Maria Jimenez-Buedo

For years, the phenomenon of experimental reactivity (defined as the alteration of the subject’s behaviour as a result of their awareness of being studied) seemed to be of little or no concern to experimental economists. With their clear-cut methodological stance shaped by Vernon Smith’s list of precepts, economists could avoid the worries associated with subjects’ reactivity through a rigorous control over the incentives proposed by the experimental setting as designed in the game. More recently, as experimental economists gradually moved in their study towards topics in which economic incentives intermingled with normative considerations (such as in the study of altruism, punishment, or social norms), a corresponding interest in the problem of reactivity has ensued. This chapter offers an interpretation of this transit: it argues that the success of experimental economics and the unforeseen expansion of their object of enquiry into the realm of ethics and norm-related behaviour forces experimental economists to adopt some of the conceptual tools of psychologists. This ultimately undermined the economists’ initial methodological project, but this is the price to be paid to study the mechanisms of prosociality. This way, and regarding the pitfalls of reactivity, experimental economists are in the same predicament as fellow psychologists, philosophers, and other social scientists.

Following Goldman’s seminal work, most contemporary philosophical contributions on the novice-expert relation have adopted a normative, expert-focused approach. In this paper, we aim to shift the focus of the philosophical analysis towards the characteristics of the novices, and how they might determine the choices that experts make. On the bases of recent empirical evidence from social psychology, we discuss how novices evaluate the messages that they receive and distinguish diverse kinds of novices according to their competence in message assessment. Building on that analysis, we discuss the difficulties of approaches to expertise that focus only on the standpoint of novices or assume novices are homogeneous. In our analysis, we introduce the standpoint of experts, and we pay special attention to the heterogeneity of novices. This approach allows us to identify and address the difficulties faced by experts in the context of science communication. In the last part of the paper, we characterise and discuss the problem of experts when choosing a strategy in the issuing of a public campaign to advise or inform certain populations of novices.

The experimental revolution in the social sciences is one of the most significant methodological shifts undergone by the field since the ‘quantitative revolution’ in the nineteenth century. One of the often valued features of social science experimentation is precisely the fact that there are clear methodological rules regarding hypothesis testing that come from the methods of the natural sciences and from the methodology of RCTs in the biomedical sciences, and that allow for the adjudication among contentious causal claims. We examine critically this claim and argue that some current understandings of the practices that surround social science experimentation overestimate the degree to which experiments can actually fulfil this role as “objective” adjudicators, by neglecting the importance of shared background knowledge or assumptions and of consensus regarding the validity of the constructs involved in an experiment. We take issue with the way the distinction between internal and external validity is often used to comment on the inferential import of experiments, used both among practitioners and among philosophers of science. We describe the ways in which the more common use of the internal/external distinction differs from Cook and Campbell’s original methodological project, in which construct validity and the four-fold validity typology were all important in assessing the inferential import of experiments. We argue that the current uses of the labels internal and external, as applied to experimental validity, help to encroach a simplistic view on the inferential import of experiments that, in turn, misrepresents their capacity to provide objective knowledge about the causal relations between variables.

Reactivity, or the phenomenon by which subjects tend to modify their behavior in virtue of their being studied upon, is often cited as one of the most important difficulties involved in social scientific experiments, and yet, there is to date a persistent conceptual muddle when dealing with the many dimensions of reactivity. This paper offers a conceptual framework for reactivity that draws on an interventionist approach to causality. The framework allows us to offer an unambiguous definition of reactivity and distinguishes it from placebo effects. Further, it allows us to distinguish between benign and malignant forms of the phenomenon, depending on whether reactivity constitutes a danger to the validity of the causal inferences drawn from experimental data.

The article identifies a latent debate in the recent literature on the role and worth of experiments in economics and other social sciences concerning the relationship between the external and the internal validity of experimental designs. Our work identifies two incompatible views regarding the relationship between internal and external validity of experiments. While in the methodological literature references to the idea that there is a trade-off between the internal and external validity of experiments abound, this view coexists with the position stating that internal validity is rather a prerequisite of external validity. By identifying the contours of this implicit debate in the recent methodological literature around the use of experiments in the social sciences we call attention upon a series of insufficiently conceptualized issues regarding the central notions of internal and external validity and we question the standard view positing a trade-off between the two. This article stands against common associations of internal validity and external validity with the distinction between field and laboratory experiments and assesses critically the arguments that link the artificiality of experimental settings done in the laboratory with the purported trade-off between internal and external validity.

The advantage of examining causality from the perspective of modelling is thus that it puts us naturally closer to the practice of the sciences. This means being able to set up an interdisciplinary dialogue that contrasts and compares modelling practices in different fields, say economics and biology, medicine and statistics, climate change and physics. It also means that it helps philosophers looking for questions that go beyond the narrow ‘what-is-causality’ or ‘what-are-relata’ and thus puts causality right at the centre of a complex crossroad: epistemology/methodology, metaphysics, politics/ethics. This special issue collects nine papers that touch upon various scientific fields, from system biology to medicine to quantum mechanics to economics, and different questions, from explanation and prediction to the role of both true and false assumptions in modelling.

A series of recent debates in experimental economics have associated demand effects with the artificiality of the experimental setting and have linked it to the problem of external validity. In this paper, we argue that these associations can be misleading, partly because of the ambiguity with which “artificiality” has been defined, but also because demand effects and external validity are related in complex ways. We argue that artificiality may be directly as well as inversely correlated with demand effects. We also distinguish between the demand effects of experimentation and the reactions that they may trigger and that might endanger experimental validity. We conclude that economists should pay more attention to the way in which subjects construe the experimental task and learn to exploit subjects’ reactivity to expectations in their experiments

Not so long ago, many economists and philosophers felt that their disciplines had no use for experimental methods. An experimental study was, by its nature, ‘not economics’ or ‘not philosophy’ – psychology maybe. Opinion has changed dramatically. This issue of Economics and Philosophy represents a collection of recent contributions to experimental research that explicitly deal with empirical findings or methodological questions in the intersection of the two disciplines. To the best of our knowledge, it is the first such collection dedicated to addressing these common interests.

Much of the methodological discussion around experiments in economics and other social sciences is framed in terms of the notions of internal and external validity. The standard view is that internal validity and external validity stand in a relationship best described as a _trade-off_. However, it is also commonly held that internal validity is a _prerequisite_ to external validity. This article addresses the problem of the compatibility of these two ideas and analyzes critically the standard arguments about the conditions under which a trade-off between internal and external validity arises. Our argument stands against common associations of internal validity and external validity with the distinction between field and laboratory experiments and assesses critically the arguments that link the artificiality of experimental settings done in the laboratory with the purported trade-off between internal and external validity. We conclude that the idea of a trade-off or tension between internal and external validity seems, upon analysis, far less cogent than its intuitive attractiveness may lead us to think at first sight.

The Dictator Game, one of the best-known designs in experimental social science, has been extensively criticized, and declared by some to be defunct, on the grounds that its results are the product of a research artefact. Critics of the DG argue that the behaviour observed in the game is not the outcome of genuine pro-social preferences but must, instead, be interpreted as a response to the cues given by the experimental design, where these cues signal that the game is about ‘sharing’. Despite this criticism, the DG continues to be extensively used, and some have defended its validity as an instrument capable of measuring the role of social pressure and social norms against economic motivations. This article examines the assumptions implicit in the claim that the DG results are artefactual and spells out the conditions under which the game can be used to test hypotheses about pro-social...