Sage Journals: Discover world-class research

Abstract

The distinction between nomothetics and idiographics (and adjacent issues such as heterogeneities, generalizability, and ergodicity) is fundamental to a deeper understanding of personality-related phenomena and any psychological structures and processes in general. Thus, ignoring nomothetics and idiographics threatens the validity of inferences in personality and psychological science. As fruits from an EAPP-funded expert meeting, three articles (Phan et al., Kuper et al., and Modersitzki et al.) provide systematic accounts of nomothetics and idiographics from conceptual, methodological, and applied perspectives. Together, this tripartite article collection argues that nomothetics and idiographics (a) are each multi-faceted (i.e., are not uniform), (b) require nuanced interpretation and precise terminology, and (c) do not stand in opposition to each other but can be complementary and fruitfully integrated to enrich our understanding of psychological phenomena. In this mantle article, we explicate guiding motivations for addressing nomothetics and idiographics in the first place, provide more context and history on the issues involved, introduce and summarize main take-aways from the three articles, and conclude with a view on bigger picture issues and suggestions on ways forward. We also introduce and invite to join the recently founded Personality Consortium on Research in Idiographics and Nomothetics (PECORINO).

Plain Language Summary

Psychological research often distinguishes between “nomothetics” and “idiographics”, but there is a lack of understanding what exactly they (should) mean. This mantle article serves as both an introduction and a capstone to three articles that grappled with conceptual, methodological, and applies perspectives regarding different forms of nomothetic and idiographic research. Conclusions are that the terms are each used in different ways and encode different concepts, require nuance and careful interpretation, and can be integrated with each other.

Keywords

nomothetic idiographic inferences personalization personality

Introduction

This mantle article accompanies three articles (Kuper et al., 2024; Modersitzki et al., 2025; Phan et al., 2024) that arose from an expert meeting on “Dynamics of Personality: Integrating Nomothetic and Idiographic Approaches in a Synthetic Framework” funded by the European Association of Personality Psychology (EAPP). In 2021, 21 participants (11 invited experts, 6 organizers,¹ and 4 guests) came together virtually to discuss nomothetics and idiographics in personality psychology and how these could be better integrated. This event was followed by a preconference to the ECP20 (in Madrid in 2022) and by several smaller meetings. Different work groups headed by three of the organizers were formed to explore conceptual, methodological, and applied challenges associated with nomothetics and idiographics, as well as their possible integrations. Besides founding a new Personality Consortium on Research in Idiographics and Nomothetics (PECORINO),² the result of their work is three articles, for which this mantle article provides a frame. The three interlocking articles were written in such a manner that they build upon each other but each can also stand alone. Of course, the deepest and clearest understanding of nomothetics and idiographics would be achieved by considering all three articles jointly. Our goal here is to (a) explicate guiding motivations for addressing nomothetics and idiographics in the first place, (b) provide more context and history on the issues involved, (c) introduce the three articles, and (d) conclude with illuminating bigger issues and sketching ways forward.

Rationale: Issues and motivation

The terms nomothetic and idiographic are ubiquitous in psychology and beyond, and also of great importance to personality science. As can be seen in Figure 1(a) as a visualization of a search on Web of Science³ with “nomothetic* OR idiographic* (Topic),”⁴ articles with any one of these terms seem to be increasing across years, as are citations to them. Figure 1(b) replicates this trajectory using Google’s Ngram Viewer. Together, this seems to suggest a certain interest in or importance of the topic. However, there are different understandings, (re-)conceptualizations, and traditions of these terms which have emphasized different defining or discriminating aspects of nomothetics and idiographics (e.g., differences due to scientific disciplines and their focal concerns, inferential knowledge sought and gained, focal entities under study, aggregation practices, methods or data-analytical strategies employed). These issues have led to imprecise use of terms in the literature, hamper communication and integration, and eventually impede a strong and cumulative science of personality.

Figure 1.

Trajectories for “nomothetics” and “idiographics” as topics across time. Note. Panel (a): Number of publications (gray bars) and citations (black line). The figure was downloaded from Web of Science for the search query “nomothetic* OR idiographic* (Topic),” performed on March 11, 2025. It was converted to gray-scale for better readability. Years on the x-axis were manually replaced to increase readability. The rapid “dropdown” of publication numbers in 2025 is due to data only being available until March of 2025 at the time of downloading the figure. Panel (b): Search for “nomothetic, idiographic” (case-insensitive) in English corpus from the years 1800–2022 (with a smoothing parameter of 2), performed on March 11, 2025. “Idiographic” appears in red, and “nomothetic” in blue. See https://books.google.com/ngrams/graph?content=nomothetic%2Cidiographic&year_start=1800&year_end=2022&corpus=en&smoothing=2&case_insensitive=true.

With the advent of new technological advances that have made many forms of data collection more scalable, cost-efficient, and easier to obtain, certain types of data (e.g., passively mobile-sensed information), designs (e.g., intensive longitudinal), and analytical techniques (e.g., machine learning) are becoming more and more prevalent in (personality) psychology. Big(ger) data can result from sampling many variables from many individuals on many occasions, and such data enable us to populate and dissect Cattell’s (1946) data box as never done before. This also means that we need to put more effort into our intentions with the data, the questions we ask, and the conclusions we draw. Too often, there are mismatches between what we seek at a theoretical level (i.e., the questions we ask and the knowledge we intend to produce), the ways we do our empirical research (e.g., how we collect data and analyze it), and inferences or interpretations to be drawn from the research (i.e., the knowledge we have generated and continue to apply). However, these mismatches seldom result in discombobulation; on the contrary, they are difficult to detect as mismatches, often insidiously opaque or deeply embedded into our scientific practices. Only by shining a bright light on them—and by creating awareness that they exist, operate in many of our works, and have adverse consequences—can we begin to work towards a more precise understanding of how nomothetic and idiographic approaches inform what we know about personality-related phenomena. Working towards cumulative and integrative frameworks serving to describe, explain, predict, modify, and understand personality-related phenomena both at a general and individual level could advance the scientific understanding of personality in both psychology and other disciplines (e.g., behavioral ecology, philosophy, and sociology). For such frameworks to be devised and to bear fruits, we first need to dispel “contemporary confusions” (Robinson, 2011) and understand nomothetics and idiographics better. This was the spirit within which the three articles in this collection were written.

Origins: Context and history

The nomothetic–idiographic distinction was originally coined by German philosopher Wilhelm Windelband and then introduced to psychology by Hugo Münsterberg,⁵ whose work influenced the differential psychologist William Stern (Hurlburt & Knapp, 2006). Gordon Allport, in turn, was influenced by both Windelband and Stern in his earlier use of the nomothetic–idiographic distinction and brought the distinction into personality psychology (Krauss, 2008; Robinson, 2011), though he later forwent using those terms. Later scholars continued to be influenced by Allport and other derivations from the original nomothetic–idiographic distinction—in fact, to such an extent that the original use of the terms has become either forgotten or misconstrued. To set the stage for the three articles in our collection, we here very briefly provide a historical sketch of the (multiple) origins of the nomothetic–idiographic distinction.

Wilhelm Windelband first introduced the terms nomothetic and idiographic in a speech at the University of Strasbourg in 1894. The term nomothetic is derived from the Ancient Greek νόμος (nómos) “law” and θέσις (t^hésis) “position, statement,” and the term idiographic from ἴδιος (ídios) “one’s own, private, distinct, specific” and γράφειν (gráp^hein) “to draw, sketch, write.” In accordance with their etymologies, Windelband used these terms to distinguish between the natures of intended knowledge typically sought by different scientific disciplines: either “laws stated” (nomo-thetics) or “specifics sketched” (idio-graphics). According to Windelband (1894/1998, p. 13), the natural sciences (Naturwissenschaften) are nomothetic “sciences of law” because they seek knowledge that concerns “the general in form of the natural law… [or] what always is.” Unveiled generalities can then be used to derive theories (Krauss, 2008; Robinson, 2011). The humanities (Geisteswissenschaften) are idiographic “sciences of specific incidences” because they seek knowledge concerning “the particular… [or] what once was” (Windelband, 1894/1998, p. 13), that is, specific or unique phenomena (Krauss, 2008). Notably, Windelband introduced the nomothetic–idiographic distinction in part because he felt that the emerging discipline of empirical psychology—a science of the human mind—could not be easily classified as either a natural science or a humanity (Lamiell, 1998). Based on its subject matter, psychology would be more akin to the humanities, while its objectives and goals paralleled those of the natural sciences. This issue—and inherent mismatches—was also recognized by other philosophers, such as Wittgenstein (1953, XIV, emphasis in original) who wrote aptly:

The confusion and barrenness of psychology is not to be explained by calling it a “young science”; its state is not comparable with that of physics, for instance, in its beginnings. (…) For in psychology there are experimental methods and conceptual confusion. (…) The existence of the experimental method makes us think we have the means of solving the problems which trouble us; though problem and method pass one another by.

The original Windelbandian nomothetic–idiographic distinction is one between two principal research objectives or inferential goals; it is not about certain topics or methodologies. It essentially concerns “the nature of the sought-after knowledge” (Lamiell, 1998, p. 12) and thus targets (the kinds of) inferences we are trying to make (or not). Both the natural sciences and the humanities can be concerned with general laws and specific phenomena (Robinson, 2011). In fact, the very same phenomenon can be approached both nomothetically and idiographically (Windelband, 1894/1998), and the two types of knowledge are usually complementary (Hurlburt & Knapp, 2006). Indeed, Allport (1937, 1961, 1962) believed that (personality) psychology should embrace and combine both nomothetic and idiographic approaches.

In line with Windelband, Stern (1911) used the nomothetic–idiographic distinction to differentiate between research aimed at generating general versus specific knowledge. For him, nomothetic meant examining between-person variability and covariances of variables. Such knowledge resides at the level of groups (or samples or populations) rather than individuals. On the other hand, idiographic captured, to him, examining particular individuals (e.g., psychobiography). The distinctions he made reflected a deviation from Windelband’s original meaning of idiographics which could seek knowledge about anything particular (e.g., a certain group or population, a special event) and not only a single individual. However, at the same time, Stern’s idea of idiographics can also include generalizations about the specific individual examined, such as personal dispositions (Lundh, 2015)—and thus generalizations (about a specific person) are not excluded from his conception of idiographics.

Allport was aware of Windelband’s original definitions but mostly went with Stern’s interpretation. Though it was Allport who “imported” the nomothetic–idiographic distinction into Anglo-American personality psychology, he loosely operated with the terms. Vagueness and loose operation regarding the terms nomothetic and idiographic are, unfortunately, still rampant today, as are many misconceptions around their distinction. This is exactly what the article collection, which we briefly summarize in the next section, attempts to address head-on.

The article collection on nomothetics and idiographics

Conceptual work group: Phan et al

Conceptual confusions surrounding nomothetics and idiographics are widespread. This state has been lamented several times before (e.g., Robinson, 2011), but psychology has yet to adopt a clear, systematic, and agreed-upon understanding of nomothetics and idiographics. During our expert meeting(s), we noticed there were at least four common issues when talking or reading about nomothetics and idiographics: (a) everyone has a similar “grasp” of the concepts, but what they mean in detail is different; (b) those differences stem from scholars using different terminology for the same phenomenon but also because they refer to actually different phenomena; (c) an implicit assumption seems to be that nomothetics and idiographics are mutually exclusive or difficult to truly combine; and (d) another assumption is that nomothetics and idiographics may be associated with particular topics or methodologies (designs and analyses).

Issues a and b have already been recognized in the literature which started to distinguish between different forms of nomothetics—such as Wundtian and (Neo-)Galtonian (e.g., Danziger, 1987, 1990; Lamiell, 1998; Robinson, 2011)—as well as new blendings such as “idiothetics” (Lamiell, 1981). The problem is that these terms are not widely known and hence likely not generally accepted (yet). Additionally, the phenomena these terms encode have not yet been integrated into a coherent framework that structures them and makes their relations to each other explicit. The article by Phan et al. seeks to bring these concepts more into mainstream personality psychology by providing much-needed systematicity.

Issues c and d are less recognized in the literature. False dichotomies are often propagated that pit supposedly “nomothetically oriented” research (equated or conflated with between-person, static, dimensional, structure, quantitative, or variable-centered/oriented foci) against supposedly “idiographically oriented” research (equated or conflated with within-person, dynamic, process, qualitative, person-centered/-oriented/-specific foci). The article by Phan et al. seeks to dispel these dichotomies by conceiving of different types of nomothetics and idiographics that go beyond studying specific topics or using particular methodologies and that require attention to fine-grained options in the entire research process. In fact, a key argument is that neither subjects of a study (e.g., structures or dynamics) nor methodologies used (e.g., quantitative or qualitative data) inherently determine whether an approach is nomothetic or idiographic.

Phan et al. make three key contributions to the literature. First, they systematically review how nomothetics and idiographics as terms and concepts have been used previously. Second and based on that review, they systematize the extracted concepts into a larger 2 × 3 framework that shows the breadth of possible personality-psychological research. Specifically, all major conceptualizations of nomothetics and idiographics within psychology can be captured by crossing (i) the focal entity for which insights are sought (person vs. population) with (ii) the intent to generalize (none vs. generalization for only one entity vs. generalization across several entities). This crossing results in six “types” of insights and knowledge we may be interested to gain. Importantly, not all of them have been identified as being “clearly” nomothetic or idiographic, and some are rarely encountered in personality psychology (so far). Third, Phan et al. correctly alert us that we need to be concerned with the entire empirical research process (questions → inputs → analyses → outputs → inferences) because there are multiple potentials for mismatches (e.g., between the knowledge we intended to gather and the inferences we make based on the findings of a study). To provide more systematicity and nuance, Phan et al. collated a set of 25 polychotomous criteria that should facilitate awareness for the different options and highlight how the gestalt of a research endeavor as “more or less nomothetic or idiographic, respectively” will be more a matter of degree rather than a dichotomous classification. Overall, Phan et al. aim to clarify and systematically structure the meaning of nomothetics and idiographics in empirical investigations. Notably, while their article is couched in personality psychology, their ideas extend to psychology as a whole.

Methodological work group: Kuper et al

The article by Kuper et al. operates on the assumption that nomothetics and idiographics—and the suitabilities of designs, data, and analytical strategies for different types of inferences—are better conceived of as existing in degrees rather than being strictly categorical. Further, often a given empirical study bears the potential for both more nomothetic and more idiographic inferences to be drawn and even integrated (e.g., Wright & Zimmermann, 2019).

Zooming in on some of the polychotomous criteria also discussed by Phan et al., Kuper et al. specifically outline 16 different methodological decisions in the domains of (1) research questions, (2) research designs, and (3) analyses and interpretations, which allow gauging matches between methodology and research questions as well as inferential goals. By making the different options (and forking paths) explicit, researchers can make these methodological decisions more intentionally.

Kuper et al. also systematize how levels of aggregation in analysis choices relate to different entities and generalities. Broadly, they distinguish between statistical approaches that are (a) person-specific, (b) population-specific, or (c) integrative. Person-specific approaches use N = 1 analyses (e.g., time series analysis applied to data from just one person), while population-specific approaches do not model any person-specificity (e.g., cross-sectional inter-individual associations; within-person phenomena modeled to be identical across persons). Integrative approaches can encompass repeated N = 1 analyses with bottom-up integration (i.e., working from several pieces of person-specific knowledge to more generalized knowledge across persons) or single population models with top-down integration (i.e., model-based inter-individual differences in within-person phenomena; e.g., random slopes in multilevel models). This system shows how different “types” of insights and knowledge as outlined in Phan et al. might be mapped onto, or uncovered in, different statistical approaches. Importantly, Kuper et al. also provide an overview of a range of statistical approaches and examples for their application at different levels of aggregation (e.g., regression analysis, multilevel modeling, factor analysis, network models, profile analyses, dynamic systems analyses, and machine learning). Such broad statistical approaches can often be used for person-specific, population-specific, or integrative purposes. Thus, a given method does not directly dictate to what extent a given research output (or entire research endeavor) is nomothetic or idiographic. To the contrary, several designs and analytical choices even allow drawing complementary nomothetic and idiographic insights.

Personalization work group: Modersitzki et al

The article by Modersitzki et al. links the nomothetics–idiographics topic to personalization as “the deliberate process of tailoring something to the individual person or a specified group of people with the ultimate goal of optimizing a desired outcome” (p. 4). After first reviewing how personalization relates to similar concepts in psychology and other disciplines, they argue for a person-specific perspective that places the person or individual (back) at the heart of personality psychology (e.g., Molenaar, 2004; Renner et al., 2020). Personality psychology is not just a psychology of variables or constructs but has been cast as a field concerned with whole persons (McAdams, 1997a, 1997b; Morf, 2002; Renner & Laux, 2000) as well as individuality and uniqueness (de Raad, 2020; see also Kaiser et al., 2024). Accordingly, a core tenet of Modersitzki et al.’s treatise is that personality-related phenomena are located and operate in individuals (not in populations or “average persons”; see Lamiell, 2019). They remind us of the principles of ergodicity (Molenaar, 2004) and how certain conditions need to hold to be able to properly draw inferences about individuals from knowledge about populations: Personality-related phenomena would need to be uniform across persons (homogeneity) and time (stationarity) for between-person findings (residing at population levels) to be fully applicable to single persons (residing at individual levels). Of course, these strict conditions are likely rarely met (Fisher et al., 2018; Speelman et al., 2024; cf. Adolf & Fried, 2019), which questions the extent to which many findings from personality psychology—hailing mostly from individual differences perspectives where the same (set of) constructs and measures are applied to many persons and assumed to mean the same things or operate in the same ways across persons—could be used to truly understand individuals (not aggregates, average persons, or populations; see also Moeller, 2022). Hence, the individual ought to be a focal unit of analysis in personality psychology, as is realized in person-specific perspectives and approaches.

Modersitzki et al. argue that personalization can be leveraged to inform three key goals of personality psychology (Mõttus et al., 2020): describing, predicting, and explaining personality-related phenomena. Beyond these, the authors also elaborate on how changing experiences and behavior may be informed by personalization (e.g., Matz et al., 2024), thus bridging the gap between more basic and applied research and also stepping into practice (e.g., implications for changes in personality characteristics due to interventions, coachings, psychotherapy, etc.). One way of personalizing description would be to find consistent person-specific patterns that characterize the individual (idiographic traits: Beck & Jackson, 2020; personal dispositions: Allport, 1937). In a similar vein, also prediction, explanation, and change can benefit from personalization. For example, person-specific models can be built to maximize predictive abilities and accuracy at the individual level (see, e.g., Beck & Jackson, 2022). Similarly, explanatory causal relations can be sought at the level of the individual person as antecedent−consequence relations may differ between persons (i.e., different antecedents may be connected to different consequences in different ways for different persons), and there is a certain tension between establishing causality at the population and at the individual level (see, e.g., a pertinent discussion in the field of epidemiology in Maldonado & Greenland, 2002, and especially the commentary by Elwert & Winship, 2002). Lastly, interventions to instill change may suffer from a “one-size-fits-all” approach lest different forms of personalization be taken into account (Matz et al., 2024). Modersitzki et al. provide a mapping of different approaches to personalizing interventions (matching of interventions based on individual differences; adaptive changes based on within-person data; person-specific tailoring) to major perspectives in personality psychology (cross-sectional inter-individual differences or differential variable-centered perspective; normative or differential person-centered perspective; person-specific perspective). This ties together basic and applied research and shows the potential of personality psychology for addressing real-world problems and policy issues (e.g., Almlund et al., 2011; Bleidorn et al., 2019; Hogan & Sherman, 2020).

Synthesis: Bringing the three articles together

The three articles by Phan et al., Kuper et al., and Modersitzki et al. contain each several systematizations—some developed independently and some jointly with each other.⁶ These are mostly synchronized with each other, but the articles were written such that each can be read and stand on its own. To provide a synthesis for readers to better grasp at one glance how the three articles “work together,” we have collated corresponding key pieces of insights in Table 1. Specifically, Phan et al.’s 2 × 3 (focal entity × generalization intent) foundational framework on research approaches on types of nomothetics and idiographics is linked to Kuper et al.’s system of person-specific, population-specific, and integrative data-analytical approaches as well as to Modersitzki et al.’s different forms of personalization. Table 1 also supplies synonyms in the literature, examples, and whether (and by whom) each form has been identified as nomothetic or idiographic. We hope that this overview can help readers structure and navigate the many issues nomothetics and idiographics touch.

Table 1.

Overview of Types of Nomothetics and Idiographics.

Inference^a			Example methodological approaches and labels	Associated statistical analyses^b	Applied potentials^c	Nomothetic or idiographic identification^d
Focal entity/entities (inferences concern …)	Generalization	Product
Specific individual person	None explicitly	Person portrayal (may incorporate person-specific patterns/laws)	Case study	None necessarily (but may incorporate descriptive person-specific analysis)	–	Idiographic: Allport (1937, 1962) Windelband (1894/1998)
	None explicitly		Psychobiography (largely qualitative)		–	Idiographic: Allport (1937, 1962) Windelband (1894/1998)
	From a sample of occasions within the person to a population of occasions	Person-specific patterns and laws	N = 1 research	• Person-specific analysis (N = 1 models)	An intervention can be tailored to the specific person and their unique processes (deep personalization)	Idiographic: Conner et al. (2009) Paunonen and Jackson (1985) Nomothetic: Windelband (1894/1998)
		Person-specific patterns and laws	N = 1 research	• Person-specific estimates partly informed by the population (top-down integration with model-based individual differences)
Multiple individuals (e.g., most, all)	From multiple individuals in a sample to other individuals (e.g., most, all) from the same population	Patterns and laws for each individual	Wundtian approach^e	• Repeated N = 1 analysis with quantitative or qualitative bottom-up integration (most aligned with the intended inference)	One-size-(actually-)fits all: Interventions can be developed for and effectively implemented in multiple (e.g., most, all) persons	Nomothetic: Lamiell (1998) Paunonen and Jackson (1985) Windelband (1894/1998)
Multiple individuals (e.g., most, all)		Patterns and laws for each individual	Wundtian approach^e	• Top-down integration: Single population model allowing to estimate the generalizability of (and individual differences in) within-person phenomena
Specific population	None explicitly	Population portrayal (may incorporate population-specific patterns/laws)	Ethnography (largely qualitative)	None necessarily	–	Idiographic: Windelband (1894/1998)
	From a sample of persons to the entire population	Population-specific patterns and laws	(Neo-)Galtonian approach^e Psychodemography^f	• Inter-individual analysis:	• Average intervention effects (when implemented repeatedly across the population) can be estimated based on:	Nomothetic: Allport (1937, 1962) Conner et al. (2009) Pelham (1993) Windelband (1894/1998)
				– Cross-sectional analyses	– differences between intervention and control groups (RCT)
				– Between-person analyses	– average within-person effects (pre-post)
				• Within-person analysis:	• Interventions can be matched to (groups of) targets based on:
				– Average within-person phenomena (while accounting for model-based individual differences with top-down integration)	– cross-sectional individual differences
				– Within-person phenomena modeled to be identical across persons	– individual differences in within-person patterns (surface personalization)
					• Interventions can be dynamically selected or adjusted for the individual based on intra-individual changes (adaptive personalization), using a normative within-person model
Multiple specific populations/mega-population of specific populations	From multiple specific populations to other populations (e.g., most, all from the mega-population) or from a sample of specific populations to the entire mega-population	Patterns and laws for each specific population or mega-population-specific patterns and laws	Cross-population (e.g., cross-cultural)	Similar distinctions as for analyses of individuals could be made (e.g., top-down integration: Model-based differences between specific populations vs. bottom-up integration of single-population analyses)	• Insights and strategies for a specific population (see above) could potentially be applied to other populations (if they generalize)	Nomothetic: Windelband (1894/1998)
			Cross-population (e.g., cross-cultural)		• Limited generalizability across populations indicates the need to account for population-specificity (e.g., culturally sensitive interventions)	Nomothetic: Windelband (1894/1998)

Note. Populations represent people in the aggregate rather than individually.

^aDistinction of research approaches by Phan et al.

^bKuper et al. discuss statistical approaches and provide examples.

^cModersitzki et al. discuss applied potentials and provide examples.

^dSee also Phan et al.

^eSee Danziger (1990).

^fSee Lamiell (2019).

Coda

Big(ger) pictures

This mantle article necessarily glosses over many of the finer details outlined in Phan et al., Kuper et al., and Modersitzki et al. to provide an overarching frame for them. Within this purview, we want to draw attention to four “big picture” points: (1) the focal scope of personality psychology, (2) the centrality of nomothetics–idiographics, (3) the use of the terms nomothetic and idiographic, and (4) the practice of engaging in (more) nomothetic or idiographic forms of inquiry or research.

Focus

What are we actually interested in and examining in personality psychology? Too rarely, we pause to (re-)examine our epistemic goals and topics, but grappling with nomothetics and idiographics affords a unique opportunity for reflection and focus. On a meta-perspective, the issues of nomothetics and idiographics are intimately tethered to the grand purview of personality psychology as being concerned with how “[e]very [person] is, in certain respects, a. like all other [persons], b. like some other [persons], c. like no other [person]” (adapted from Kluckhohn & Murray, 1953, p. 53). In other words, personality psychology deals with generalities, individual differences, and uniquenesses in bio-psycho-social characteristics, structures, and processes. Doing justice to this broad scope will necessarily entail devising theories and conducting research within all rows of Table 1. While the three articles showcase the richness of what personality psychology can be about and how it can inform real-world issues, undeniably modern personality psychology seems to have predominantly focused only on a few of the available rows of Table 1 (especially those concerning inter-individual differences) and thus inadvertently narrowed the usual scope of the field. Of course, some cells of Table 1 may be deemed more “interesting,” “worthwhile,” or “useful” than others, though such judgments may be tied to subjective valuations, zeitgeist trends, and broader systemic issues (e.g., funding and politics). Confronting the topic of nomothetics–idiographics can open us up to hitherto neglected ways of studying personality and related phenomena—and thus broaden our perspectives on which approaches in the cells may be more or less valuable (when, why, for whom, and for which purposes; see also our thoughts in Practice). Thus, to reclaim personality psychology’s full(er) scope, Table 1 can be informative as to where more efforts could be concentrated in the future.

Centrality

Why is it important to come to grips with topics revolving around nomothetics and idiographics? Besides (re-)opening many more doors into personality psychology (Allport, 1946, pp. 133–134; see also Focus previously), several topics—including but not limited to personality dynamics (Jayawickreme et al., 2021; Kuper et al., 2021; Quirin et al., 2020) or the whole person (McAdams, 1997a; Renner & Laux, 2000)—will require more concern with nomothetics and idiographics. Nomothetics–idiographics is not just an abstract, epistemic concern but has practical consequences also: Heterogeneities, lack of generalization, and ergodicity boundaries can limit, or at least alter, what we (think we) know about personality-relevant phenomena and how they operate—and what we (think we) know is proposed to have policy relevance (e.g., Bleidorn et al., 2019) and could be applied in interventions (e.g., Matz et al., 2024). Therefore, we need a better grasp of what we know and how we (should) come to know it. Contending with nomothetics-idiographics (and surrounding issues) achieves just that. Thus, nomothetics and idiographics—and how we deal with them—are central and vital to how we think and act scientifically within personality psychology (and beyond).

Terms

Should we abandon the terms nomothetic and idiographic? Even the scholars from our expert meeting espoused different opinions,⁷ and we think it is instructive to make this transparent here. Roughly, opinions range between “We should not use these terms anymore because they do more harm than good,” to “We should use the terms as Windelband envisioned them,” to “We should likely devise new terms,” to “We can still use the terms but should be extremely precise in each case what exactly they mean.” The last recommendation might be the most reconciling one, especially because precision in scientific communication should be our default. It further squares well with recent calls for more consensus-building in (personality) psychology (Leising et al., 2024). In this vein, we hope that readers (and we) can at least agree on the different concepts and issues laid out in Table 1. Because our terminologies and preferences may (still) vary in some cases, we need to commit more to precision and transparency in our communications and partake in ongoing dialog to work towards more consensus (or at least identify where we agree and where not).

Practice

Which approaches should we use—more nomothetic, more idiographic, or integrative ones? Much like a hammer and screwdriver are devised for specific purposes, the different rows in Table 1 are tools that get different jobs done. No job is inherently better or worse than the other; they are just different jobs that require specific tools to solve them. The important thing is not to use a hammer when you need a screwdriver and vice versa; but for a complex project, maybe both are needed. With this in mind, we remind readers that the polychotomies offered by Phan et al. and Kuper et al. can help clarify goals, select appropriate research methodologies, avoid mismatches (e.g., between intended insights and output), and enhance clear communication. We thus recommend that researchers go through applicable polychotomies for their (intended or already conducted) research to gain a clearer understanding on where on the nomothetics–idiographics space their research may lie. A thusly achieved deeper understanding can spur revolutions needed in how we construct theories, select methods, and tether both (Moeller, 2022).

Prospects

We hope the tripartite article collection drives home the following points on nomothetics and idiographics:

They are each multi-faceted and cannot be easily reduced to simplified standard practices.

They each require nuanced interpretation and precise terminology.

They need not preclude or even stand in opposition to each other but can be integrated, used jointly, and complement each other.

By considering different possibilities or options of nomothetic and idiographic approaches, a richer understanding of personality (and any psychological structures or processes, in fact) can be achieved.

To honor these take-home messages and work towards such a richer understanding, we invite other researchers to build upon them and contribute to a consortium that was formed after several exchanges among the members of the expert meeting: The Personality Consortium on Research in Idiographics and Nomothetics (PECORINO). PECORINO is intended as a platform and forum on nomothetics–idiographics (and adjacent topics) to collate information and resources (e.g., articles, slides, and teaching materials), facilitate networking and communication between like-interested scholars, and coordinate events (e.g., meetings, workshops, and preconferences) and collaborations (e.g., on existing or new projects). We hope that the consortium and the three articles on nomothetics and idiographics can serve as a foundation from which to build further discussions on points of consensus (or dissensus) and work towards a more integrated understanding of personality (and other psychological structures and processes) at both individual and group levels.

Footnotes

Author contributions

JR: Conceptualization and writing—original draft (lead); LVP: Writing—original draft (supporting) and writing—review and editing; NK: Writing—review and editing; NM: Writing—review and editing; MQ: Writing—review and editing.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Niclas Kuper

Nick Modersitzki

Notes

References

Adolf

J. K.

Fried

E. I.

(2019). Ergodicity is sufficient but not necessary for group-to-individual generalizability. Proceedings of the National Academy of Sciences of the United States of America, 116(14), 6540–6541. https://doi.org/10.1073/pnas.1818675116

Allport

G. W.

(1937). Personality: A psychological interpretation. Holt.

Allport

G. W.

(1946). Personalistic psychology as science: A reply. Psychological Review, 53, 132–135. https://doi.org/10.1037/h0058477

Allport

G. W.

(1961). Pattern and growth in personality. Holt, Reinhart & Winston.

Allport

G. W.

(1962). The general and the unique in psychological science. Journal of Personality, 30(3), 405–422. https://doi.org/10.1111/j.1467-6494.1962.tb02313.x

Almlund

Duckworth

Heckman

Kautz

(2011). Personality psychology and economics. In Hanushek

E. A.

Machin

Wößmann

(Eds.), Handbook of the Economics of Education (4, pp. 1–181). Elsevier. https://doi.org/10.1016/b978-0-444-53444-6.00001-8

Beck

E. D.

Jackson

J. J.

(2020). Idiographic traits: A return to allportian approaches to personality. Current Directions in Psychological Science, 29(3), 301–308. https://doi.org/10.1177/0963721420915860

Beck

E. D.

Jackson

J. J.

(2022). Personalized prediction of behaviors and experiences: An idiographic person-situation test. Psychological Science, 33(10), 1767–1782. https://doi.org/10.1177/09567976221093307

Bleidorn

Hill

P. L.

Back

M. D.

Roberts

Hennecke

Hopwood

C. J.

Jokela

Kandler

Lucas

R. E.

Luhmann

Orth

Wagner

Wrzus

Zimmermann

(2019). The policy relevance of personality traits. American Psychologist, 74(9), 1056–1067. https://doi.org/10.1037/amp0000503

10.

Cattell

R. B.

(1946). Description and measurement of personality. World Book Company.

11.

Conner

T. S.

Tennen

Fleeson

Barrett

L. F.

(2009). Experience sampling methods: A modern idiographic approach to personality research. Social and Personality Psychology Compass, 3(3), 292–313. https://doi.org/10.1111/j.1751-9004.2009.00170.x

12.

Danziger

(1987). Statistical method and the historical development of research practice in American psychology. In The probabilistic revolution, Vol. 1: Ideas in history; Vol. 2: Ideas in the sciences (pp. 35–47). The MIT Press.

13.

Danziger

(1990). Constructing the subject: Historical origins of psychological research (1st ed.). Cambridge University Press. https://doi.org/10.1017/CBO9780511524059

14.

de Raad

(2020). Individuality and personality. In Pawlik

d’Ydewalle

(Eds.), Psychological concepts (pp. 299–323). Psychology Press.

15.

Elwert

Winship

(2002). Commentary: Population versus individual level causal effects. International Journal of Epidemiology, 31(2), 432–434.

16.

Fisher

A. J.

Medaglia

J. D.

Jeronimus

B. F.

(2018). Lack of group-to-individual generalizability is a threat to human subjects research. Proceedings of the National Academy of Sciences of the United States of America, 115(27), E6106–E6115. https://doi.org/10.1073/pnas.1711978115

17.

Hogan

R. T.

Sherman

R. A.

(2020). Personality theory and the nature of human nature. Personality and Individual Differences, 152, Article 109561. https://doi.org/10.1016/j.paid.2019.109561

18.

Hurlburt

R. T.

Knapp

T. J.

(2006). Münsterberg in 1898, not Allport in 1937, introduced the terms ‘idiographic’ and ‘nomothetic’ to American psychology. Theory & Psychology, 16(2), 287–293. https://doi.org/10.1177/0959354306062541

19.

Jayawickreme

Fleeson

Beck

E. D.

Baumert

Adler

J. M.

(2021). Personality dynamics. Personality Science, 2, Article e6179. https://doi.org/10.5964/ps.6179

20.

Kaiser

Killin

Abendroth

Baune

B. T.

Bilstein

Breitmoser

Caspers

B. A.

Gadau

Gossmann

T. I.

Kaiser

Krüger

Kurtz

Lengersdorf

Malsch

A. K. F.

Müller

Rauthmann

J. F.

Reinhold

Richter

S. H.

Wittmann

(2024). Individualisation and individualised science across disciplinary perspectives. European Journal for Philosophy of Science, 14(3), 41. https://doi.org/10.1007/s13194-024-00602-8

21.

Kluckhohn

Murray

H. A.

(1953). Personality Formation: The determinants. In Kluckhohn

Murray

H. A.

Schneider

D. M.

(Eds.), Personality in nature, society, and culture (pp. 53–67). Knopf.

22.

Krauss

(2008). A tripartite model of idiographic research: Progressing past the concept of idiographic research as a singular entity. Social Behavior and Personality: An International Journal, 36(8), 1123–1140. https://doi.org/10.2224/sbp.2008.36.8.1123

23.

Kuper

Andresen

P. K.

Beck

E. D.

Costantini

Hamaker

E. L.

Wright

A. G. C.

Zimmermann

(2024). From persons to general principles: Methodological decisions for idiographic and nomothetic research. European Journal of Personality, 39(4), 635–661. https://doi.org/10.1177/08902070241278020

24.

Kuper

Modersitzki

Phan

L. V.

Rauthmann

J. F.

(2021). The dynamics, processes, mechanisms, and functioning of personality: An overview of the field. British Journal of Psychology, 112(1), 1–51. https://doi.org/10.1111/bjop.12486

25.

Lamiell

J. T.

(1981). Toward an idiothetic psychology of personality. American Psychologist, 36(3), 276–289. https://doi.org/10.1037/0003-066X.36.3.276

26.

Lamiell

J. T.

(1998). ‘Nomothetic’ and ‘Idiographic’: Contrasting Windelband’s understanding with contemporary usage. Theory & Psychology, 8(1), 23–38. https://doi.org/10.1177/0959354398081002

27.

Lamiell

J. T.

(2019). The entrenchment of statistical thinking in early twentieth century differential psychology. In Lamiell

J. T.

(Ed.), Psychology’s misuse of statistics and persistent dismissal of its critics (pp. 49–76). Springer International Publishing. https://doi.org/10.1007/978-3-030-12131-0_3

28.

Leising

Liesefeld

Buecker

Glöckner

Lortsch

(2024). A tentative roadmap for consensus building processes. Personality Science, 5. https://doi.org/10.1177/27000710241298610

29.

Lundh

L.-G.

(2015). The person as a focus for research. The contributions of Windelband, stern, Allport, Lamiell and magnusson. Journal for Person-Oriented Research, 1(1–2), 15–33. https://doi.org/10.17505/jpor.2015.03

30.

Maldonado

Greenland

(2002). Estimating causal effects. International Journal of Epidemiology, 31(2), 422–429.

31.

Matz

S. C.

Beck

E. D.

Atherton

O. E.

White

Rauthmann

J. F.

Mroczek

D. K.

Kim

Bogg

(2024). Personality science in the digital age: The promises and challenges of psychological targeting for personalized behavior-change interventions at scale. Perspectives on Psychological Science: A Journal of the Association for Psychological Science, 19(6), 1031–1056. https://doi.org/10.1177/17456916231191774

32.

McAdams

D. P.

(1997a). The case for unity in the (post)modern self: A modest proposal. In Ashmore

Jussim

(Eds.), Self and identity: Fundamental issues (pp. 46–78). Oxford University Press.

33.

McAdams

D. P.

(1997b). A conceptual history of personality psychology. In Hogan

Johnson

Briggs

(Eds.), Handbook of personality psychology (pp. 3–39). Academic Press.

34.

Modersitzki

Phan

L. V.

McDonald

Wright

A. G.

Renner

K.-H.

(2025). Personality psychology is getting personal: Advancing the field through personalization. European Journal of Personality. https://doi.org/10.1177/08902070251316915

35.

Moeller

(2022). Averting the next credibility crisis in psychological science: Within-person methods for personalized diagnostics and intervention. Journal for Person-Oriented Research, 7(2), 53–77. https://doi.org/10.17505/jpor.2021.23795

36.

Molenaar

P. C. M.

(2004). A manifesto on psychology as idiographic science: Bringing the person back into scientific psychology, this time forever. Measurement: Interdisciplinary Research & Perspective, 2(4), 201–218. https://doi.org/10.1207/s15366359mea0204_1

37.

Morf

C. C.

(2002). Personality at the hub: Extending the conception of personality psychology. Journal of Research in Personality, 36(6), 649–660. https://doi.org/10.1016/S0092-6566(02)00517-2

38.

Mõttus

Wood

CondonZimmermann

D. M. J.

(2020). Descriptive, predictive and explanatory personality research: Different goals, different approaches, but a shared need to move beyond the big few traits. European Journal of Personality, 34(6), 1175–1201. https://doi.org/10.1002/per.2311

39.

Paunonen

S. V.

Jackson

D. N.

(1985). Idiographic measurement strategies for personality and prediction: Some unredeemed promissory notes. Psychological Review, 92(4), 486–511. https://doi.org/10.1037/0033-295X.92.4.486

40.

Pelham

B. W.

(1993). The idiographic nature of human personality: Examples of the idiographic self-concept. Journal of Personality and Social Psychology, 64(4), 665–677. https://doi.org/10.1037/0022-3514.64.4.665

41.

Phan

L. V.

Modersitzki

Kuper

Beckmann

Fajkowska

Gollwitzer

Horstmann

K. T.

Quirin

Renner

K.-H.

Wright

A. G.

Rauthmann

J. F.

(2024). Beyond nomothetics and idiographics: Towards a systematization of personality research approaches. European Journal of Personality, 39(2), 233–253. https://doi.org/10.1177/08902070241301633

42.

Quirin

Robinson

M. D.

Rauthmann

J. F.

Kuhl

Read

S. J.

Tops

DeYoung

C. G.

(2020). The Dynamics of Personality Approach (DPA): Twenty tenets for uncovering the causal mechanisms of personality. European Journal of Personality, 34(6), 947–968. https://doi.org/10.1002/per.2295

43.

Renner

K.-H.

Klee

von Oertzen

(2020). Bringing back the person into behavioural personality science using big data. European Journal of Personality, 34(5), 670–686. https://doi.org/10.1002/per.2303

44.

Renner

K.-H.

Laux

(2000). Unitas multiplex, purposiveness, individuality: Contrasting Stern's conception of the person with Gergen's saturated self. Theory & Psychology, 10(6), 831–846. https://doi.org/10.1177/0959354300106008

45.

Robinson

O. C.

(2011). The idiographic/nomothetic dichotomy: Tracing historical origins of contemporary confusions. History & Philosophy of Psychology, 13(2), 32–39. https://doi.org/10.53841/bpshpp.2011.13.2.32

46.

Speelman

C. P.

Parker

Rapley

B. J.

McGann

(2024). Most psychological researchers assume their samples are ergodic: Evidence from a year of articles in three major journals. Collabra: Psychology, 10(1), 1597–1613. https://doi.org/10.1525/collabra.92888

47.

Stern

(1911). Die differentielle psychologie in ihren methodischen grundlagen. Barth.

48.

Windelband

(1998). History and natural science. Theory & Psychology, 8(1), 5–22. https://doi.org/10.1177/0959354398081001

49.

Wittgenstein

(1953). Philosophical investigations (2nd ed.). Basil Blackwell. Translated by G. E. M. Anscombe.

50.

Wright

A. G. C.

Zimmermann

(2019). Applied ambulatory assessment: Integrating idiographic and nomothetic principles of measurement. Psychological Assessment, 31(12), 1467–1480. https://doi.org/10.1037/pas0000685

Integrating nomothetics and idiographics in personality science and beyond

Abstract

Plain Language Summary

Keywords

Introduction

Rationale: Issues and motivation

Origins: Context and history

The article collection on nomothetics and idiographics

Conceptual work group: Phan et al

Methodological work group: Kuper et al

Personalization work group: Modersitzki et al

Synthesis: Bringing the three articles together

Coda

Big(ger) pictures

Focus

Centrality

Terms

Practice

Prospects

Footnotes

Author contributions

Declaration of conflicting interests

Funding

ORCID iDs

Notes

References