benefit analysis, but simply by brute intuition. Many seem to share the brute intuition. But if Cameron s attempt

6 50 jan heylen to sell OTT at the metaphysical market place catches on, OTT s days are numbered. 4 University of Birmingham Birmingham B15 2TT, UK philgoff1@gmail.com References Armstrong, D.M A World of States of Affairs. Cambridge: Cambridge University Press. Armstrong, D.M Truth and Truthmakers. Cambridge: Cambridge University Press. Cameron, R Truthmakers, realism and ontology. In Being: Contemporary Developments in Metaphysics, ed. R. LePoidevin, Royal Institution of Philosophy Supplement, 83: Merricks, T Truth and Ontology. Oxford: Clarendon Press. Tallant, J Ontological cheats might just prosper. Analysis 69: Thanks to Nikk Effingham for discussion and to Kirk Surgener and Emma Bullock for slightly sarcastic but helpful assistance. Descriptions and unknowability JAN HEYLEN In a recent paper Horsten (2009) embarked on a journey along the limits of the domain of the unknowable. Rather than knowability simpliciter, he considered a priori knowability, and by the latter he meant absolute provability, i.e. provability that is not relativized to a formal system. (Henceforth, when I speak about provability I mean absolute provability.) He presented an argument for the conclusion that it is not absolutely provable that there is a natural number of which it is true but absolutely unprovable that it has a certain property. Informally glossed, Horsten s argument runs as follows: Suppose, for a reductio, that there exists a property of natural numbers such that it is provable that for some natural number n, (n) is true but unprovable. Then, by the least number principle, there must be a smallest such natural number n. Then there provably exists exactly one smallest number n such that (n) is true but unprovable. Then it is provable that the smallest n such that (n) is true but unprovable is Analysis Vol 70 Number 1 January 2010 pp doi: /analys/anp133 ß The Author Published by Oxford University Press on behalf of The Analysis Trust. All rights reserved. For Permissions, please journals.permissions@oxfordjournals.org