What Does Knowledge-Yielding Deduction Require of Its Premises?

Synthese , 2013

The idea that knowledge can be extended by inference from what is known seems highly plausible. Yet, as shown by familiar preface paradox and lottery-type cases, the possibility of aggregating uncertainty casts doubt on its tenability. We show that these considerations go much further than previously recognized and significantly restrict the kinds of closure ordinary theories of knowledge can endorse. Meeting the challenge of uncertainty aggregation requires either the restriction of knowledge-extending inferences to single premises, or eliminating epistemic uncertainty in known premises. The first strategy, while effective, retains little of the original idea—conclusions even of modus ponens inferences from known premises are not always known. We then look at the second strategy, inspecting the most elaborate and promising attempt to secure the epistemic role of basic inferences, namely Timothy Williamson’s safety theory of knowledge. We argue that while it indeed has the merit of allowing basic inferences such as modus ponens to extend knowledge, Williamson’s theory faces formidable difficulties. These difficulties, moreover, arise from the very feature responsible for its virtue- the infallibilism of knowledge.

A novel argument is offered against the following popular condition on inferential knowledge: a person inferentially knows a conclusion only if they know each of the claims from which they essentially inferred that conclusion. The epistemology of conditional proof reveals that we sometimes come to know conditionals by inferring them from assumptions rather than beliefs. Since knowledge requires belief, cases of knowing via conditional proof refute the popular knowledge from knowledge condition. It also suggests more radical cases against the condition and it brings to light the underrecognized category of inferential basic knowledge.

Veritas (Porto Alegre), 2017

The knowledge from falsehood (KFF) advocates present us with putative examples of inferential knowledge in which a subject S apparently acquires knowledge by competently inferring it from a falsehood. If they are right, then we will have to face some major problems for the epistemology of reasoning. However, in this paper, I will argue that there is no knowledge from falsehood (KFF), that the cases presented by KFF advocates are not cases of genuine inferential knowledge at all, and that the intuitive reaction to attribute knowledge to the subject in such cases has no relation with the falsehood. My opposition to KFF will be directed to the KFF account put forward by Peter Klein in his paper "Useful False Beliefs" (2008). In particular, I show that Klein's account fails because (i) it is unable to describe how the falsehood can inferentially provide a positive epistemic status to the inferred belief in order to upgrade it to knowledge; and (ii) it is incompatible with a tacit and widespread notion of inference.

Philosophical Writings, 2014

It is largely admitted that the tripartite conception as Justified True Belief knowledge implying truth is possible but truth is not recognisable per se, that is, knowledge implying self-awareness of having the truth (which is not to be conflated with certainty) is impossible. Borrowing from the theory of meaning I intend to redefine knowledge with the immanence principle and the implicitness principle, which impose the recognisability of the knowledge conditions. Second, I argue that since truth is not directly recognisable it must be inferred. Hence, knowledge is the product of an inference from a belief and a justification to the truthascription of the henceforth-acknowledged belief. The seminal Gettier problems take thus an almost trivial aspect, or at least it is no obstacle to the possibility of knowledge thus defined.

Philosophical Studies, 2012

Claims of the form 'I know P and it might be that not-P' tend to sound odd. One natural explanation of this oddity is that the conjuncts are semantically incompatible: in its core epistemic use, 'Might P' is true in a speaker's mouth only if the speaker does not know that not-P. In this paper I defend this view against an alternative proposal that has been advocated by Trent Dougherty and Patrick Rysiew and elaborated upon in Jeremy Fantl and Matthew McGrath's recent Knowledge in an Uncertain World.

The central venture I undertake in this paper is twofold: I set out to defend the traditional definition of knowledge as justified true belief [afterwards, the JTB account]; similarly, I proceed to grant it a structure that secures it against the objections laid against it-specifically, the Gettier Problem and its alternatives [Feldman's Havit Case and Chisholm's 'sheep in the field']. Furthermore, I provide a treatment of the strict justification condition: namely, that 'if X could not have been aware of false premises, then X cannot know anything'. It is this treatment that spurs my hypothetical model of knowledge as JTB devoid of contradictory evidence for X.

We often think of a logic as a three-part system composed of an uninterpreted language, a semantic system, and a deductive system. Keeping the language fixed, different logics can be produced by changing the semantic system or the deductive system or both. Choosing a logic is not just a matter of convenience. Although two logics that differ only in deductive system can be equivalent in the sense of always deriving the same conclusions from the same premises, it is often true that each system corresponds to a specific approach to logic. Natural deduction, specifically, corresponds to approaching logic as a mathematical model of correct deductive reasoning. In natural deduction, the flow of reasoning is not just a linear sequencing in which each formula in each step is derived just from its previous lines. Rather, natural deduction involves, in addition to steps derived just from their previous lines, also steps derived from subderivations that may contain further subderivations, each subderivation starting from a supposition. In natural deduction, the actual deductive process is more explicitly analyzed than in other deductive systems—with the same language and semantic system. This paper also investigates some consequences of understanding natural-deduction systems in an epistemological framework.

Knowledge-First: Approaches in Epistemology and Mind, J. Adam Carter, Emma Gordon & Benjamin Jarvis (eds.) , 2017

Since the publication of Timothy Williamson’s Knowledge and its Limits, knowledge-first epistemology has become increasingly influential within epistemology. This paper discusses the viability of the knowledge-first program. The paper has two main parts. In the first part, I briefly present knowledge-first epistemology as well as several big picture reasons for concern about this program. While this considerations are pressing, I concede, however, that they are not conclusive. To determine the viability of knowledge-first epistemology will require philosophers to carefully evaluate the individual theses endorsed by knowledge-first epistemologists as well as to compare it with alternative packages of views. In the second part of the paper, I contribute to this evaluation by considering a specific thesis endorsed by many knowledge-first epistemologists – the knowledge norm of assertion. According to this norm, roughly speaking, one should assert that p only if one knows that p. I present and motivate this thesis. I then turn to a familiar concern with the norm: In many cases, it is intuitively appropriate for someone who has a strongly justified belief that p, but who doesn't know that p, to assert that p. Proponents of the knowledge norm of assertion typically explain away our judgments about such cases by arguing that the relevant assertion is improper but that the subject has an excuse and is therefore not blameworthy for making the assertion. I argue that that this response does not work. In many of the problem cases, it is not merely that the subject’s assertion is blameless. Rather, the subject positively ought to make the assertion. Appealing to an excuse cannot be used to adequately explain this fact. (Nor can we explain this fact by appealing to some other, quite different, consideration.) Finally, I conclude by briefly considering whether we should replace the knowledge norm of assertion with an alternative norm. I argue that the most plausible view is that there is no norm specifically tied to assertion.