Epistemic luck and logical necessities: armchair luck revisited

Modal knowledge accounts like sensitivity or safety face a problem when it comes to knowing propositions that are necessarily true because the modal condition is always fulfilled no matter how random the belief forming method is. Pritchard models the anti-luck condition for knowledge in terms of the modal principle safety. Thus, his anti-luck epistemology faces the same problem when it comes to logical necessities. Any belief in a proposition that is necessarily true fulfills the anti-luck condition and, therefore, qualifies as knowledge. Miščević shares Pritchard’s take on epistemic luck and acknowledges the resulting problem. In his intriguing article “Armchair Luck: Apriority, Intellection and Epistemic Luck” Miščević suggests solving the problem by supplementing safety with a virtue theoretic condition-“agent stability”-which he also spells out in modal terms. I will argue that Miščević is on the right track when he suggests adding a virtue-theoretic component to the safety condition. However, it should not be specified modally but rather in terms of performances that manifest competences

Knowing and Checking: An Epistemological Investigation

This book is primarily about checking and only derivatively about knowing. Checking is a very common concept for describing a subject’s epistemic goals and actions. Surprisingly, there has been no philosophical attention paid to the notion of checking. In Part I, I develop a sensitivity account of checking. To be more explicit, I analyze the internalist and externalist components of the epistemic action of checking which include the intentions of the checking subject and the necessary externalist features of the method used. Crucially, successfully checking whether p is true requires using a method that is sensitive with respect to p, i.e. a method that would not indicate that p, if p were false. In Part II, I use the distinction between knowing and checking to explain central puzzles about knowledge, particularly puzzles centering on knowledge closure, puzzles concerning bootstrapping and the skeptical puzzle. Moreover, the book clarifies a dispute about modal epistemology, concerning the application of the sensitivity principle. By arguing that sensitivity is necessary for checking but not knowing, I explain where our persisting intuitions about sensitivity have their place in epistemology

Block-Simultaneous Direction Method of Multipliers: A proximal primal-dual splitting algorithm for nonconvex problems with multiple constraints

We introduce a generalization of the linearized Alternating Direction Method of Multipliers to optimize a real-valued function $f$ of multiple arguments with potentially multiple constraints $g_\circ$ on each of them. The function $f$ may be nonconvex as long as it is convex in every argument, while the constraints $g_\circ$ need to be convex but not smooth. If $f$ is smooth, the proposed Block-Simultaneous Direction Method of Multipliers (bSDMM) can be interpreted as a proximal analog to inexact coordinate descent methods under constraints. Unlike alternative approaches for joint solvers of multiple-constraint problems, we do not require linear operators $L$ of a constraint function $g(L\ \cdot)$ to be invertible or linked between each other. bSDMM is well-suited for a range of optimization problems, in particular for data analysis, where $f$ is the likelihood function of a model and $L$ could be a transformation matrix describing e.g. finite differences or basis transforms. We apply bSDMM to the Non-negative Matrix Factorization task of a hyperspectral unmixing problem and demonstrate convergence and effectiveness of multiple constraints on both matrix factors. The algorithms are implemented in python and released as an open-source package.Comment: 13 pages, 4 figure