H.-J. Glock has made important contributions to discussions of rationality, reasons, and rules. This chapter addresses four conceptions of rationality that Glock identifies. One of these conceptions of rationality is that rationality consists in responsiveness to reasons. This chapter goes on to consider the idea that reasons became prominent in normative ethics because of their usefulness in articulating moral pluralism. The final section of the chapter connects reasons and rules and contends that both are ineliminable.

This article develops a logical (or semantic) response to scepticism about the existence of an external world. Specifically, it is argued that any doubt about the existence of an external world can be proved to be false, but whatever appears to be doubt about the existence of an external world that _cannot_ be proved to be false is nonsense, insofar as it must rely on the assertion of something that is logically impossible. The article further suggests that both G. E. (...) Moore and Ludwig Wittgenstein worked towards the same solution but left their work unfinished. (shrink)

We examine the epistemological foundations of a leading technique in the search for evidence of life on exosolar planets. Specifically, we consider the “transit method” for spectroscopic analysis of exoplanet atmospheres, and the practice of treating anomalous chemical compositions of the atmospheres of exosolar planets as indicators of the potential presence of life. We propose a methodology for ranking the anomalousness of atmospheres that uses the mathematical apparatus of support vector machines, and which aims to be agnostic with respect to (...) the particular chemical biosignatures of life. We argue that our approach is justified by an appeal to the “hinge” model of epistemic justification first proposed by as reported by Wittgenstein. We then compare our approach to previous work due to Walker et al. :779–824, 2018) and Cleland :722–729, 2019a; Does ‘life’ have a definition?, Cambridge University Press, New York, 2019b). (shrink)

It is argued that the two main accounts of ignorance in the contemporary literature—in the terms of the lack of knowledge and the lack of true belief—are lacking in key respects. A new way of thinking about ignorance is offered that can accommodate the motivations for both of the standard views, but which in the process also avoids the problems that afflict these proposals. In short, this new account of ignorance incorporates the idea that ignorance essentially involves not just the (...) absence of a certain epistemic good, but also an intellectual failing of inquiry. It is further contended that making sense of this normative dimension to ignorance requires one to situate one’s account of ignorance within a wider epistemic axiology. (shrink)

Some philosophers have argued that Wittgenstein’s hinges, the centrepiece of his book On Certainty, are the “ungrounded ground” on which knowledge rests. It is usually understood by this that hinges provide a foundation for knowledge without being themselves epistemically warranted. In fact, Wittgenstein articulates that hinges lack any truth-value and are neither justified nor unjustified. This inevitably places them wholly outside the categorial framework of JTB epistemology. What I call the “groundlessness interpretation”, inspired by OC 166, understands the fundamental pieces (...) of our cognitive scaffolding this way. The view has been largely successful. I argue that this interpretation is incomplete for two basic reasons: first, it is not based on undisputed evidence; second, by assuming that hinges are committed to reality by epistemic fiat, it looks as if Wittgenstein is asking us to blindly trust them regardless of their actual content. Contrary to this, I argue that Wittgenstein describes hinges as illuminating world-pictures that reflect reality and are answerable to facts in a derivate way. As the book shows, hinges originate in our engagement with reality and, while considered unquestionable, could be challenged, reassessed, and replaced by new ones. This indicates that hinges are both the result of knowledge-acquisition and somewhat continuous with one’s set of beliefs. It follows that hinges are ultimately rational, and so, apt instruments to confront scepticism. (shrink)

This paper critically explores Nuno Venturinha’s discussion of the Wittgensteinian notion of epistemic vertigo in the context of the radical sceptical problematic, at least as that notion has been recently articulated by Duncan Pritchard.

Some philosophers have argued that Wittgenstein’s hinges, the centrepiece of his book On Certainty, are the “ungrounded ground” on which knowledge rests. It is usually understood by this that hinges provide a foundation for knowledge without being themselves epistemically warranted. In fact, Wittgenstein articulates that hinges lack any truth-value and are neither justified nor unjustified. This inevitably places them wholly outside the categorial framework of JTB epistemology. What I call the “groundlessness interpretation”, inspired by OC 166, understands the fundamental pieces (...) of our cognitive scaffolding this way. The view has been largely successful. I argue that this interpretation is incomplete for two basic reasons: first, it is not based on undisputed evidence; second, by assuming that hinges are committed to reality by epistemic fiat, it looks as if Wittgenstein is asking us to blindly trust them regardless of their actual content. Contrary to this, I argue that Wittgenstein describes hinges as illuminating world-pictures that reflect reality and are answerable to facts in a derivate way. As the book shows, hinges originate in our engagement with reality and, while considered unquestionable, could be challenged, reassessed, and replaced by new ones. This indicates that hinges are both the result of knowledge-acquisition and somewhat continuous with one’s set of beliefs. It follows that hinges are ultimately rational, and so, apt instruments to confront scepticism. (shrink)