Principal Principle Research Articles

Beyond the Magical Thinking Behind the Principal Principle

AbstractDavid Lewis'sPrincipal Principle(PP) states that our credence in a single case follows from the general probability of all such cases. Against this stands the Challenge Argument (CA) – to show that the inference is justified. Recent (1) law-to-chance, (2) Bayesian, and (3) propensity theories of probability take up the challenge – but, I argue, fall short. Rather, we should understand (4) propensity via Aristotle's analysis of spontaneity (5) and probabilistic reasoning via theAnti-PPand (6) the practice ofbundling one offs, where (7)forced bad-odds one offsilluminate how extensive a role luck plays in our lives.

Re-thinking local causality

There is widespread belief in a tension between quantum theory and special relativity, motivated by the idea that quantum theory violates J. S. Bell’s criterion of local causality, which is meant to implement the causal structure of relativistic space-time. This paper argues that if one takes the essential intuitive idea behind local causality to be that probabilities in a locally causal theory depend only on what occurs in the backward light cone and if one regards objective probability as what imposes constraints on rational credence along the lines of David Lewis’ Principal Principle, then one arrives at the view that whether or not Bell’s criterion holds is irrelevant for whether or not local causality holds. The assumptions on which this argument rests are highlighted, and those that may seem controversial are motivated.

New foundations for counterfactuals

Philosophers typically rely on intuitions when providing a semantics for counterfactual conditionals. However, intuitions regarding counterfactual conditionals are notoriously shaky. The aim of this paper is to provide a principled account of the semantics of counterfactual conditionals. This principled account is provided by what I dub the Royal Rule, a deterministic analogue of the Principal Principle relating chance and credence. The Royal Rule says that an ideal doxastic agent’s initial grade of disbelief in a proposition $$A$$ , given that the counterfactual distance in a given context to the closest $$A$$ -worlds equals $$n$$ , and no further information that is not admissible in this context, should equal $$n$$ . Under the two assumptions that the presuppositions of a given context are admissible in this context, and that the theory of deterministic alethic or metaphysical modality is admissible in any context, it follows that the counterfactual distance distribution in a given context has the structure of a ranking function. The basic conditional logic V is shown to be sound and complete with respect to the resulting rank-theoretic semantics of counterfactuals.

In Defense of IP: A Response to Pettigrew

Back in 2008 I argued that Lewis misstated his own Principal Principle when he formalized it. His verbal statement said simply that if one knows what the chance of e is then one should (barring magical information from the future) adopt it as one’s credence. There was nothing in that statement about conditionalization on the truth of ur-chance functions. And I pointed out that ur-chance functions of the kind one finds in physics do not come with assignments of probability to propositions asserting the truth of ur-chance functions. Nor does anything in their epistemic use require that they be extended to deliver such assignments. Then I introduced IP as a natural generalization of PP that said that if you don’t know what the correct ur-chance function is, you obtain your credences from a weighted mixture of the chances assigned by epistemically possible ur-chance functions.2 My response to Pettigrew’s criticism of my proposal can be quick, since he has acknowledged that the problems that he adduces for IP don’t arise unless ur-chance functions are extended to assign probabilities to propositions of the form [Cch]. I will give a brief defense of the epistemology implicit in IP, motivate the restriction against extending ur-chance functions, and point out a mistake in his argument that a reductionist about chance must reject the restriction. First a bit of terminology:

What Chance‐Credence Norms Should Not Be

AbstractA chance‐credence norm states how an agent's credences in propositions concerning objective chances ought to relate to her credences in other propositions. The most famous such norm is the Principal Principle (PP), due to David Lewis. However, Lewis noticed that PP is too strong when combined with many accounts of chance that attempt to reduce chance facts to non‐modal facts. Those who defend such accounts of chance have offered two alternative chance‐credence norms: the first is Hall's and Thau's New Principle (NP); the second is Ismael's General Recipe (IP). Thus, the question arises: Should we adopt NP or IP or both? In this paper, I argue that IP has unacceptable consequences when coupled with reductionism, so we must accept NP alone.

Jeffrey Conditionalization, the Principal Principle, the Desire as Belief Thesis, and Adams’s Thesis

I show that David Lewis’s principal principle is not preserved under Jeffrey conditionalization. Using this observation, I argue that Lewis’s reason for rejecting the desire as belief thesis and Adams’s thesis applies also to his own principal principle. 1 Introduction2 Adams’s Thesis, the Desire as Belief Thesis, and the Principal Principle3 Jeffrey Conditionalization4 The Principal Principles Not Preserved under Jeffrey Conditionalization5 Inadmissible Experiences

A NEW EPISTEMIC UTILITY ARGUMENT FOR THE PRINCIPAL PRINCIPLE

AbstractJim Joyce has presented an argument for Probabilism based on considerations of epistemic utility. In a recent paper, I adapted this argument to give an argument for Probablism and the Principal Principle based on similar considerations. Joyce's argument assumes that a credence in a true proposition is better the closer it is to maximal credence, whilst a credence in a false proposition is better the closer it is to minimal credence. By contrast, my argument in that paper assumed (roughly) that a credence in a proposition is better the closer it is to the objective chance of that proposition. In this paper, I present an epistemic utility argument for Probabilism and the Principal Principle that retains Joyce's assumption rather than the alternative I endorsed in the earlier paper. I argue that this results in a superior argument for these norms.

Study on the Evaluation Method for Energy Saving and Emission Reduction Effect of Power Plant

Thermal power as a focus area for energy saving and pollution reduction, energy saving and environmental protection work is particularly important.This article mainly introduced principal components analytic method basic philosophy and principle, principal components analysis geometry significance, sample principal components deriving, overall principal components and nature, and using this method to known five power plant unit's actual movement when the pollutant emissions and the water used have carried on the quality synthetic evaluation. And gives the appraisal and the basic improvement opinion based on the analysis result to various power plants.The results showed that: The method eliminates the influence of subjective factors on the evaluation, obtain a comprehensive evaluation index which can be evaluated quantitatively.

The Principal Principle

AbstractI analyze optimal loan modification schemes in a stochastic home price and stochastic interest-rate environment. Lenders maximize loan values by managing the borrower’s option to default on the loan and prepayment option. Given negative equity, controlling for the borrower’s ability to pay, rate reductions and maturity extensions result in a higher probability of redefault by homeowners even after modification of their loans. In contrast, loan write-downs (the Principal Principle), not a favored recipe, are value maximizing for the lender. A shared-appreciation mortgage enhances the ability to pay, mitigates adverse selection, and reduces the present value of expected deadweight foreclosure costs.

Causation, Chance, and the Rational Significance of Supernatural Evidence

In “A Subjectivist’s Guide to Objective Chance,” David Lewis says that he is “led to wonder whether anyone but a subjectivist is in a position to understand objective chance.” The present essay aims to motivate this same Lewisean attitude, and a similar degree of modest subjectivism, with respect to objective causation. The essay begins with Newcomb problems, which turn on an apparent tension between two principles of choice: roughly, a principle sensitive to the causal features of the relevant situation, and a principle sensitive only to evidential factors. Two-boxers give priority to causal beliefs, and one-boxers to evidential beliefs. The essay notes that a similar issue can arise when the modality in question is chance, rather than causation. In this case, the conflict is between decision rules based on credences guided solely by chances, and rules based on credences guided by other sorts of probabilistic evidence. Far from excluding cases of the latter kind, Lewis’s Principal Principle explicitly allows for them, in the form of the caveat that credences should follow beliefs about chances only in the absence of “inadmissible evidence.” The essay then exhibits a tension in Lewis’s views on these two matters, by presenting a class of decision problems—some of them themselves Newcomb problems—in which Lewis’s view of the relevance of inadmissible evidence seems in tension with his causal decision theory. It offers a diagnosis for this dilemma and proposes a remedy, based on an extension of a proposal due to Ned Hall and others from the case of chance to that of causation. The remedy suggests a new view of the relation between causal decision theory and evidential decision theory, namely, that they stand to each other much as chance stands to credence, being objective and subjective faces of the same practical coin. This has much the same metaphysical benefits as Lewis’s own view of chance and also throws interesting new light on Newcomb problems, providing an irenic resolution of the apparent disagreement between causal and evidential decision rules.

An ‘Evidentialist’ Worry About Joyce's Argument for Probabilism

Joyce (1998) argues that for any credence function that doesn't satisfy the probability axioms, there is another function that dominates it in terms of accuracy. But if some potential credence functions are ruled out as violations of the Principal Principle, then some non-probabilistic credence functions fail to be dominated. We argue that to fix Joyce's argument, one must show that all epistemic values for credence functions derive from accuracy. 1. Some background on arguments for probabilism Probabilism asserts that every epistemically rational agent S's 'degrees of confi- dence' (a.k.a., 'degrees of credence' or 'credences') should be faithfully repre- sentable via some probability function b from the set of propositions in S's doxastic space to the real numbers. All of the arguments for probabilism that one finds in the literature are of the following (rough-and-ready) general form:

Accuracy, Chance, and the Principal Principle

In “A Nonpragmatic Vindication of Probabilism,” James M. Joyce attempts to “depragmatize” de Finetti’s prevision argument for the claim that our credences ought to satisfy the axioms of the probability calculus. This article adapts Joyce’s argument to give nonpragmatic vindications of David Lewis’s original Principal Principle as well as recent reformulations due to Ned Hall and Jenann Ismael. Joyce enumerates properties that a function must have if it is to measure the distance from a set of credences to a set of truth values; he shows that, on any such measure, and for any set of credences that violates the probability axioms, there is a set that satisfies those axioms that is closer to every possible set of truth values. This article replaces truth values with objective chances in this argument; it shows that for any set of credences that violates the probability axioms or the Principal Principle, there is a set that satisfies both that is closer to every possible set of objective chances and similarly for Ned Hall’s New Principle and Jenann Ismael’s Generalized Principal Principle. Along the way, the article provides new arguments for some of Joyce’s central conditions on distance measures, and it answers two pressing objections to Joyce’s strategy.

Chance without Credence

It is a standard view that the concept of chance is inextricably related to the technical concept of credence. One influential version of this view is that the chance role is specified by (something in the neighborhood of) David Lewis's Principal Principle, which asserts a certain definite relation between chance and credence. If this view is right, then one cannot coherently affirm that there are chance processes in the physical world while rejecting the theoretical framework in which credence is defined, namely the Bayesian framework. This is surprising; why should adopting a theory that says there are chances at work in nature put any particular constraints on our theorizing about epistemology and rational choice? It is quite plausible that in order for anything to count as the referent of our concept chance, it would have to be related to epistemic rationality in a certain way—roughly, it is rational to have more confidence that something will happen the greater you think its chance is. But this commonsensical idea does not seem to be inherently committed to any particular theoretical approach to rationality, so why should we think that adopting the Bayesian approach is a prerequisite for thinking coherently about chance? I propose and defend a replacement for the Principal Principle which makes no use of the concept of credence. I also argue that this replacement is advantageous for the project of theorizing about the nature of chance. 1 The Entanglement of Chance with Credence2 Desiderata for a Replacement for PP3 Disentangling Chance from Credence4 What RP Demands of a Bayesian Subject5 How Narrowly RP Constrains the Chance Function6 An Objection7 An Unexpected Benefit8 ConclusionAppendix A: Any Subject with Credences who Obeys PP also Obeys RPAppendix B: Any Subject with Credences who Obeys RP also Approximately Obeys PP

The Principal Principle and Theories of Chance: Another Bug?

Objective chance, or the “big bad bug” of David Lewis's account of Humean Supervenience forces, as is well known, is a modification of the Principal Principle. Here, I argue that standard assumptions regarding conditional probabilities entail several puzzling consequences for Lewis's New Principle, namely, an apparent requirement to account for the chance of a theory of chance. These problems, I argue, cannot be adequately answered within the received framework, and so I suggest that an interpretation of conditional probabilities in terms of Alan Hájek's recent work might go some distance toward their resolution.

The Principal Principle: Optimal Modification of Distressed Home Loans

Lenders will often restructure a loan rather than foreclose on a property because it is less value-destroying. A loan modification primarily entails a change in the loan rate, principal balance and/or remaining time to maturity. We analyze optimal loan modification schemes in a stochastic home price and stochastic interest-rate environment. Lenders maximize their loan values by managing the value of the borrower's option to default on the loan and prepayment option. We argue that, controlling for the borrower's ability to pay, loan modifications via rate reductions and maturity extensions are ineffective, leading to dissipation in loan value to the lender, and resulting in a high probability of re-default by homeowners even after modification of their loans. In contrast, loan write-downs (the Principal Principle), not a favored recipe, and sometimes prohibited by covenants, are value-maximizing for the lender. A useful structuring device, the shared appreciation mortgage, enhances the ability to pay, mitigates adverse selection, and reduces the present value of expected deadweight foreclosure costs.

Constraining prior probabilities of phylogenetic trees

Although Bayesian methods are widely used in phylogenetic systematics today, the foundations of this methodology are still debated among both biologists and philosophers. The Bayesian approach to phylogenetic inference requires the assignment of prior probabilities to phylogenetic trees. As in other applications of Bayesian epistemology, the question of whether there is an objective way to assign these prior probabilities is a contested issue. This paper discusses the strategy of constraining the prior probabilities of phylogenetic trees by means of the Principal Principle. In particular, I discuss a proposal due to Velasco (Biol Philos 23:455–473, 2008) of assigning prior probabilities to tree topologies based on the Yule process. By invoking the Principal Principle I argue that prior probabilities of tree topologies should rather be assigned a weighted mixture of probability distributions based on Pinelis’ (P Roy Soc Lond B Bio 270:1425–1431, 2003) multi-rate branching process including both the Yule distribution and the uniform distribution. However, I argue that this solves the problem of the priors of phylogenetic trees only in a weak form.

CHANCE AND ACTUALITY

The relation between chance and actuality gives rise to a puzzle. On the one hand, it may be a chancy matter what will actually happen. On the other hand, the standard semantics for ‘actually’ implies that sentences beginning with ‘actually’ are never contingent. To elucidate the puzzle, I defend a kind of objective semantic indeterminacy: in a chancy world, it may be a chancy matter which proposition is expressed by sentences containing ‘actually’. I bring this thesis to bear on certain counter-examples, proposed by Hawthorne and Lasonen-Aarnio, to Lewis' ‘principal principle’.

Two Mistakes Regarding the Principal Principle

This paper examines two mistakes regarding David Lewis’ Principal Principle that have appeared in the recent literature. These particular mistakes are worth looking at for several reasons: The thoughts that lead to these mistakes are natural ones, the principles that result from these mistakes are untenable, and these mistakes have led to significant misconceptions regarding the role of admissibility and time. After correcting these mistakes, the paper discusses the correct roles of time and admissibility. With these results in hand, the paper concludes by showing that one way of formulating the chance–credence relation has a distinct advantage over its rivals. 1. Introduction2. Background 2.1. The chance function2.2. The chance–credence relation2.3. Assumptions3. Assessing the First Mistake 3.1. The first mistake3.2. Motivating the first mistake3.3. Why the first mistake is problematic3.4. Consequences of the first mistake4. The Role of Admissibility 4.1. Crystal balls4.2. Usefulness4.3. The strength of PP14.4. Lewis and admissibility5. Assessing the Second Mistake 5.1. The second mistake5.2. Motivating the second mistake5.3. Why the second mistake is problematic5.4. The role of time6. Assessing the Chance–Credence Relation 6.1. Take I: Lewis' grounding argument6.2. Take II: general grounding arguments6.3. The winner

Second Guessing: A Self-Help Manual

ABSTRACTI develop a general framework with a rationality constraint that shows how coherently to represent and deal with second-order information about one's own judgmental reliability. It is a rejection of and generalization away from the typical Bayesian requirements of unconditional judgmental self-respect and perfect knowledge of one's own beliefs, and is defended by appeal to the Principal Principle. This yields consequences about maintaining unity of the self, about symmetries and asymmetries between the first- and third-person, and a principled way of knowing when to stop second-guessing oneself. Peer disagreement is treated as a special case where one doubts oneself because of news that an intellectual equal disagrees. This framework, and variants of it, imply that the typically stated belief that an equally reliably peer disagrees is incoherent, and thus that pure rationality constraints without further substantive information cannot give an answer as to what to do. The framework also shows that treating both ourselves and others as thermometers in the disagreement situation does not imply the Equal Weight view.

A Critique of Integrity: Has a Commander a Moral Obligation to Uphold his Own Principles?

Integrity is generally considered to be an important military virtue. The first part of this article tries to make sense of integrity's many, often contradicting, meanings. Both in the military and elsewhere, its most common understanding seems to be that integrity requires us to live according to one's personal principal values and principles – we have a moral obligation to do so, and it is a prerequisite to be able to ‘look ourselves in the mirror.’ This notion of integrity as upholding personal values and principles is a very problematic one in itself, especially to those working in the military. For several reasons, perhaps the role that the virtue of integrity has in a military organization could in fact be better played by other virtues.