A Boltzmann brain is a randomly‐formed configuration of matter that is conscious. According to some theories that cosmologists take seriously, the universe is so spatiotemporally large that it contains a great many Boltzmann brains that are duplicates of you. In the light of this it seems to follow that you should have significant confidence that you are a Boltzmann brain. What's worse, your situation seems to be “cognitively unstable”: It seems unstable to end up confident that you are a Boltzmann brain because you should then think that your apparent cosmological evidence was randomly generated and hence that your confidence was unwarranted. But it also seems unstable to end up confident that you are not a Boltzmann brain because then you should follow your cosmological evidence to the conclusion that many Boltzmann brain duplicates of you exist, and hence that you are probably a Boltzmann brain. A case involving unreliable vision exhibits a similar threat of instability. A simple Bayesian model of that case, however, shows that the threat is an illusion. And a corresponding model suggests that the same goes for the threat of instability associated with Boltzmann brains.

Allocating resources to maximize the probability that humanity survives a set of existential risks has a different structure from many decision problems, as the objective is the product of the probabilities of desired outcomes rather than the sum. We derive the optimal solution to this problem and use this solution to evaluate the choices that people make when presented with decisions that have this multiplicative structure. Our participants (total N=2,072) are appropriately sensitive to how responsive a risk is to investment, but are conservative in their decisions and do not allocate enough resources to risks with lower probability of survival. This pattern persists even with alternative framings that emphasize survival probabilities. Our results highlight a systematic flaw in people's intuitions about how to respond to existential risks, and suggest that people may have particular difficulty with decisions that involve multiplicative objectives.

There are 1,000 of us and one victim. We each increase the level at which a 'discomfort machine' operates on the victim - leading to great discomfort. Suppose that consecutive levels of the machine are so similar that the victim cannot distinguish them. Have we acted permissibly? According to the 'no-difference argument' the answer is 'yes' because each of our actions was guaranteed to make the victim no worse off. This argument is of interest because, if it is sound, similar arguments threaten intuitive moral verdicts about many cases in which a large number of individual choices cumulatively make a great difference, while each choice seems to make no difference on its own. But the argument is not sound, as is shown by a simple objection based on a plausible dominance principle - an objection that avoids challenges that have been brought against previous criticisms of the no-difference argument.

(1) Suppose that you care only about speaking the truth, and are confident that some particular deterministic theory is true. If someone asks you whether that theory is true, are you rationally required to answer 'yes'? (2) Suppose that you face a problem in which (as in Newcomb's problem) one of your options - call it 'taking two boxes' - causally dominates your only other option. Are you rationally required to take two boxes? Those of us attracted to causal decision theory are under pressure to answer 'yes' to both questions. However, it has been shown that many existing decision theories are inconsistent with doing so (Ahmed 2014). A simple proof shows that the same goes for an even wider class of theories: all 'suppositional' decision theories. The moral is that causal decision theorists must either answer 'no' to one of the above questions, or else abandon suppositional decision theories.

It would be good to have a Bayesian decision theory that assesses our decisions and thinking according to everyday standards of rationality-standards that do not require logical omniscience (Garber, 1983; Hacking, 1967). To that end we develop a "fragmented" decision theory in which a single state of mind is represented by a family of credence functions, each associated with a distinct choice condition (Lewis, 1982; Stalnaker, 1984). The theory imposes a local coherence assumption guaranteeing that as an agent's attention shifts, successive batches of "obvious" logical information become available to her. A rule of expected utility maximization can then be applied to the decision of what to attend to next during a train of thought. On the resulting theory, rationality requires ordinary agents to be logically competent and to often engage in trains of thought that increase the unification of their states of mind. But rationality does not require ordinary agents to be logically omniscient.

Is there an English word that ends in ‘MT’? (If you are stumped, think about it for a moment and then read the last word of this abstract.) Before you figured out (or read) the answer to that question, did you possess the information that the word that is the answer is an English word that ends in ‘MT’? In a sense, yes: the word was in your vocabulary. But in another sense, no: perhaps you weren’t able to immediately answer the puzzle question. For finite agents, this phenomenon is unavoidable. We often possess a piece of information for some purposes (or with respect to some elicitation conditions) but not for other purposes (or conditions). This suggests that a mental state be represented not by a single batch of information, but rather by an ‘access table’—a function from purposes to batches of information. This representation makes clear what happens during certain ‘aha!’ moments in reasoning. It also allows us to model agents who exhibit imperfect recall, confusion, and mental fragmentation. And it sheds light on the difference between propositional knowledge and knowledge-how. The upshot is that representing mental states using access tables is more fruitful than one might have dreamt.

Counter-intuitive consequences of both causal decision theory and evidential decision theory are dramatized. Each of those theories is thereby put under some pressure to supply an error theory to explain away intuitions that seem to favour the other. Because trouble is stirred up for both sides, complacency about Newcomb’s problem is discouraged.

One way to reduce waste and to make a system more robust is to allow its components to pool resources. For example, banks might insure each other or share a common capital reserve. Systems whose resources have been pooled in this way are highly prevalent in such diverse domains as finance, infrastructure, health care, emergency response, and engineering. However, these systems have a combination of characteristics that leave them vulnerable to poor decision making: non-linearity of risk, obvious rewards combined with hidden costs, and political and market incentives that encourage inadequate safety margins. Three studies demonstrate a tendency for managers of such systems to underestimate the probability of cascading failures. We describe a series of behaviorally based policy interventions to mitigate the resulting hazards.

Poza niepewnością co do tego, jaki jest świat, mozna byc takze niepewnym swojego przestrzennego lub czasowgo polozenia w świecie. Celem artykulu jest postawienie problemu wynikającego z polączenia tych dwoch rodzajow niepewności, a nastepnie rozwiązanie go i wyciągniecie dwoch lekcji z tego rozwiązania. Oryginal: „Self-Locating Belief and the Sleeping Beauty Problem”, Analysis 60 (2000), issue 2: 143–147. DOI: https://doi.org/10.1093/analys/60.2.143. Przeklad za zgodą Autora. Informacje o Tlumaczu: Mgr Krzysztof Nowicki — doktorant na Wydziale Filozofii Katolickiego Uniwersytetu Lubelskiego Jana Pawla II; adres do korespondencji — e-mail: nowicki.krz@gmail.com

The ability to analyze arguments is critical for higher-level reasoning, yet previous research suggests that standard university education provides only modest improvements in students’ analytical-reasoning abilities. What pedagogical approaches are most effective for cultivating these skills? We investigated the effectiveness of a 12-week undergraduate seminar in which students practiced a software-based technique for visualizing the logical structures implicit in argumentative texts. Seminar students met weekly to analyze excerpts from contemporary analytic philosophy papers, completed argument visualization problem sets, and received individualized feedback on a weekly basis. We found that seminar students improved substantially more on LSAT Logical Reasoning test forms than did control students ( d = 0.71, 95% CI: [0.37, 1.04], p < 0.001), suggesting that learning how to visualize arguments in the seminar led to large generalized improvements in students’ analytical-reasoning skills. Moreover, blind scoring of final essays from seminar students and control students, drawn from a parallel lecture course, revealed large differences in favor of seminar students ( d = 0.87, 95% CI: [0.26, 1.48], p = 0.005). Seminar students understood the arguments better, and their essays were more accurate and effectively structured. Taken together, these findings deepen our understanding of how visualizations support logical reasoning and provide a model for improving analytical-reasoning pedagogy.

Moriarty has posed a difficult logic problem, and has arranged for a bomb to explode unless Watson types in the correct answer by noon. Watson has never thought about that problem before, and even experienced logicians take hours to solve it. It is seconds away from noon. However, Moriarity was absent-minded enough to leave the answer to the problem on a Post-It note attached to the back of the bomb. Watson is informed of all of the above, but hasn’t yet looked at the note. His options are to look at the note (which would put him in a position to type in what it says), or, alternatively, to enter an answer of his choice into the bomb’s keypad without looking at the note. Is it rationally permissible for Watson to look at the note? The answer is elementary: it is rationally permissible. Standard decision theory delivers the opposite answer. It entails that it would be irrational for Watson to look at the note. One way to see this is to note that standard decision theory assumes that the belief state of a rational agent is represented by a single probability function satisfying restrictive coherence axioms. As they are normally interpreted, those axioms entail that a rational agent is logically omniscient: that she assigns probability 1 to every logical truth, and assigns each consequence of a claim at least as much probability as she assigns the claim itself.

Say that an agent is epistemically humble if she is less than fully confident that her opinions will converge to the truth, given appropriate evidence. Is such humility rationally permissible? According to Gordon Belot’s orgulity argument: the answer is yes, but long-run convergence-to-the-truth theorems force Bayesians to answer no. That argument has no force against Bayesians who reject countable additivity as a requirement of rationality. Such Bayesians are free to count even extreme humility as rationally permissible. Furthermore, dropping countable additivity does not render Bayesianism more vulnerable to the charge that it is excessively subjective.

The "puzzle of the unmarked clock" derives from a conflict between the following: (1) a plausible principle of epistemic modesty, and (2) "Rational Reflection", a principle saying how one's beliefs about what it is rational to believe constrain the rest of one's beliefs. An independently motivated improvement to Rational Reflection preserves its spirit while resolving the conflict.

When one encounters disagreement about the truth of a factual claim from a trusted advisor who has access to all of one's evidence, should that move one in the direction of the advisor's view? Conciliatory views on disagreement say "yes, at least a little." Such views are extremely natural, but they can give incoherent advice when the issue under dispute is disagreement itself. So conciliatory views stand refuted. But despite first appearances, this makes no trouble for *partly* conciliatory views: views that recommend giving ground in the face of disagreement about many matters, but not about disagreement itself.

Many have claimed that unspecific evidence sometimes demands un- sharp, indeterminate, imprecise, vague, or interval-valued probabili- ties. Against this, a variant of the diachronic Dutch Book argument shows that perfectly rational agents always have perfectly sharp prob- abilities.

Abstract There is a huge chasm between the sort of lawful determination that figures in fundamental physics, and the sort of causal detennination that figures in the ‘folk physics’ of everyday objects. For example, consider a rock sitting on a desk. In everyday life, we think of the rock as having a fixed stock of dispositions—the disposition to slide on the desk when pushed, to shatter when struck by a sledgehammer, and so on. When a strong interaction comes the rock’s way, the rock’s dispositions detennine how it will respond. More generally, we think of the behavior of an ordinary object as being determined by a small set of conditions.

How should you take into account the opinions of an advisor? When you rr completely defer to the advisor's judgment (the manner in which she responds to her evidence), then you should treat the advisor as a guru. Roughly, that means you should believe what you expect she would believe, if supplied with your extra evidence. When the advisor is your own future self, the resulting principle amounts to a version of the Reflection Principle-a version amended to handle cases of information loss. When you count an advisor as an epistemic peer, you should give her conclusions the same weight as your own. Denying that view-call it the "equal weight view"-leads to absurdity: the absurdity that you could reasonably come to believe yourself to be an epistemic superior to an advisor simply by noting cases of disagreement with her, and taking it that she made most of the mistakes. Accepting the view seems to lead to another absurdity: that one should suspend judgment about everything that one's smart and well-informed friends disagree on, which means suspending judgment about almost everything interesting. But despite appearances, the equal weight view does not have this absurd consequence. Furthermore, the view can be generalized to handle cases involving not just epistemic peers, but also epistemic superiors and inferiors.

When it comes to evaluating our own abilities and prospects, most (non-depressed) people are subject to a distorting bias. We think that we are better – friendlier, more well-liked, better leaders, and better drivers – than we really are. Once we learn about this bias, we should ratchet down our self-evaluations to correct for it. But we don’t. That leaves us with an uncomfortable tension in our beliefs: we knowingly allow our beliefs to differ from the ones that we think are supported by our evidence. We can mitigate the tension by waffling between two belief states: a reflective state that has been recalibrated to take into account our tendency to overrate ourselves, and a non-reflective state that has not.