The Principle of Summation

The principle of Summation, which is a technically sharpened version of the familiar claim that a whole is a sum of its parts, is presented by Peter van Inwagen as a trivial truth. I argue to the contrary, that it is incompatible with the natural assumption that a whole may gain or lose parts non-instantaneously. For, as I show, the latter assumption implies that something can be determinately a whole without being determinately a sum of parts, and this, in turn, indicates the falsity of Summation. I point out that the tension between Summation and the possibility of non-instantaneous gain or loss of parts compels us to rethink the relations between the concepts of whole and sum, and may have far reaching consequences for the mereology of physical objects.

---

THE NATURE OF HOPE

Both traditional accounts of hope and some of their recent critics analyze hope exclusively in terms of attitudes that a hoper bears towards a hoped-for prospect, such as desire and probability assignment. I argue that all of these accounts misidentify cases of despair as cases of hope, and so misconstrue the nature of hope. I show that a more satisfactory view is arrived at by noticing that in addition to the aforementioned attitudes, hope involves a characteristic attitude towards an external factor, on whose operation the hoper takes the prospect's realization to depend causally.     

The Influence of Children on Their Parents’ Values

Many parents report that their values are influenced by their children. However, few studies provide direct evidence regarding child–parent value transmission. We review this evidence and propose five main processes of child influence: (i) Passive child influences, causing change in parental values by the mere presence or development of children; (ii) Active child influences, due to children directly attempting to influence their parents’ opinions or providing parents with relevant information; (iii) Differentiation, the emergence of a distinction between parents’ own personal values and their socialization values; (iv) Reciprocal influences; in which parents’ and children’ influences are intertwined; and (v) Counter‐influences, in which parental values change in a direction opposite to that of children's values. A study on child influence illustrates some of these processes. The roles of migration, aging, and parent and child characteristics in child‐to‐parent influences are discussed.     

Indiscriminability as Indiscernibility by Default

Most solutions to the sorites reject its major premise, i.e. the quantified conditional . This rejection appears to imply a discrimination between two elements that are supposed to be indiscriminable. Thus, the puzzle of the sorites involves in a fundamental way the notion of indiscriminability. This paper analyzes this relation and formalizes it, in a way that makes the rejection of the major premise more palatable. The intuitive idea is that we consider two elements indiscriminable by default, i.e. unless we know some information that discriminates between them. Specifically, following Rough Set Theory, two elements are defined to be indiscernible if they agree on the vague property in question. Then, a is defined to be indiscriminable from b if a is indiscernible by default from b. That is to say, a is indiscriminable from b if it is consistent to assume that a and b agree on the relevant vague property. Indiscernibility by default is formalized with the use of Default Logic, and is shown to have intuitively desirable properties: it is entailed by equality, is reflexive and symmetric. And while the relation is neither transitive nor substitutive, it is “almost” substitutive. This definition of indiscriminability is incorporated into three major theories of vagueness, namely the supervaluationist, epistemic, and contextualist views. Each one of these theories is reduced to a different strategy dealing with multiple extensions in Default Logic, and the rejection of the major premise is shown to follow naturally. Thus, while the proposed notion of indiscriminability does not solve the sorites by itself, it does make the unintuitive conclusion of many of its proposed solutions—the rejection of the major premise—a bit easier to accept.     

A Measure for the Reliability of a Rating Scale Based on Longitudinal Clinical Trial Data

A new measure for reliability of a rating scale is introduced, based on the classical definition of reliability, as the ratio of the true score variance and the total variance. Clinical trial data can be employed to estimate the reliability of the scale in use, whenever repeated measurements are taken. The reliability is estimated from the covariance parameters obtained from a linear mixed model. The method provides a single number to express the reliability of the scale, but allows for the study of the reliability’s time evolution. The method is illustrated using a case study in schizophrenia. The authors are grateful to J&J PRD for kind permission to use their data. We gratefully acknowledge support from the Belgian IUAP/PAI network “Statistical Techniques and Modeling for Complex Substantive Questions with Complex Data.”     

Prosocial behavior from early to middle childhood: genetic and environmental influences on stability and change

Prosocial behavior is important for the functioning of society. This study investigates the extent to which environment shared by family members, nonshared environment, and genetics account for children's prosocial behavior. The prosocial behavior of twins (9,424 pairs) was rated by their parents at the ages of 2, 3, 4, and 7 and by their teachers at age 7. For parent ratings, shared environmental effects decreased from .47 on average at age 2 to .03 at age 7, and genetic effects increased from .32 on average to .61. The finding of weak shared environmental effects and large heritability at age 7 was largely confirmed through the use of teacher ratings. Using longitudinal genetic analyses, the authors conclude that genetic effects account for both change and continuity in prosocial behavior and nonshared environment contributes mainly to change.     

A "Jekyll and Hyde" within: aggressive versus friendly interactions in REM and non-REM dreams

We hypothesized that representations of social interactions in REM and non-REM (NREM) dreams would reflect differing regional brain activation patterns associated with the two sleep states, and that levels of aggressive interactions would be higher in REM than in NREM dreams. One hundred REM, 100 NREM, and 100 wake reports were collected in the home from 8 men and 7 women using the Nightcap sleep-wake mentation-monitoring system and scored for number and variety of social interactions. We found that (a) social interactions were more likely to be depicted in dream than in wake reports, (b) aggressive social interactions were more characteristic of REM than NREM or wake reports, and (c) dreamer-initiated friendliness was more characteristic of NREM than REM reports. We conclude that processing of, or simulations about, selected social interactions is preferentially performed while "off-line" during the dream state, with the REM state specializing in simulation of aggressive interactions and the NREM state specializing in simulation of friendly interactions.     

Masculine girls and feminine boys: genetic and environmental contributions to atypical gender development in early childhood

In this genetic study of atypical gender role development, parents of 5,799 twin pairs, ages 3 and 4, rated their twin children's masculinity and femininity. Boys were selected as gender atypical if they were highly feminine (top 5%, 10%, or 15%) relative to other boys, and girls were selected if they were highly masculine relative to other girls. Gender-atypical boys and girls were each divided into 2 groups: fully gender atypical (e.g., feminine boys also low on masculinity) and partially gender atypical (e.g., feminine boys who are not low on masculinity). DeFries-Fulker (DF; J. C. DeFries & D. W. Fulker, 1985, 1988) extremes analysis yielded moderate group heritability and substantial shared environment effects for atypical gender role behavior. However, for fully gender-atypical girls, group heritability accounted for most of the variance, and shared environment had no effect. The results are discussed in light of past studies and potential implications for atypical gender development.     

Analysis of Recruitment Strategies: Enrolling Veterans With PTSD Into a Clinical Trial

This analysis evaluated the efficacy of a variety of recruitment methods employed in a medication trial in a veteran population. Recruitment and demographic data were collected over the course of a randomized controlled trial (RCT) assessing the efficacy of an experimental medication for posttraumatic stress disorder (PTSD). Multivariate logistic regression was used to identify demographic and recruitment variables predictive of consenting to participation in the trial. Data were collected for 1,050 potential study participants. As compared with individuals contacted by mail based on chart review, potential participants who were referred by a clinician were 3 times more likely to consent to participate, and individuals who responded to an advertisement were 5 times more likely to consent to participate. Females were more likely to respond to advertisements, whereas males were more likely to be referred. Those who were referred were significantly older than potential participants identified via the directed mailing. Clinician referral was the method most likely to lead to identifying an eligible and willing participant. When designing a recruitment plan for a clinical trial, factors such as the target sample and available staff should be carefully considered.     

Reliability measures in item response theory: Manifest versus latent correlation functions

For item response theory (IRT) models, which belong to the class of generalized linear or non‐linear mixed models, reliability at the scale of observed scores (i.e., manifest correlation) is more difficult to calculate than latent correlation based reliability, but usually of greater scientific interest. This is not least because it cannot be calculated explicitly when the logit link is used in conjunction with normal random effects. As such, approximations such as Fisher's information coefficient, Cronbach's α, or the latent correlation are calculated, allegedly because it is easy to do so. Cronbach's α has well‐known and serious drawbacks, Fisher's information is not meaningful under certain circumstances, and there is an important but often overlooked difference between latent and manifest correlations. Here, manifest correlation refers to correlation between observed scores, while latent correlation refers to correlation between scores at the latent (e.g., logit or probit) scale. Thus, using one in place of the other can lead to erroneous conclusions. Taylor series based reliability measures, which are based on manifest correlation functions, are derived and a careful comparison of reliability measures based on latent correlations, Fisher's information, and exact reliability is carried out. The latent correlations are virtually always considerably higher than their manifest counterparts, Fisher's information measure shows no coherent behaviour (it is even negative in some cases), while the newly introduced Taylor series based approximations reflect the exact reliability very closely. Comparisons among the various types of correlations, for various IRT models, are made using algebraic expressions, Monte Carlo simulations, and data analysis. Given the light computational burden and the performance of Taylor series based reliability measures, their use is recommended.