Causal necessity typically receives only oblique attention. Causal relations, laws of nature, counterfactual conditionals, or dispositions are usually the immediate subject(s) of interest. All of these, however, have a common feature. In some way, they involve the causal modality, some form of natural or physical necessity. In this paper, causal necessity is discussed with the purpose of determining whether a completely general empiricist theory can account for the causal in terms of the noncausal. Based on an examination of causal relations, (...) laws of nature, counterfactual conditionals, and dispositions, it is argued that no reductive program devoid of essentialist commitments can account for all the phenomena that involve causal necessity. Hence, neo-Humean empiricism fails to provide a framework adequate for understanding causal necessity. (shrink)

The paper argues that knowledge is not closed under logical inference. The argument proceeds from the openness of evidential support and the dependence of empirical knowledge on evidence, to the conclusion that knowledge is open. Without attempting to provide a full-fledged theory of evidence, we show that on the modest assumption that evidence cannot support both a proposition and its negation, or, alternatively, that information that reduces the probability of a proposition cannot constitute evidence for its truth, the relation of (...) evidential support is not closed under known entailment. Therefore the evidence-for relation is deductively open regardless of whether evidence is probabilistic or not. Given even a weak dependence of empirical knowledge on evidence, we argue that empirical knowledge is also open. On this basis, we also respond to the strongest argument in support of knowledge closure. Finally, we present a number of significant benefits of our position, namely, offering a unified explanation for a range of epistemological puzzles. (shrink)

In the marketplace of opinions concerning the metaphysics of mind and consciousness panqualityism (PQ) occupies an interesting position. It is a distinct variant of neutral monism, as well as of protophenomenalism, and as such it strives to carve out a conceptual niche midway between physicalism and mentalism. It is also a brand of Russellian monism, advocated by its supporters as a less costly and less extravagant alternative to panpsychism. Being clearly articulated and relatively well-developed it constitutes an intriguing view. Nonetheless, (...) the present paper takes a decisively critical stance towards PQ. In particular, it challenges it on two principal grounds. First, I argue that PQ's analysis of experience, and of the qualities tasked with constituting the phenomenal character of experience, is fundamentally flawed. Second, I argue that PQ's attempt to explain phenomenal consciousness as a function of reflective awareness is equally misguided. Along the way, the paper also points the shortcomings of previously established critiques of PQ. All in all, the discussion identifies some difficulties that are likely to generalize beyond PQ's specific circumstances, raising concerns regarding the viability of a "middle of the road" solution to the mind–body problem. (shrink)

Harman and Lewis credit Kripke with having formulated a puzzle that seems to show that knowledge entails dogmatism. The puzzle is widely regarded as having been solved. In this paper we argue that this standard solution, in its various versions, addresses only a limited aspect of the puzzle and holds no promise of fully resolving it. Analyzing this failure and the proper rendering of the puzzle, it is suggested that it poses a significant challenge for the defense of epistemic closure.

In this paper, I defend the view that any good account of the logical form of thought experiments should contain a conditional. Moreover, there are some reasons to think it should be a counterfactual conditional. First, I defend Williamson’s account of the logical form of thought experiments against a competing account offered by Ichikawa and Jarvis. The two accounts have a similar structure, but Williamson’s posits a counterfactual conditional where Ichikawa and Jarvis’ posits a strict conditional. Williamson’s motivation is related (...) to the problem of deviant realizations, and Ichikawa and Jarvis propose to take care of this problem by enriching the content of the thought experiment in the way we enrich the content of a text of fiction. However, this sort of enrichment is also compatible with Williamson’s account. I then consider a different view, defended by Malmgren, on which a complex possibility claim exhausts our reasoning on typical thought experiments. I argue that this account, leaving out a conditional, fails to represent an important part of our reasoning with thought experiments. This is brought out by reflection on the relationship between thought experiments and similar actual cases and by reflection on the requirement, formulated by Malmgren herself, that our reasoning should have an adequate level of generality. (shrink)

What psychological and philosophical significance should we attach to recent efforts at computer simulations of human cognitive capacities? In answering this question, I find it useful to distinguish what I will call "strong" AI from "weak" or "cautious" AI. According to weak AI, the principal value of the computer in the study of the mind is that it gives us a very powerful tool. For example, it enables us to formulate and test hypotheses in a more rigorous and precise fashion. (...) But according to strong AI, the computer is not merely a tool in the study of the mind; rather, the appropriately programmed computer really is a mind, in the sense that computers given the right programs can be literally said to. (shrink)

Properly understood, foundationalism as a meta‐epistemic theory is consistent with skepticism. This article outlines five possible points of overlap between the two views, and shows that arguments against foundationalism posited on its inability to refute skepticism are improperly framed.

I argue that property dualists cannot hold that minds are physical substances. The focus of my discussion is a property dualism that takes qualia to be sui generis features of reality.

Properties come in clusters. It seems impossible, for instance, that a mass could float free, unattached to any other property. David Armstrong takes this as a reductio of the bundle theory and an argument for substrata, while Peter Simons and Arda Denkel reply by supplementing the bundle theory with accounts of property interdependencies. I argue against both views. Virtually all plausible ontologies turn out to be committed to the existence of free masses.

What makes an object the same persisting individual over time? Philosophers and psychologists have both grappled with this question, but from different perspectives—philosophers conceptually analyzing the criteria for object persistence, and psychologists exploring the mental mechanisms that lead us to experience the world in terms of persisting objects. It is striking that the same themes populate explorations of persistence in these two very different fields—e.g. the roles of spatiotemporal continuity, persistence through property change, and cohesion violations. Such similarities may reflect (...) an underlying connection, in that psychological mechanisms of object persistence (especially relevant parts of mid-level visual object processing) may serve to underlie the intuitions about persistence that fuel metaphysical theories. This would be a way for cognitive science to join these two disparate fields, helping to explain the possible origins and reliability of some metaphysical intuitions, and perhaps leading to philosophical progress. (shrink)

Most answers to the mind-body problem are claims about the nature of mental properties and substances. But advocates of non-reductive physicalism have generally neglected the topic of the nature of substance, quickly nodding to the view that all substances are physical, while focusing their intellectual energy on understanding how mental properties relate to physical ones. Let us call the view that all substances are physical or are exhaustively composed of physical substances substance physicalism (SP). Herein, I argue that non-reductive physicalism (...) (NRP) cannot uphold substance physicalism and is thereby false. For NRP faces a mind problem: its commitment to property irreducibility prevents that which bears the mental properties—the mind, or on some views, the self or person—from being a physical thing. (shrink)

Sydney Shoemaker's "Subset Account" offers a new take on determinable properties and the realization relation as well as a defense of non-reductive physicalism from the problem of mental causation. At the heart of this account are the claims that (1) mental properties are determinable properties and (2) the causal powers that individuate a determinable property are a proper subset of the causal powers that individuate the determinates of that property. The second claim, however, has led to the accusation that the (...) effects caused by the instantiation of a determinable property will also be caused by the instantiation of the determinates of that property—so instead of solving the problem of mental causation, the Subset Account ends up guaranteeing that the effects of mental properties (and all other types of determinable property) will be causally overdetermined! In this paper, I explore this objection. I argue that both sides in this debate have failed to engage the question at the heart of the objection: Given that both a determinable property and its determinates have the power to cause some effect (E), does it follow that both will actually cause E when the relevant conditions obtain? To make genuine progress towards answering this question, we need to take a serious look at the metaphysics of causation. With the debate properly reframed and issues about the metaphysics of causation front and center, I explore the question of whether the Subset Account is doomed to result in problematic causal overdetermination. (shrink)

The debate over the objects of episodic memory has for some time been stalled, with few alternatives to familiar forms of direct and indirect realism being advanced. This paper moves the debate forward by building on insights from the recent psychological literature on memory as a form of episodic hypothetical thought (or mental time travel) and the recent philosophical literature on relationalist and representationalist approaches to perception. The former suggests that an adequate account of the objects of episodic memory will (...) have to be a special case of an account of the objects of episodic hypothetical thought more generally. The latter suggests that an adequate account of the objects of episodic hypothetical thought will have to combine features of direct realism and representationalism. We develop a novel pragmatist-inspired account of the objects of episodic hypothetical thought that has the requisite features. (shrink)

According to Russo and Williamson (Int Stud Philos Sci 21(2):157–170, 2007, Hist Philos Life Sci 33:389–396, 2011a, Philos Sci 1(1):47–69, 2011b ), in order to establish a causal claim of the form, ‘_C_ is a cause of _E_’, one typically needs evidence that there is an underlying mechanism between _C_ and _E_ as well as evidence that _C_ makes a difference to _E_. This thesis has been used to argue that hierarchies of evidence, as championed by evidence-based movements, tend to (...) give primacy to evidence of difference making over evidence of mechanisms and are flawed because the two sorts of evidence are required and they should be treated on a par. An alternative approach gives primacy to evidence of mechanism over evidence of difference making. In this paper, we argue that this alternative approach is equally flawed, again because both sorts of evidence need to be treated on a par. As an illustration of this parity, we explain how scientists working in the ‘EnviroGenomarkers’ project constantly make use of the two evidential components in a dynamic and intertwined way. We argue that such an interplay is needed not only for causal assessment but also for policy purposes. (shrink)

The paper seeks a perfectly general argument regarding the non-contingent limits to any (human or non-human) knowledge. After expressing disappointment with the history of philosophy on this score, an argument is grounded in Fitch’s proof, which demonstrates the unknowability of some truths. The necessity of this unknowability is then defended by arguing for the necessity of Fitch’s premise—viz., there this is in fact some ignorance.

In this article I construe Russell's definite description notation as a fragment of an "ideal language"– a language in which, as Russell puts it in the "Logical Atomism" lectures, "the words in a proposition correspond one by one with the components of the corresponding fact." Russell's notation – containing as it does variables, quantifiers and the identity sign – commits him to an ontology that is lavish indeed. It thus conflicts with the spirit of the theory of descriptions, which is (...) developed in the service of ontological frugality. I make use of arguments derived from the Tractatus to show that an ideal language need not contain logical signs. I thus defend the spirit of the theory of descriptions while departing from its letter. (shrink)

This paper examines tracer techniques in neuroscience, which are used to identify neural connections in the brain and nervous system. These connections capture a type of “structural connectivity” that is expected to inform our understanding of the functional nature of these tissues. This is due to the fact that neural connectivity constrains the flow of signal propagation, which is a type of causal process in neurons. This work explores how tracers are used to identify causal information, what standards they are (...) expected to meet, the forms of causal information they provide, and how an analysis of these techniques contributes to the philosophical literature, in particular, the literature on mark transmission and mechanistic accounts of causation. (shrink)

Recent philosophical work on causation has focused on distinctions across types of causal relationships. This paper argues for another distinction that has yet to receive attention in this work. This distinction has to do with whether causal relationships have “material continuity,” which refers to the reliable movement of material from cause to effect. This paper provides an analysis of material continuity and argues that causal relationships with this feature are associated with a unique explanatory perspective, are studied with distinct causal (...) investigative methods, and provide different types of causal control over their effects. (shrink)

Baron Reed has developed a new argument for skepticism: (1) contemporary epistemologists are all committed to two theses, fallibilism and attributabilism; unfortunately, (2) these two theses about knowledge are incompatible; therefore, (3) knowledge as conceived by contemporary epistemologists is impossible. In this brief paper I suggest that Reed's argument appears to rest on an understanding of attributabilism that is so strong (call it maximal attributabilism) that it's doubtful that many contemporary epistemologists actually embrace it. Nor does Reed offer any direct (...) argument for the truth of maximal attributabilism. Therefore, we need not be persuaded by Reed's new argument for skepticism. (shrink)

Take the following version of scientific realism: we have good reason to believe that (some of the) current scientific theories tell us something specific about the underlying, i.e. unobservable, structures of the world, for instance that there are electrons with a certain electric charge, or that there are viruses that cause certain diseases. Popper, the rationalist, would not have adhered to the proposed formulation of scientific realism in terms of the rationality of existential beliefs concerning unobservables. Popper did not believe (...) in belief. According to Van Fraassen, the empiricist, one may yet have a rational existential belief concerning unobservables, given a liberal notion of rationality of belief. In this paper I will investigate to what extent a reassessment of both Popper’s rejection of the rationality of belief and Van Fraassen’s reformulation of the rationality of belief, points towards a new and pragmatist dissolution of the ‘problem of scientific realism’. (shrink)

Although recent epistemology has been marked by several prominent disagreements – e.g., between foundationalists and coherentists, internalists and externalists – there has been widespread agreement that some form of fallibilism must be correct. According to a rough formulation of this view, it is possible for a subject to have knowledge even in cases where the justification or grounding for the knowledge is compatible with the subject’s being mistaken. In this paper, I examine the motivation for fallibilism before providing a fully (...) general account of the view. I conclude by looking at the two major difficulties for fallibilism: the Gettier problem and the lottery paradox. (shrink)

The traditional argument for skepticism relies on a comparison between a normal subject and a subject in a skeptical scenario: because there is no relevant difference between them, neither has knowledge. Externalists respond by arguing that there is in fact a relevant difference—the normal subject is properly situated in her environment. I argue, however, that there is another sort of comparison available—one between a normal subject and a subject with a belief that is accidentally true—that makes possible a new argument (...) for skepticism. Unlike the traditional form of skeptical argument, this new argument applies equally well to both internalist and externalist theories of knowledge. (shrink)

Extending work of Wittgenstein, Lakoff and Johnson I suggest that it is the metaphors we rely on in order to conceptualise time that provide an illusory space for time-travel-talk. For example, in the “Moving Time” spatialisation of time, “objects” move past the agent from the future to the past. The objects all move in the same direction – this is mapped to time always moving in the same direction. But then it is easy to imagine suspending this rule, and asking (...) why the objects should not start moving in the opposite direction. This is one way of generating the idea of time-travel “back” into the past. Time-travel-talk essentially involves the unaware projection of fragments of our time-talk – taken from powerful conceptual metaphors – onto the nature of reality itself. Understanding this dissolves away the charm and attractions of such talk. (shrink)

The recent movement towards virtue–theoretic treatments of epistemological concepts can be understood in terms of the desire to eliminate epistemic luck. Significantly, however, it is argued that the two main varieties of virtue epistemology are responding to different types of epistemic luck. In particular, whilst proponents of reliabilism–based virtue theories have been focusing on the problem of what I call “veritic” epistemic luck, non–reliabilism–based virtue theories have instead been concerned with a very different type of epistemic luck, what I call (...) “reflective” epistemic luck. It is argued that, prima facie at least, both forms of epistemic luck need to be responded to by any adequate epistemological theory. The problem, however, is that one can best eliminate veritic epistemic luck by adducing a so–called safety–based epistemological theory that need not be allied to a virtue–based account, and there is no fully adequate way of eliminating reflective epistemic luck. I thus conclude that this raises a fundamental difficulty for virtue–based epistemological theories, on either construal. [ABSTRACT FROM AUTHOR]. (shrink)

A commonly expressed worry in the contemporary literature on the problem of epistemological scepticism is that there is something deeply intellectually unsatisfying about the dominant anti-sceptical theories. In this paper I outline the main approaches to scepticism and argue that they each fail to capture what is essential to the sceptical challenge because they fail to fully understand the role that the problem of epistemic luck plays in that challenge. I further argue that scepticism is best thought of not as (...) a quandary directed at our possession of knowledge simpliciter, but rather as concerned with a specific kind of knowledge that is epistemically desirable. On this view, the source of scepticism lies in a peculiarly epistemic form of angst. It is always by favour of Nature that one knows something. [Wittgenstein 1969: §505]. (shrink)

The aim of this paper is to look at what a parallel deflationist program might be in the theory of knowledge and examine its prospect. In what follows I will simplify matters slightly by focussing on empirical knowledge rather than knowledge in general, though most of what I have to say ought to be applicable, mutatis mutandis, to knowledge in general. Moreover,note that it is not my aim to offer a full defense of a particular deflationist theory of knowledge, which (...) would go well beyond the scope of this paper, but only to defend the utility of taking the deflationist program as regards the theory of knowledge seriously by showing that there is a plausible deflationist position available that is worthy of further scrutiny. (shrink)

The growing literature on philosophical thought experiments has so far focused almost exclusively on the role of thought experiments in confirming or refuting philosophical hypotheses or theories. In this paper we draw attention to an additional and largely ignored role that thought experiments frequently play in our philosophical practice: some thought experiments do not merely serve as means for testing various philosophical hypotheses or theories, but also serve as facilitators for conceiving and articulating new ones. As we will put it, (...) they serve as ‘heuristics for theory discovery’. Our purpose in the paper is two-fold: to make a case that this additional role of thought experiments deserves the attention of philosophers interested in the methodology of philosophy; to sketch a tentative taxonomy of a number of distinct ways in which philosophical thought experiments can aid theory discovery, which can guide future research on this role of thought experiments. (shrink)

In an environment characterized by the emergence of new and diverse (and often opposed) philosophical efforts, there is a need for a conception of philosophy that will promote the exchange and critical consideration of divergent insights. Depending upon the operative conception, philosophical efforts can be viewed as significant, insightful and instructive, or unimportant, misguided and not real philosophy. This paper develops John Dewey's conception of philosophy as a mode of inquiry in contrast with Bertrand Russell's conception of philosophy as a (...) mode of analysis. I argue that while Russell's analytic conception of philosophy justifies the dismissal of non-analytic philosophies, Dewey's conception of philosophy provides a theoretical framework for the comparison, evaluation and interaction of alternatives. (shrink)

We seem to directly perceive external things. But can we? According to the time‐lag argument, we cannot. What we directly perceive happens now. There is a time‐lag between our perceptions and the external things we seem to directly perceive; these external things happen in the past; thus, what we directly perceive must be something else, for example, sense‐data, and we can only at best indirectly perceive other things. This paper examines the time‐lag argument given contemporary metaphysics. I argue that this (...) argument is not as compelling as it may initially seem. First, it denies that what we directly perceive can ever be what it seems to be; second, it conflicts with the current physical conception of time, relativity theory. This latter point leads to a more general one: the argument's force depends on a particular metaphysical conception on time, presentism, which is controversial in contemporary metaphysics of time. Given the alternative conception, eternalism, the argument is much less compelling. The overall argument of this paper, then, is that, if one wishes to hold that we directly perceive external things, we should subscribe to the latter view of time, i.e., eternalism. (shrink)

Since Darwin, the idea of psychological continuity between humans and other animals has dominated theory and research in investigating the minds of other species. Indeed, the field of comparative psychology was founded on two assumptions. First, it was assumed that introspection could provide humans with reliable knowledge about the causal connection between specific mental states and specific behaviors. Second, it was assumed that in those cases in which other species exhibited behaviors similar to our own, similar psychological causes were at (...) work. In this paper, we show how this argument by analogy is flawed with respect to the case of second‐order mental states. As a test case, we focus on the question of how other species conceive of visual attention, and in particular whether chimpanzees interpret seeing as a mentalistic event involving internal states of perception, attention, and belief. We conclude that chimpanzees do not reason about seeing in this manner, and indeed, there is considerable reason to suppose that they do not harbor representations of mental states in general. We propose a reinterpretation model in which the majority of the rich social behaviors that humans and other primates share in common emerged long before the human lineage evolved the psychological means of interpreting those behaviors in mentalistic terms. Although humans, chimpanzees, and most other species may be said to possess mental states, humans alone may have evolved a cognitive specialization for reasoning about such states. (shrink)

In concrete applications of probability, statistical investigation gives us knowledge of some probabilities, but we generally want to know many others that are not directly revealed by our data. For instance, we may know prob(P/Q) (the probability of P given Q) and prob(P/R), but what we really want is prob(P/Q& R), and we may not have the data required to assess that directly. The probability calculus is of no help here. Given prob(P/Q) and prob(P/R), it is consistent with the probability (...) calculus for prob(P/Q& R) to have any value between 0 and 1. Is there any way to make a reasonable estimate of the value of prob(P/Q& R) 1 A related problem occurs when probability practitioners adopt undefended assumptions of statistical independence simply on the basis of not seeing any connection between two propositions. This is common practice, but its justification has eluded probability theorists, and researchers are typically apologetic about making such assumptions. Is there any way to defend the practice? This paper shows that on a certain conception of probability—nomic probability—there are principles of "probable probabilities" that license inferences of the above sort. These are principles telling us that although certain inferences from probabilities to probabilities are not deductively valid, nevertheless the second-order probability of their yielding correct results is 1. This makes it defeasibly reasonable to make the inferences. Thus I argue that it is defeasibly reasonable to assume statistical independence when we have no information to the contrary. And I show that there is a function Y(r, s, a) such that if prob(P/Q) = r, prob(P/R) = s, andprob(P/U) = a (where U is our background knowledge) then it is defeasibly reasonable to expect that prob(P/Q&R) = Y(r, s, a). Numerous other defeasible inferences are licensed by similar principles of probable probabilities. This has the potential to greatly enhance the usefulness of probabilities in practical application. (shrink)

It is widely believed that one should not become more confident that all swans are white and all lions are brave simply by observing white swans. Irrelevant conjunction or “tacking” of a theory onto another is often thought problematic for Bayesianism, especially given the ratio measure of confirmation considered here. It is recalled that the irrelevant conjunct is not confirmed at all. Using the ratio measure, the irrelevant conjunction is confirmed to the same degree as the relevant conjunct, which, it (...) is argued, is ideal: the irrelevant conjunct is irrelevant. Because the past’s really having been as it now appears to have been is an irrelevant conjunct, present evidence confirms theories about past events only insofar as irrelevant conjunctions are confirmed. Hence the ideal of not confirming irrelevant conjunctions would imply that historical claims are not confirmed. Confirmation measures partially realizing that ideal make the confirmation of historical claims by present evidence depend strongly on the (presumably subjective) degree of belief in the irrelevant conjunct. The unusually good behavior of the ratio measure has a bearing on the problem of measure sensitivity. For non-statistical hypotheses, Bayes’ theorem yields a fractional linear transformation in the prior probability, not a linear rescaling, so even the ratio measure arguably does not aptly measure confirmation in such cases. (shrink)

According to David Lewis, the predicate ‘knows’ is context-sensitive in the sense that its truth conditions vary across conversational contexts, which stretch or compress the domain of error possibilities to be eliminated by the subject’s evidence. Our concern in this paper is to thematize, assess, and overcome within a neo-Lewisian contextualist project two important mismatches between our use of ‘know’ in ordinary life and the use of ‘know’ by ‘Lewisian’ ordinary speakers. The first mismatch is that Lewisian contextualism still overgenerates (...) the error possibilities which cannot be ignored in a given context, since it is oblivious to the distinction between ‘invented’ and ‘discovered’ possibilities. The second mismatch is a full-scale one: an adequate account of knowledge attribution is not exhausted by the subject’s negative capacity of pruning branches off the tree of counterpossibilities. We therefore introduce a new vector of value, which explains how ‘know’ comes in degrees: the satisfaction of ‘know better’ is made to depend on the capacity of imagining possibilities connected in a relevant way with the subject’s beliefs. (shrink)

Cognition is not, and could not possibly be, entirely representational in character. There is also a phenomenal form of cognitive expression that registers the intrinsic properties of mental states themselves. Arguments against the reality of this intrinsic phenomenal dimension to mental experience have focused either on its supposed impossibility, or secondly, the non-appearance of any such qualities to introspection. This paper argues to the contrary, that the registration of cognitive state properties does take place independently of representational content; and necessarily (...) so, since it supports an independent function—self-management. Given the fact that unlike a computer, the brain must, of necessity, operate itself, it needs to be in touch with itself to do so. Intrinsic phenomenal forms of cognitive expression allow the brain to do just that by registering characteristics of the cognitive states themselves. Self-management might well prove to constitute the prime reason for the emergence of subjectivity itself. (shrink)

Aristotle’s solution to Zeno’s arrow paradox differs markedly from the so called at-at solution championed by Russell, which has become the orthodox view in contemporary philosophy. The latter supposes that motion consists in simply being at different places at different times. It can boast parsimony because it eliminates velocity from the ontology. Aristotle, by contrast, solves the paradox by denying that the flight of the arrow is composed of instants; rather, on my reading, he holds that the flight is a (...) unity which is ontologically prior to the temporal parts that may be abstracted from it. I label this position temporal holism; and an entity that is ontological prior to its temporal parts lasting. Lasting, I argue, is the key to Aristotle’s solution to the arrow paradox, but it has received insufficient attention in the relevant literature. I therefore set out here to investigate lasting and highlight its major role in Aristotle’s metaphysics more broadly, and in his solution to other problems of change. I show, too, how lasting within a contemporary context underwrites a parsimonious and intuitive solution to the arrow paradox that retains instantaneous velocity, and hence solves a problem for those who think velocity is required within the ontology to underwrite certain causal roles. (shrink)

From 1929 onwards, C. I. Lewis defended the foundationalist claim that judgements of the form 'x is probable' only make sense if one assumes there to be a ground y that is certain (where x and y may be beliefs, propositions, or events). Without this assumption, Lewis argues, the probability of x could not be anything other than zero. Hans Reichenbach repeatedly contested Lewis's idea, calling it "a remnant of rationalism". The last move in this debate was a challenge by (...) Lewis, defying Reichenbach to produce a regress of probability values that yields a number other than zero. Reichenbach never took up the challenge, but we will meet it on his behalf, as it were. By presenting a series converging to a limit, we demonstrate that x can have a definite and computable probability, even if its justification consists of an infinite number of steps. Next we show the invalidity of a recent riposte of foundationalists that this limit of the series can be the ground of justification. Finally we discuss the question where justification can come from if not from a ground. (shrink)