Ioannis G. Ntagkas

Many philosophers and non-philosophers who reflect on the causal antecedents of human action get the impression that no agent can have morally relevant freedom. Call this the ‘non-existence impression.’ The paper aims to understand the (often implicit) reasoning underlying this impression. On the most popular reconstructions, the reasoning relies on the assumption that either an action is the outcome of a chance process, or it is determined by factors that are beyond the agent’s control or which she did not bring about. I argue that arguments based on this premise fail to apply to some possible agents for whom the non-existence impression arises. On the alternative reconstruction I offer, the impression rests on the assumption that free will requires being involved in the ultimate explanation of one’s actions in a novel sense in which nothing can be involved in the ultimate explanation of anything.

The aim of Modality and Explanatory Reasoning (MER) is to shed light on metaphysical necessity and the broader class of modal properties to which it belongs. This topic is approached with two goals: to develop a new and reductive analysis of modality, and to understand the purpose and origin of modal thought. I argue that a proper understanding of modality requires us to reconceptualize its relationship to causation and other forms of explanation such as grounding, a relation that connects metaphysically fundamental facts to non-fundamental ones. While many philosophers have tried to give modal analyses of causation and explanation, often in counterfactual terms, I argue that we obtain a more plausible, explanatorily powerful and unified theory if we regard explanation as more fundamental than modality. The function of modal thought is to facilitate a common type of thought experiment – counterfactual reasoning – that allows us to investigate explanatory connections and which is closely related to the controlled experiments of empirical science. Necessity is defined in terms of explanation, and modal facts often reflect underlying facts about explanatory relationships. The study of modal facts is important for philosophy not because these facts are of much metaphysical interest in their own right, but largely because they provide evidence about explanatory connections.

The sample space of the chance distribution at a given time is a class of possible worlds. Thanks to this connection between chance and modality, one’s views about modal space can have significant consequences in the theory of chance and can be evaluated in part by how plausible these implications are. I apply this methodology to evaluate certain forms of modal contingentism, the thesis that some facts about what is possible are contingent. Any modal contingentist view that meets certain conditions that I specify generates difficulties in the philosophy of chance, including a problem usually associated with Humeanism that is known as ‘the problem of undermining futures’. I consider two well-known versions of modal contingentism that face this difficulty. The first version, proposed by Hugh Chandler and Nathan Salmon, rests on an argument for the claim that many individuals have their modal features contingently. The second version is motivated by the thesis that the existence of a possible world depends on the existence of the contingent individuals inhabiting it, and that many worlds are therefore contingent existents.

During the last quarter of a century, a number of philosophers have become attracted to the idea that necessity can be analyzed in terms of a hyperintensional notion of essence. One challenge for proponents of this view is to give a plausible explanation of our modal knowledge. The goal of this paper is to develop a strategy for meeting this challenge. My approach rests on an account of modality that I developed in previous work, and which analyzes modal properties in terms of the notion of a metaphysical law. I discuss what information about the metaphysical laws is required for modal knowledge. Moreover, I describe two ways in which we might be able to acquire this information. The first way employs inference to the best explanation. The metaphysical laws, including the essential truths, play a crucial role in causal and grounding explanations and we can gain knowledge of these laws by abductive inferences from facts of which we have perceptual or a priori knowledge. The second way of gaining information about the metaphysical laws rests on knowledge that is partly constitutive of competence with the concepts that are needed to express the relevant information. Finally, I consider how knowledge of the metaphysical laws can be used to establish modal claims, paying special attention to the much-discussed connection between conceiving and possibility.

The Russell-Myhill paradox puts pressure on the Russellian structured view of propositions by showing that it conflicts with certain prima facie attractive ontological and logical principles. I describe several versions of RMP and argue that structurists can appeal to natural assumptions about metaphysical grounding to provide independent reasons for rejecting the ontological principles used in these paradoxes. It remains a task for future work to extend this grounding-based approach to all variants of RMP.

Against the widely affirmed dictum, “all existential statements can be denied without self-contradiction,” this essay argues for some existential statements being necessarily true semantically and thus for transcendental metaphysics in the strict sense. Having briefly reviewed how Ronald Dworkin, Karl-Otto Apel, and Thomas Nagel each affirm the dictum in question and, thereby, imply the possible truth of the statement, “nothing exists,” the essay seeks to show how the statement, “‘nothing exists’ is possibly true”, is pragmatically self-refuting. Against the implications of subjectivity as such, that statement implies the impossibility of knowing any existential statement; that is, knowing what exists or, indeed, whether anything exists is forever denied to us. The dictum is, therefore, itself impossible, and the essay concludes with the assertion that transcendental metaphysics should be neoclassical.

Duncan Pritchard argues that Conee and Feldman have made a mistake by tying their evidentialist views to a classical internalism which accepts the theses of MENT, ACCESS, and DISC. The polar opposite of this classical internalist position is classical externalism, which denies MENT, ACCESS, and DISC. But, Pritchard observes, there are positions intermediate between classical internalism and classical externalism. In particular, there is the epistemic disjunctivist’s position which accepts MENT and ACCESS but denies DISC. Pritchard argues that this disjunctivist position is favorable to the classical internalist position because it provides a better response to skepticism, while overcoming all of the most threatening objections urged against it.

Ever since Darwin people have worried about the sceptical implications of evolution. If our minds are products of evolution like those of other animals, why suppose that the beliefs they produce are true, rather than merely useful? In this chapter we apply this argument to beliefs in three different domains: morality, religion, and science. We identify replies to evolutionary scepticism that work in some domains but not in others. The simplest reply to evolutionary scepticism is that the truth of beliefs in a certain domain is, in fact, connected to evolutionary success, so that evolution can be expected to design systems that produce true beliefs in that domain. We call a connection between truth and evolutionary success a ‘Milvian bridge’, after the tradition which ascribes the triumph of Christianity at the battle of the Milvian bridge to the truth of Christianity. We argue that a Milvian bridge can be constructed for commonsense beliefs, and extended to scientific beliefs, but not to moral and religious beliefs. An alternative reply to evolutionary scepticism, which has been used defend moral beliefs, is to argue that their truth does not depend on their tracking some external state of affairs. We ask if this reply could be used to defend religious beliefs.

Descartes famously states that God could have made any and all of the “eternal truths” that are now in place false. This has led scholars to attribute to Descartes’s God a radical sort of power: the power to do the logically impossible. While Descartes does claim that God could have made any of the eternal truths that are now in place false, I do not think that this commits him to the view that God could have made twice four equal to nine, or anything of that sort. In this paper I show how, by placing Descartes’s doctrine of the eternal truths in its proper historical context, a new and more charitable interpretation of that doctrine becomes available. On this interpretation, Descartes’s God could have made the eternal truths false by choosing not to create the eternal essences to which these truths refer.

Charles S. Peirce argued that, besides deduction and induction, there is a third mode of inference which he called " hypothesis " or " abduction." He characterized abduction as reasoning " from effect to cause," and as " the operation of adopting an explanatory hypothesis." Peirce ' s ideas about abduction, which are related also to historically earlier accounts of heuristic reasoning, have been seen as providing a logic of scientific discovery. Alternatively, abduction is interpreted as giving reasons for pursuing a hypothesis. Inference to the best explanation has also been regarded as an important mode of justification, both in everyday life, detective stories, and science. In particular, scientific realism has been defended by an abductive nomiracle argument, while the critics of realism have attempted to show that this appeal to abduction is question - begging, circular, or incoherent. This paper approaches these issues by distinguishing weaker and stronger forms of abduction, and by showing how these types of inferences can be given Peircean and Bayesian probabilistic reconstructions

In informal terms, abductive reasoning involves inferring the best or most plausible explanation from a given set of facts or data. It is a common occurrence in everyday life and crops up in such diverse places as medical diagnosis, scientific theory formation, accident investigation, language understanding, and jury deliberation. In recent years, it has become a popular and fruitful topic in artificial intelligence research. This volume breaks new ground in the scientific, philosophical, and technological study of abduction. It presents new ideas about inferential and information-processing foundations for knowledge and certainty. The authors argue that knowledge arises from experience by processes of abductive inference, in contrast to the view that it arises non-inferentially, or that deduction and inductive generalization are enough to account for knowledge. Much AI research is hypothetical, so the importance of this book is that it reports key discoveries about abduction that have been made as a result of designing, building, testing, and analyzing actual working knowledge-based systems for medical diagnosis and other abductive tasks. The book tells the story of six generations of increasingly sophisticated generic abduction machines, RED-1, RED-2, PEIRCE, MDX2, TIPS, QUAWDS, and the discovery of reasoning strategies that make it computationally feasible to form well-justified composite explanatory hypotheses, despite the threat of combinatorial explosion. The final chapter argues that perception is logically abductive and presents a layered-abduction computational model of perceptual information processing. This book will be of great interest to researchers in AI, cognitive science, and philosophy of science

This paper posits Peirce’s logical category of abduction as a necessary component in the learning process. Because of the cardinality of categories, Thirdness always contains in itself the Firstness of abduction. In psychological terms, abduction can be interpreted as intuition or insight. The paper suggests that abduction can be modeled as a vector on a complex plane. Such geometrical interpretation of the triadic sign helps to clarify the paradox of new knowledge that haunted us since Plato first articulated it in his Meno dialogue. Some implications for the actual teaching practice are addressed, and the value of practical knowledge affirmed.

Delusional beliefs have sometimes been considered as rational inferences from abnormal experiences. We explore this idea in more detail, making the following points. Firstly, the abnormalities of cognition which initially prompt the entertaining of a delusional belief are not always conscious and since we prefer to restrict the term “experience” to consciousness we refer to “abnormal data” rather than “abnormal experience”. Secondly, we argue that in relation to many delusions (we consider eight) one can clearly identify what the abnormal cognitive data are which prompted the delusion and what the neuropsychological impairment is which is responsible for the occurrence of these data; but one can equally clearly point to cases where this impairments is present but delusion is not. So the impairment is not sufficient for delusion to occur. A second cognitive impairment, one which impairs the ability to evaluate beliefs, must also be present. Thirdly (and this is the main thrust of our chapter) we consider in detail what the nature of the inference is that leads from the abnormal data to the belief. This is not deductive inference and it is not inference by enumerative induction; it is abductive inference. We offer a Bayesian account of abductive inference and apply it to the explanation of delusional belief.

Schurz (Synthese 164:201–234, 2008) proposed a justification of creative abduction on the basis of the Reichenbachian principle of the common cause. In this paper we take up the idea of combining creative abduction with causal principles and model instances of successful creative abduction within a Bayes net framework. We identify necessary conditions for such inferences and investigate their unificatory power. We also sketch several interesting applications of modeling creative abduction Bayesian style. In particular, we discuss use-novel predictions, confirmation, and the problem of underdetermination in the context of abductive inferences.

The moral error theory, it seems, could be true. The mere possibility of its truth might also seem inconsequential. But it is not. For, I argue, there is a sense in which the moral error theory is possible that generates an argument against both non‐cognitivism and moral naturalism. I argue that it is an epistemic possibility that morality is subject to some form of wholesale error of the kind that would make the moral error theory true. Denying this possibility has three unwelcome consequences such that allowing for and explaining it is an adequacy condition on meta‐ethical theories. Non‐cognitivism and moral naturalism, I argue, cannot capture the epistemic possibility of wholesale moral error and so are false. My argument additionally provides independent reason to accept Derek Parfit's claim that if moral non‐naturalism is false then nothing matters. I conclude that whether wholesale moral error is epistemically possible may be, in Richard Rorty's words, ‘one of those issues which puts everything up for grabs at once’ and that even if so, and even if non‐cognitivists and moral naturalists remain unmoved by an argument based upon it, this only helps to highlight the significance of my argument.

Philippa Foot, like others of her philosophical generation, was much concerned with the status and authority of morality. How universal are its demands, and how dependent on the idiosyncrasies of individuals? In the early years of her career, she was persuaded that Kant and his twentieth-century followers had been wrong to insist on the centrality to morality of absolute and unconditionally binding moral imperatives. To that extent, she wrote, there was indeed ‘an element of deception in the official line about morality’. In this paper, I shall explore her early alternative: a system of merely ‘hypothetical’ imperatives, imperatives that depend on the motivations of particular individuals. Could so contingent a system deserve to be termed a morality? How revisionary a proposal was this, and how serious its costs? And how might we reconcile ourselves to a morality stripped of what she called the ‘fictions’ that surrounded it? Foot's early answer, tentative and exploratory, remains of interest, long after she herself abandoned it.

Philosophical arguments usually are and nearly always should be abductive. Across many areas, philosophers are starting to recognize that often the best we can do in theorizing some phenomena is put forward our best overall account of it, warts and all. This is especially true in esoteric areas like logic, aesthetics, mathematics, and morality where the data to be explained is often based in our stubborn intuitions. While this methodological shift is welcome, it's not without problems. Abductive arguments involve significant theoretical resources which themselves can be part of what's being disputed. This means that we will sometimes find otherwise good arguments which suggest their own grounds are problematic. In particular, sometimes revising our beliefs on the basis of such an argument can undermine the very justification we used in that argument. This feature, which I'll call self-effacingness, occurs most dramatically in arguments against our standing views on the esoteric subject matters mentioned above: logic, mathematics, aesthetics, and morality. This is because these subject matters all play a role in how we reason abductively. This isn't an idle fact; we can resist some challenges to our standing beliefs about these subject matters exactly because the challenges are self-effacing. The self-effacing character of certain arguments is thus both a benefit and limitation of the abductive turn and deserves serious attention. I aim to give it the attention it deserves

Either 1. the non-naturalist is in a state of mind that would treat as relevant information about the existence and patterns of non-natural properties and facts as they make up their mind about normative matters, or 2. the non-naturalist is in a state of mind that would treat as irrelevant information about the existence and patterns of non-natural properties and facts as they make up their mind about normative matters. The first state of mind is morally objectionable, for one should not change one’s normative beliefs to pander to the patterns of some non-natural realm. The second state of mind is irrational, for if you think you are aiming to represent non-natural properties correctly, you should be interested to know which actions share a non-natural property and which do not, and you should be prepared to change your mind accordingly.

This paper responds to a recently popular objection to non-naturalist, robust moral realism. The objection is that moral realism is morally objectionable, because realists are committed to taking evidence about the distribution of non-natural properties to be relevant to their first-order moral commitments. I argue that such objections fail. The moral realist is indeed committed to conditionals such as “If there are no non-natural properties, then no action is wrong.” But the realist is not committed to using this conditional in a modus-ponens inference upon coming to believe its antecedent. Placing the discussion in a wider epistemological discussion—here, that of “junk-knowledge”, and of how background knowledge determines the relevance of purported evidence—shows that this objection does not exert a price from the realist.

It has been argued that there is something morally objectionable about moral realism: for instance, according to realism, we are justified in believing that genocide is wrong only if a certain moral fact obtains, but it is objectionable to hold our moral commitments hostage to metaphysics in this way. In this paper, I argue that no version of this moral argument against realism is likely to succeed. More precisely, minimal realism―the kind of realism on which realist theses are understood as internal to moral discourse―is immune to this challenge, contrary to what some proponents of the moral argument have suggested, while robust non-naturalist realists might have good answers to all versions of the argument as well, at least if they adopt a certain stance on how to form metaphysical beliefs in the moral domain.

Non-naturalist realists are committed to the belief, famously voiced by Parfit, that if there are no non-natural facts then nothing matters. But it is morally objectionable to conditionalise all our moral commitments on the question of whether there are non-natural facts. Non-natural facts are causally inefficacious, and so make no difference to the world of our experience. And to be a realist about such facts is to hold that they are mind-independent. It is compatible with our experiences that there are no non-natural facts, or that they are very different from what we think. As Nagel says, realism makes scepticism intelligible. So the non-naturalist must hold that you might be wrong that your partner matters, even if you are correct about every natural, causal fact about your history and relationship. But to hold that conditional attitude to your partner would be a moral betrayal. So believing non-naturalist realism involves doing something immoral.

I seek to promote a fuller understanding of religious skepticism by defending five theses. These concern, respectively: its breadth, discussed in relation to theism on the one hand and naturalism on the other; why it should be distinguished from a general metaphysical skepticism; how it is supported by the consequences of recent cultural evolution, which at the same time enable new and stronger arguments for atheism; the relations it bears to non-doxastic religious faith; and, finally, its curious capacity in certain not uncommon circumstances to take the form of a soft irreligion that is widely approvable—even from a religious perspective.