The Definability of the set of natural numbers in the 1925 Principia Mathematica

In his new introduction to the 1925 second edition of Principia Mathematica, Russell maintained that by adopting Wittgenstein's idea that a logically perfect language should be extensional mathematical induction could be rectified for finite cardinals without the axiom of reducibility. In an Appendix B, Russell set forth a proof. Gödel caught a defect in the proof at *89.16, so that the matter of rectification remained open. Myhill later arrived at a negative result: Principia with extensionality principles and without reducibility cannot recover mathematical induction. The finite cardinals are indefinable in it. This paper shows that while Gödel and Myhill are correct, Russell was not wrong. The 1925 system employs a different grammar than the original Principia. A new proof for *89.16 is given and induction is recovered.     

Expressivity results for deontic logics of collective agency

We use a deontic logic of collective agency to study reducibility questions about collective agency and collective obligations. The logic that is at the basis of our study is a multi-modal logic in the tradition of stit (‘sees to it that’) logics of agency. Our full formal language has constants for collective and individual deontic admissibility, modalities for collective and individual agency, and modalities for collective and individual obligations. We classify its twenty-seven sublanguages in terms of their expressive power. This classification enables us to investigate reducibility relations between collective deontic admissibility, collective agency, and collective obligations, on the one hand, and individual deontic admissibility, individual agency, and individual obligations, on the other.

     

Amending Frege’s <Emphasis Type="Italic">Grundgesetze der Arithmetik</Emphasis>

Frege’s Grundgesetze der Arithmetik is formally inconsistent. This system is, except for minor differences, second-order logic together with an abstraction operator governed by Frege’s Axiom V. A few years ago, Richard Heck showed that the ramified predicative second-order fragment of the Grundgesetze is consistent. In this paper, we show that the above fragment augmented with the axiom of reducibility for concepts true of only finitely many individuals is still consistent, and that elementary Peano arithmetic (and more) is interpretable in this extended system.     

Computably Enumerable Equivalence Relations

We study computably enumerable equivalence relations (ceers) on N and unravel a rich structural theory for a strong notion of reducibility among ceers.     

Leon Chwistek,The Principles of the Pure Type Theory (1922), translated by Adam Trybus with an Introductory Note by Bernard Linsky

‘The Principles of the Pure Type Theory’ is a translation of Leon Chwistek's 1922 paper ‘Zasady czystej teorii typów’. It summarizes Chwistek's results from a series of studies of the logic of Whitehead and Russell's Principia Mathematica which were published between 1912 and 1924. Chwistek's main argument involves a criticism of the axiom of reducibility. Moreover, ‘The Principles of the Pure Type Theory’ is a source for Chwistek's views on an issue in Whitehead and Russell's ‘no-class theory of classes’ involving the notion of ‘scope’.     

Belief,Credence, and the Preface Paradox

Many discussions of the ‘preface paradox’ assume that it is more troubling for deductive closure constraints on rational belief if outright belief is reducible to credence. I show that this is an error: we can generate the problem without assuming such reducibility. All that we need are some very weak normative assumptions about rational relationships between belief and credence. The only view that escapes my way of formulating the problem for the deductive closure constraint is in fact itself a reductive view: namely, the view that outright belief is credence 1. However, I argue that this view is unsustainable. Moreover, my version of the problem turns on no particular theory of evidence or evidential probability, and so cannot be avoided by adopting some revisionary such theory. In sum, deductive closure is in more serious, and more general, trouble than some have thought.     

∑ 0 n -equivalence relations

In this paper we study the reducibility order _m (defined in a natural way) over _n ⁰ -equivalence relations. In particular, for every n> 0 we exhibit _n ⁰ -equivalence relations which are complete with respect to _m and investigate some consequences of this fact (see Introduction).     

Absolute Error Revisited

When target accuracy is defined as the probability that an individual will respond to an accuracy task within a fixed distance around the target, then the composite error measures, E and AE, are shown to be fairly strong indicators of target accuracy in a relative sense. When AE and E are compared, AE is shown to be an even stronger accuracy indicator than E for most reasonable accuracy requirements. This, plus the fact that AE has certain desirable properties in ANOVA procedures, suggests that AE is a good, composite measure of target accuracy and should be analyzed first to determine if target accuracy differences exist. Subsequent analyses of bias and/or variability are then recommended.     

How “rational” is “rationality”?

Abstract

By taking serious a remark once made by Paul Bernays, namely that an account of the nature of rationality should begin with concept-formation, this article sets out to uncover both the restrictive and the expansive boundaries of rationality. In order to do this some implications of the perennial philosophical problem of the “coherence of irreducibles” will be related to the acknowledgement of primitive terms and of their indefinability. Some critical remarks will be articulated in connection with an over-estimation of rationality - concerning the influence of Kant’s view of human understanding as the formal law-giver of nature (the supposedly “rational structure of the world”), and the apparently innocent (subjectivist) habit to refer to experiential entities as ‘objects’. The other side of the coin will be highlighted with reference to those kinds of knowledge transcending the limits of concept-formation - culminating in formulating the four most basic idea-statements philosophy can articulate about the universe. What is found “in-between” these (restrictive) and (expansive) boundaries of rationality will then briefly be placed within the contours of a threefold perspective on the self-insufficiency of logicality - as merely one amongst many more dimensions conditioning human life. Although the meaning of the most basic logical principles - such as the logical principles of identity, non-contradiction and sufficient reason - will surface in our analysis, exploring some of the complex issues in this respect, such as the relationship between thought and language, will not be analysed. The important role of solidarity - as the basis of critique - will be explained and related both to the role of immanent criticism in rational conversation and the importance of acknowledging what is designated as the principle of the excluded antinomy (which in an ontic sense underlies the logical principle of non-contradiction). The last section of our discussion will succinctly illuminate the proper place of the inevitable trust we ought to have in rationality - while implicitly warning against the rationalistic over-estimation of it (its degeneration into a rationalist “faith in reason”). Our intention is to enhance an awareness of the reality that rationality is embedded in and borders on givens which are not open to further “rational” exploration - givens that both condition (in a constitutive sense) and transcend the limits of conceptual knowledge. Some of the distinctions and insights operative in our analysis are explained in Strauss 2000 and 2003. Yet, most of the systematic perspectives found in this analysis of rationality are only developed in this article for the first time. Since a different study is required to discuss related problems and results found within cognitive science, it cannot be discussed within one article.     

Properties and applications of gramian factoring

The Gramian factorizationG of a GramianR is square and symmetric and has no negative characteristic roots. It is shown to be that square factorization that is, in the least-squares sense, most isomorphic toR, most like a scalarK, and most highly traced, and to be the necessary and sufficient relation between the oblique vectors of an oblique transformation and the orthogonal vectors of the least-squares orthogonal counterpart. A slightly modified Gramian factorization is shown to be the factorization that is most isomorphic to a specified diagonalD, and to be the main part of an iterative procedure for obtaining simplimax, a square factor matrix with simple structure maximized in the sense of having the largest sum of squared diagonal loadings. Several published applications of Gramian factoring are cited.     

Akrasia and conflict in the Nicomachean Ethics

In Nicomachean Ethics VII, Aristotle offers an account of akrasia that purports to salvage the kernel of truth in the Socratic paradox that people act against what is best only through ignorance. Despite Aristotle’s apparent confidence in having identified the sense in which Socrates was right about akrasia, we are left puzzling over Aristotle’s own account, and the extent to which he agrees with Socrates. The most fundamental interpretive question concerns the sense in which Aristotle takes the akratic to be ignorant. The received view in the literature has been the intellectualist interpretation, which takes akratic agents to be so ignorant of the wrongness of what they do as to be unaware of it. In recent decades, many scholars have identified serious problems in this interpretation and have moved towards the non-intellectualist reading, the strong version of which takes clearheaded akrasia to be possible. There is, however, a glaring shortage of discussion of the difficulties facing the strong non-intellectualist reading. In this paper, I present what I take to be the most salient reasons for rejecting strong non-intellectualism, and argue that Aristotle’s text supports a moderate non-intellectualism, according to which clearheaded akrasia is impossible.     

An implicit enumeration method for an exact test of weighted kappa

The kappa coefficient is one of the most widely used measures for evaluating the agreement between two raters asked to assign N objects to one of K nominal categories. Weighted versions of kappa enable partial credit to be awarded for near agreement, most notably in the case of ordinal categories. An exact significance test for weighted kappa can be conducted by enumerating all rater agreement tables with the same fixed marginal frequencies as the observed table, and accumulating the probabilities for all tables that produce a weighted kappa index that is greater than or equal to the observed measure. Unfortunately, complete enumeration of all tables is computationally unwieldy for modest values of N and K. We present an implicit enumeration algorithm for conducting an exact test of weighted kappa, which can be applied to tables of non‐trivial size. The algorithm is particularly efficient for ‘good’ to ‘excellent’ values of weighted kappa that typically have very small p‐values. Therefore, our method is beneficial for situations where resampling tests are of limited value because the number of trials needed to estimate the p‐value tends to be large.     

Supervenience,necessary coextension,and reducibility

Conclusion Supervenience in most of its guises entails necessary coextension. Thus theoretical supervenience entails nomically necessary coextension. Kim's result, thus strengthened, has yet to hit home. I suspect that many supervenience enthusiasts would cool at necessary coextension: they didn't mean to be saying anything quite so strong. Furthermore, nomically necessary coextension can be a good reason for property identification, leading to reducibility in principle. This again is more than many supervenience theorists bargained for. They wanted supervenience without reducibility. It is not always available for this mediating role.     

Tropic of Value*

The authors of this paper earlier argued that concrete objects, such as things or persons, may have final value (value for their own sake), which is not reducible to the value of states of affairs that concern the object in question. Our arguments have been challenged. This paper is an attempt to respond to some of these challenges, viz. those that concern the reducibility issue. The discussion presupposes a Brentano‐inspired account of value in terms of fitting responses to value bearers. Attention is given to a yet another type of reduction proposal, according to which the ultimate bearers of final value are abstract particulars (so‐called tropes) rather than abstract states or facts. While the proposal is attractive ((fone entertains the existence of tropes), it confronts serious difficulties. To recognise tropes as potential bearers of final value, along with other objects, is one thing; but to reduce the final value of concrete objects to the final value of tropes is another matter.     

Completion,reduction and analysis: three proof-theoretic processes in aristotle’s prior analytics

Three distinctly different interpretations of Aristotle’s notion of a sullogismos in Prior Analytics can be traced: (1) a valid or invalid premise-conclusion argument (2) a single, logically true conditional proposition and (3) a cogent argumentation or deduction. Remarkably the three interpretations hold similar notions about the logical relationships among the sullogismoi. This is most apparent in their conflating three processes that Aristotle especially distinguishes: completion (A4-6)reduction(A7) and analysis (A45). Interpretive problems result from not sufficiently recognizing Aristotle’s remarkable degree of metalogical sophistication to distinguish logical syntax from semantics and, thus, also from not grasping him to refine the deduction system of his underlying logic. While it is obvious that Aristotle most often uses ‘sullogimos’ to denote a valid argument of a certain kind, we show that at Prior Analytics A4-6, 7, 45 Aristotle specifically treats a sullogismos as an elemental argument pattern having only valid instances and that such a pattern then serves as a rule of deduction in his syllogistic logic. By extracting Aristotle’s understanding of three proof-theoretic processes, this paper provides new insight into what Aristotle thinks reasoning syllogistically is and, moreover, it resolves three problems in the most recent interpretation that takes a sullogismos to be a deduction     

Kierkegaard's accounts of faith: Their relative centrality

This article is an attempt to clarify the concept of apatheia as it appears in the Praktikos of Evagrius of Pontus. The condition (katastasis) of apatheia is central to the Evagrian understanding of the goal of monastic life, and the Praktikos is the treatise in the writings of Evagrius which deals most thoroughly with apatheia. The thesis of the article is that apatheia should be understood in terms of the Platonic distinction between stability and movement, and apatheia, thus, appears to be two different kinds of conditions, namely imperfect apatheia, related to the daily ascetic struggle of the monks against the demons and the thoughts, and perfect apatheia, related to the peaceful condition of undisturbed prayer, in which the mind contemplates the holy Trinity.     

A Nelsonian Response to ‘the Most Embarrassing of All Twelfth-century Arguments’

Alberic of Paris put forward an argument, ‘the most embarrassing of all twelfth-century arguments’ according to Christopher Martin, which shows that the connexive principles contradict some other logical principles that have become deeply entrenched in our most widely accepted logical theories. Building upon some of Everett Nelson’s ideas, we will show that the steps in Alberic of Paris’ argument that should be rejected are precisely the ones that presuppose the validity of schemas that are nowadays taken as some of the most trivial logical truths: (A∧B) →_AB A and (A∧B) →_AB B, i.e. Simplification.     

Modal skepticism and counterfactual knowledge

Timothy Williamson has recently proposed to undermine modal skepticism by appealing to the reducibility of modal to counterfactual logic (Reducibility). Central to Williamson’s strategy is the claim that use of the same non-deductive mode of inference (counterfactual development, or CD) whereby we typically arrive at knowledge of counterfactuals suffices for arriving at knowledge of metaphysical necessity via Reducibility. Granting Reducibility, I ask whether the use of CD plays any essential role in a Reducibility-based reply to two kinds of modal skepticism. I argue that its use is entirely dispensable, and that Reducibility makes available replies to modal skeptics which show certain propositions to be metaphysically necessary by deductive arguments from premises the modal skeptic accepts can be known.     

Faithful representation,physical extensive measurement theory and Archimedean axioms

The formal methods of the representational theory of measurement (RTM) are applied to the extensive scales of physical science, with some modifications of interpretation and of formalism. The interpretative modification is in the direction of theoretical realism rather than the narrow empiricism which is characteristic of RTM. The formal issues concern the formal representational conditions which extensive scales should be assumed to satisfy; I argue in the physical case for conditions related to weak rather than strong extensive measurement, in the sense of Holman 1969 and Colonius 1978. The problem of justifying representational conditions is addressed in more detail than is customary in the RTM literature; this continues the study of the foundations of RTM begun in an earlier paper. The most important formal consequence of the present interpretation of physical extensive scales is that the basic existence and uniqueness properties of scales (representation theorem) may be derived without appeal to an Archimedean axiom; this parallels a conclusion drawn by Narens for representations of qualitative probability. It is concluded that there is no physical basis for postulation of an Archimedean axiom.