It is widely agreed that contraposition, strengthening the antecedent and hypothetical syllogism fail for subjunctive conditionals. The following putative counter-examples are frequently cited, respectively.

In Counterfactual Conditionals, Daniel Dohrn discusses the standard account of counterfactuals, conditionals of the form ‘If A had been the case, then B would have been the case’. According to the standard account, a counterfactual is true if the then-sentence is true in all closest worlds in which the if-sentence is true. Closeness is spelled out in terms of an ordering of worlds by their similarity. Dohrn explores resources of defending the standard account against several challenges. In particular, he defends (...) the standard logics for counterfactuals. He discusses exemplary doubts as to whether conditionals have truth conditions. He inquires into the interaction between truth and probability of counterfactuals. He tackles problems with the similarity ordering. He address the interaction between counterfactuals and normalcy conditions. He closes with elaborating peculiarities of future-directed counterfactuals. (shrink)

Moti Mizrahi (2013) presents some novel counterexamples to Hypothetical Syllogism (HS) for indicative conditionals. I show that they are not compelling as they neglect the complicated ways in which conditionals and modals interact. I then briefly outline why HS should nevertheless be rejected.

The debate over Hypothetical Syllogism is locked in stalemate. Although putative natural language counterexamples to Hypothetical Syllogism abound, many philosophers defend Hypothetical Syllogism, arguing that the alleged counterexamples involve an illicit shift in context. The proper lesson to draw from the putative counterexamples, they argue, is that natural language conditionals are context-sensitive conditionals which obey Hypothetical Syllogism. In order to make progress on the issue, I consider and improve upon Morreau’s proof of the invalidity of Hypothetical Syllogism. The improved proof (...) relies upon the semantic claim that conditionals with antecedents irrelevant to the obtaining of an already true consequent are themselves true. Moreover, this semantic insight allows us to provide compelling counterexamples to Hypothetical Syllogism that are resistant to the usual contextualist response. (shrink)

The hypothetical syllogism is invalid in standard interpretations of conditional sentences. Many arguments of this sort are quite compelling, though, and you can wonder what makes them so. I shall argue that it is our parsimony in regard to connections among events and states of affairs. All manner of things just might, for all we know, be bound up with one another in all sorts of ways. But ordinarily it is better, being simpler, to assume they are unconnected. In so (...) doing, we jump to the conclusions of some compelling but invalid arguments. (shrink)

In this article, I present a schema for generating counterexamples to the argument form known as Hypothetical Syllogism with indicative conditionals. If my schema for generating counterexamples to HS works as I think it does, then HS is invalid for indicative conditionals.

This paper is about two controversial inference-patterns involving counterfactual or subjunctive conditionals. Given a plausible assumption about the truth-conditions of counterfactuals, it is shown that one can't go wrong in applying hypothetical syllogism (i.e., transitivity) so long as the set of worlds relevant for the conclusion is a subset of the sets of worlds relevant for the premises. It is also shown that one can't go wrong in applying antecedent strengthening so long as the set of worlds relevant for the (...) conclusion is a subset of that for the premise. These results are then adapted to Lewis's theory of counterfactuals. (shrink)

It is argued that the so‐called principles of “strong centering” and “weak centering” central to the traditional Lewis‐Stalnaker semantics for counterfactuals are both fallacious. A foundation for an alternative semantics without these prinsciples is outlined. The core idea is that the statistically normal worlds – rather than those worlds most qualitatively similar to the actual world – should serve as the semantical fulcrum.

It has been suggested that intuitions supporting the nonvacuity of counterpossibles can be explained by distinguishing an epistemic and a metaphysical reading of counterfactuals. Such an explanation must answer why we tend to neglect the distinction of the two readings. By way of an answer, I offer a generalized pattern for explaining nonvacuity intuitions by a stand-and-fall relationship to certain indicative conditionals. Then, I present reasons for doubting the proposal: nonvacuists can use the epistemic reading to turn the table against (...) vacuists, telling apart significant from spurious intuitions. Moreover, our intuitions tend to survive even if we clear-headedly intend a metaphysical reading. -/- . (shrink)

The material account of indicative conditionals faces a legion of counterexamples that are the bread and butter in any entry about the subject. For this reason, the material account is widely unpopular among conditional experts. I will argue that this consensus was not built on solid foundations, since these counterexamples are contextual fallacies. They ignore a basic tenet of semantics according to which when evaluating arguments for validity we need to maintain the context constant, otherwise any argumentative form can be (...) rendered invalid. If we maintain the context fixed, the counterexamples to the material account are disarmed. Throughout the paper I also consider the ramifications of this defence, make suggestions to prevent contextual fallacies, and anticipate some possible misunderstandings and objections. (shrink)

I argue that to know that a proposition is true one must have justification for being certain that the proposition is true. That is, one must have infallible epistemic justification for believing the proposition. It is widely accepted among epistemologists that we rarely, if ever, have such strong justification for our beliefs. It follows that there is precious little that we know. That conclusion is unacceptable to many philosophers. I argue that the positions that lead to the skeptical conclusion are (...) well-motivated and that the skeptical conclusion is implicitly accepted by ordinary speakers. My dissertation has three main components: a metaphilosophical position, an epistemological position, and an error theory. First, the metaphilosophical position. One very important part of philosophy is the analysis of our ordinary concepts. Analysis of our concepts begins with reflecting on what we are inclined to say about various actual and possible cases when considered under specific descriptions. This traditional method has recently come under attack, due in part to the rise of semantic externalism. I agree with externalists that if ‘meaning is reference’ then there is little reason to think reflecting on our concepts from the armchair will provide insight to the nature of the concepts we investigate. I defend a version of semantic internalism which grounds meaning in factors with which subjects are directly acquainted. That view supports the traditional methodology. Furthermore, as the goal of philosophical analysis is to accurately describe concepts of philosophical interest, the only kind of objection that could be decisive against a proposed analysis is that it does not correctly describe our concept. That opens the door to a skeptical analysis of knowledge. Second, the epistemological position. I argue that the unacceptability of sentences of the form “S knows that p but it is possible for S that not-p” is best explained by the hypothesis that our concept of knowledge requires having justification for being certain that what one believes is true. I offer as a criterion of justified certainty the idea that when one knows a proposition is true, one is in a position to decisively answer questions about one’s knowledge of that proposition. I survey a number of competing theories of knowledge and show that they allow for the possibility of knowledge when one fails my criterion of decisive answerability. Those views fail my criterion because according to those views there is nothing the subject is aware of that guarantees for the subject that the allegedly known proposition is true. On that basis, I contend that knowledge is direct awareness of the factors that constitute the truth of the proposition one believes. Third, the error theory. Of course, we rarely have direct awareness of the factors that constitute the truth of the propositions we believe. So, our knowledge attributions are generally false. Yet, they are overwhelmingly natural to make. I argue that competent speakers are often quick to recognize knowledge attributions as a kind of ‘loose talk’ akin to the way we loosely ascribe geometric properties to ordinary objects. We regularly call objects ‘square’ that are not even close to being square, and we are quick to recognize this when challenged. I argue that we do this because we are so accustomed to communicating using strict language to make false claims that we often do not attend to the literal falsity of what we are saying. While we accept very demanding standards for knowledge, the phenomenon of recognizing that our knowledge claims are regularly false is as pervasive as our use of loose speech. (shrink)