Gonzalo Rodriguez-Pereyra

In this paper I discuss a passage from *Naming and Necessity* where Kripke assumes that the essential properties by means of which a definite description designates are a sufficient condition of its rigidity. I put forward two examples that show the falsity of this assumption. Then I examine the non-rigid character of definite descriptions that designate by means of properties that are sufficient conditions of identity of the objects designated by those descriptions. I conclude that the properties by means of which rigid descriptions designate must be both necessary and sufficient conditions of the identity of the designated objects.

In the 1750s Optimism, the Leibnizian doctrine that the actual world is the best possible world, popularised by Pope in 1733 in his Essay on Man, was a hot topic. In 1759 Kant wrote and published a brief essay defending Optimism, Attempt at some Reflections on Optimism. Kant’s aim in this essay is to establish that there is one and only one best possible world. In particular, he argues against the claim that, for every possible world, there is a possible world better than it and against the claim that there are two or more equally good possible worlds that are better than all the rest. Although it is not clear why, Kant was later dissatisfied with his essay. In this article I shall reconstruct, discuss, and evaluate Kant’s arguments. My evaluation will be negative, and so I think Kant had reasons to be dissatisfied with his essay.

In this paper I argue that Modal Realism, the thesis that there exist non-actual possible individuals and worlds, can be made compatible with Metaphysical Nihilism, the thesis that it is possible that nothing concrete exists. Modal Realism as developed by Lewis rules out the possibility of a world where nothing concrete exists and so conflicts with Metaphysical Nihilism. In the paper I argue that Modal Realism can be modified so as to be compatible with Metaphysical Nihilism. Such a modification makes Modal Realism neither incur further theoretical costs nor lose its theoretical benefits. Thus such a modification constitutes an improvement of Modal Realism.

In this paper I undermine the Entailment Principle according to which if an entity is a truthmaker for a certain proposition and this proposition entails another, then the entity in question is a truthmaker for the latter proposition. I argue that the two most promising versions of the principle entail the popular but false Conjunction Thesis, namely that a truthmaker for a conjunction is a truthmaker for its conjuncts. One promising version of the principle understands entailment as strict implication but restricts the field of application of the principle to purely contingent truths (i.e. those that contain no necessary proposition at any level of analysis). But a conjunction of purely contingent truths strictly implies its conjuncts. So this version of the principle is committed to the Conjunction Thesis. The same is true of the version of the principle where entailment is understood in the sense of systems T, R, and E of relevant logic, since in these systems conjunctions entail their conjuncts. I argue that the Conjunction Thesis is false because a truthmaker is that in virtue of what a certain proposition is true and it is false that, for example, what the proposition that Peter is a man is true in virtue of is the conjunctive fact that Peter is man and Saturn is a planet (or the facts that Peter is a man and that Saturn is a planet taken together). I also argue against other versions of the principle.

I believe in metaphysical nihilism, the thesis that there could have been no concrete objects, because I believe in a version of the subtraction argument, the subtraction argument*, that proves it. But both Jonathan Lowe (2002) and Alexander Paseau (2002) express doubts about the subtraction argument*. Paseau thinks the argument is invalid, and Lowe argues that invoking concrete* objects is unnecessary. Furthermore Lowe attempts to rebut my objections (Rodriguez-Pereyra 2000) to his anti-nihilist argument (Lowe 1998). In this paper I defend the subtraction argument* from Paseau's and Lowe's criticisms as well as show that the premises of Lowe's anti-nihilist argument are still lacking support.

Nominalism, which has its origins in the Middle Ages and continues into the Twenty-First Century, is the doctrine that there are no universals. This book is unique in bringing together essays on the history of nominalism and essays that present a systematic discussion of nominalism. It introduces the reader to the distinction between particulars and universals, to the difficulties posed by this distinction, and to the main motivations for the rejection of universals. It also describes the main varieties of nominalism about properties and provides tools to understand how they developed in the history of Western Philosophy. All essays are new and are written by experts on the topic, and they advance the discussion about nominalism to a new level.

Universals have traditionally thought to obey the identity of indiscernibles, that is, it has traditionally been thought that there can be no perfectly similar universals. But at least in the conception of universals as immanent, there is nothing that rules out there being indiscernible universals. In this paper, I shall argue that there is useful work indiscernible universals can do, and so there might be reason to postulate indiscernible universals. In particular, I shall argue that postulating indiscernible universals can allow a theory of universals to identify particulars with bundles of universals, and that postulating indiscernible universals can allow a theory of universals to develop an account of the resemblance of quantitative universals that avoids the objections that Armstrong’s account faces. Finally, I shall respond to some objections and I shall undermine the criterion of distinction between particulars and universals that says that the distinction between particulars and universals lies in that while there can be indiscernible particulars, there cannot be indiscernible universals.

Gonzalo Rodriguez-Pereyra presents an original study of the place and role of the Identity of Indiscernibles in Leibniz's philosophy. The Principle of the Identity of Indiscernibles rules out numerically distinct but perfectly similar things; Leibniz derived it from more basic principles and used it to establish important philosophical theses. Rodriguez-Pereyra aims to establish what Leibniz meant by the Principle of Identity of Indiscernibles, what his arguments for and from it were, and to assess those arguments and Leibniz's claims about the Principle of Identity of Indiscernibles. He argues that Leibniz had a very strong version of the principle, according to which no possibilia are intrinsically perfectly similar, where this excludes things that differ in magnitude alone. The book discusses Leibniz's arguments for the Identity of Indiscernibles in the Meditation on the Principle of the Individual, the Discourse on Metaphysics, Notationes Generales, Primary Truths, the letter to Casati of 1689, the correspondence with Clarke, as well as the use of the Identity of Indiscernibles in Leibniz's arguments against the Cartesian conception of the material world, atoms, absolute space and time, the Lockean conception of the mind as a tabula rasa, and freedom of indifference. Rodriguez-Pereyra argues that the Identity of Indiscernibles was a central but inessential principle of Leibniz's philosophy.

What I call the argument from almost indiscernibles is an argument, put forward by Robert Adams in 1979, for the possibility of indiscernibles based on the possibility of almost indiscernibles. The argument is that if almost indiscernibles are possible, indiscernibles are possible, but since almost indiscernible are possible, indiscernibles are possible. The argument seems to be an improvement over the mere appeal to intuitions, like that suggested by Max Black, that situations in which there are indiscernibles are possible, for the argument purports to give us a reason that indiscernibles are possible. In this paper I shall assess the argument by examining whether there is support for the conditional premise that if almost indiscernibles are possible, indiscernibles are possible. I shall argue that there are reasons to think that either the premise lacks support or almost indiscernibles are dispensable. If the premise lacks support, the argument does not establish the possibility of almost indiscernibles; if almost indiscernibles are dispensable, the argument is not needed to establish the possibility of indiscernibles.

Are the categorical laws of ontology metaphysically contingent? I do not intend to give a full answer to this question in this paper. But I shall give a partial answer to it. In particular, Gideon Rosen, in his article “The Limits of Contingency”, has distinguished a certain conception of metaphysical necessity, which he calls the Non-Standard conception, which, together with the assumption that all natures or essences are Kantian, is supposed to entail that many laws of ontology are metaphysically contingent. Now, the argument Rosen gives supports the conclusion that all categorical laws of ontology are contingent. I shall argue that the Non-Standard conception and the thesis that all natures are Kantian are incompatible with each other and that, if the Non-Standard conception is true, there must be at least one metaphysically necessary categorical law of ontology, and I shall identify such a law. Thus my contribution to the question of the title of the paper will be that not all categorical ontological laws can be contingent if the Non-Standard conception is true.

Descartes maintained substance dualism, the thesis that no substance has both mental and material properties. His main argument for this thesis, the so-called separability argument from the Sixth Meditation (AT VII: 78) has long puzzled readers. In this paper I argue that Descartes' independence conception of substance (which Descartes presents in article 51 of the Principles) is crucial for the success of the separability argument and that Descartes used this conception of substance to defend his argument for substance dualism from an important objection.

This is a reply to Byeong-Uk Yi who argued that my _Resemblance Nominalism_ fails to account for sentences featuring abstract nouns like Carmine resembles vermillion more than it resembles French Blue and Scarlet is a colour. I accept his criticism of what I said in my book on Resemblance Nominalism about, but then I go on to show how can be accounted for. I reject his criticism of what I said in my book about. I also show how Resemblance Nominalism can account for other sentences featuring abstract nouns

Jamin Asay’s A Theory of Truthmaking is one of the most important books on truthmaking, full of important ideas from beginning to end. One of the most interesting parts of the book is Asay's attack on the explanation-first truthmaking. Explanation-first truthmaking is the explanatory project of explaining why truths are true. This is in contrast with ontology-first truthmaking, the project defended by Asay, and which is the project of answering the fundamental ontological question “What is there?”. Asay thinks explanation-first truthmaking should be abandoned because it is problematic and it offers no benefits over those of ontology-first truthmaking. In this brief paper, I argue that he has not established the problematicity of explanation-first truthmaking, and that explanation-first truthmaking offers benefits over ontology-first truthmaking.

Universals have traditionally thought to obey the identity of indiscernibles, that is, it has traditionally been thought that there can be no perfectly similar universals. But at least in the conception of universals as immanent, there is nothing that rules out there being indiscernible universals. In this paper, I shall argue that there is useful work indiscernible universals can do, and so there might be reason to postulate indiscernible universals. In particular, I shall argue that postulating indiscernible universals can allow a theory of universals to identify particulars with bundles of universals, and that postulating indiscernible universals can allow a theory of universals to develop an account of the resemblance of quantitative universals that avoids the objections that Armstrong’s account faces. Finally, I shall respond to some objections and I shall undermine the criterion of distinction between particulars and universals that says that the distinction between particulars and universals lies in that while there can be indiscernible particulars, there cannot be indiscernible universals.