1 In Retrospect
When Jan Meyer and I presented some first thoughts on threshold concepts (TC s) at a symposium in Brussels in early September 2002, we were not intending to offer a comprehensively developed theory of student learning, like the infant Greek goddess Athena emerging full-grown and armed for battle from the brow of Zeus. Rather we were attempting, or hoping, to reframe our prevailing understandings somewhat by employing a different perspective of why students encounter trouble. Why do they get stuck? What precipitates such trouble? This purpose had been identified from our findings and discussions with HE educators during the large UK national ETL project on student learning environments. We decided it would be interesting to get into this a little more deeply.
One of my own concerns during this early work was to attempt to broaden the disciplinary range or repertoire that an educational analytic framework might feel permission to draw from. Beyond, and in addition to, the undoubtedly valuable psychological framings that dominated nascent higher education pedagogy in the latter half of the twentieth century, we drew on a wider set of disciplinary lenses to gain insights into the nature of student difficulty, to help us get into the particular trouble at hand. The knowledge corpora that eclectically informed our early papers – explicitly, or, on occasion, more tangentially – might arise from literature, anthropology, philosophy, theology, mythology, language, semiotics, art, architecture, even culinary science. As the work progressed and the community of scholars widened, an interesting and rich web of related ideas emerged from these fields and clustered around the seminal notion of threshold concepts: troublesome knowledge, transformation, conceptual integration, boundedness, liminality, affect, ontological shift, discursive shift, pedagogical uncertainty, the defended learner, Einstellung effect, Integrated Threshold Concept Knowledge, ambivalence, hybridity, and so forth.
As with all healthy academic practice the emerging literature on threshold concepts has attracted critique in terms of concept definition and recognition (e.g. Rowbottom, 2017; Stopford, 2021) and in terms of methodology (Barradell, 2013). Such challenge and engagement has been constructive and purposeful though certain critiques of concept organisation and structure (e.g. Rowbottom, 2007; O’Donnell, 2010) remain predicated on the classical Aristotelian (or positivistic) model that relies on the premise that typical category components are both necessary and sufficient for category membership. This classical view, which seeks sets of definitive characteristics encompassing all TC s, which are demonstrable and attestable, has been attacked by Murphy (2002). Dunn (2017, p. 30) also observes that:
This rigid reliance makes it almost impossible to find definitions for categories that are suitable for different ages and contexts and does not account for category members that are more typical than others, or for ‘fuzzy’ concepts.
(Eysenck & Keane, 2010)
Even Stopford’s engaging and thoughtful proposition, drawing on Wittgensteinian philosophy, to prioritise student certainty as the primary point of analysis, still reverts to a need for a ‘fundamental level of certainty’, an ‘existential certainty’ and a ‘solid foundation’ (Stopford, 2021, p. 165), that is redolent of a kind of essentialism, or logocentrism. Jan Meyer has argued persuasively for the need to take account of the variation and variability of individual student learning and the contexts in which it takes place. Murphy (2016) favours ‘prototype’ and ‘exemplar’ approaches to concept definition, but more recent ‘rhizomatic’ and semiotic approaches (Deleuze & Guattari, 1980; Lacković, 2020; Mac Giolla Rí, 2022) might offer a stronger model to cope with the complexity of individual learning (see below). Concepts, after all, are not really a set of
2 In Prospect – Double Trouble?
As catalogued in Flanagan’s excellent repository of Threshold scholarship (Flanagan, 2018), we now have access to thousands of commentaries on TC s, emanating from over 70 countries, from Ecuador to Vietnam, from Ukraine to China, from the Pacific Islands to the Palestinian Territories. Let’s be presumptuous for a moment, and brazenly entertain the notion that Thresholds scholarship might extend into the future for a little while yet, with more symposia perhaps and continued publishing by a younger generation of scholars around the world. My own two cents’ worth, as they say in the States, is that two dimensions will need to be addressed. The first cent, so to speak, will be the epistemic dimension. The second will concern the societal dimension.
2.1 Epistemic Complexity
Barnett (2004) argues that it would be irrational and self-defeating to assume that we can prepare a new generation of students to cope with uncertainty by establishing a new kind of certainty in the curriculum. As one means of accessing the troublesomeness of concepts and of investigating their meanings, a fruitful approach adopted by threshold scholars in recent years has been that of rhizomatic analysis. Semetsky (2007), in reference to Deleuze and Guattari’s (1980) metaphor of the rhizome with its emphasis (as a mode of knowledge) on multiplicity, connection and heterogeneity, had stated earlier that ‘the creation of concepts is a function of experience and is inseparable from affects and percepts’ (Semetsky, 2007, p. 197). Guattari (1979/2011, p. 171) had observed that ‘Any point whatsoever on the rhizome will be able to be connected to any other point … will not be formalized on the basis of a logical or mathematical metalanguage … will be able to allow semiotic chains of all kinds to connect [in addition to linguistic] … it will imply the implementation of various collective assemblages of enunciation’. Nataša Lacković, (2020) in her semiotic and ‘inquiry graphics’ approach to TC s builds on this proposition that concepts are ‘complex, ever-growing interpretative entities’ and employs the terms ‘rhizomatic concepts’ or ‘concept-rhizomes’. She speaks of the continuous ‘concept expansion’ (Lacković, 2020, p. 281) which operates in conceptual learning. Their meanings, like rhizomes, branch, cross and expand according to the interrelations of learners’ and teachers’ interpretations of conceptual stimuli, their individual experiences and specific learning contexts. Denise
they embed many integral concepts, which are integral for TC development and represent more concrete but also troublesome concepts. Threshold and integral concepts form a rhizomatic concept network. This network helps our understanding of how concepts in a domain (here: social care) are not standalone entities but form connections with and between themselves and threshold concepts (TC s) within a wider rhizomatic network of disciplinary concepts, programmes, learners’ and teachers’ experiences and interpretations.
(Mac Giolla Rí, 2022, p. III)
The ‘threshold rhizome’ (TR) she posits, represents a series of interconnected threshold concepts and integral concepts (IC s). It is the troublesome process of negotiating and making connections between TC s and IC s within the rhizome structure, she argues, that provokes the liminal state. Once understood, the threshold rhizome becomes bounded, serving to change discourse and leading to ontological transformation. However, these states are dynamic and volatile. Concepts can become unstable and troublesome when certainty is undermined, suggests Mac Giolla Rí (2022, p. 130):
From a rhizomatic perspective, all these concepts can decay, with new roots and connections formed in their place from their residue. The residue introduced here as a metaphor means having remnants of the past influencing conceptualisation, reflecting Blunden’s (2012) articulation that concepts are embodied with meaning originating from the past.
These rhizomatic and semiotic threshold analyses are complex, undoubtedly presenting a challenge to learner ‘action poetry’ approaches, yet they seem to offer a sophisticated attempt to capture and articulate the particular meld of cognitive difficulty, affect, ontological shift, disciplinary and social context, and individual interpretation of signs that are multimodal – visual, tactile as well as verbal – and continually expanding/decaying, in an attempt to get at and help resolve the trouble experienced by students in liminal states.
2.2 Societal Complexity
This epistemic complexity is compounded by current societal complexity. In various quarters of higher education at the time of writing, student learning seems to be overshadowed by a reluctance on the part of some students to



Adinkra symbol of Sankofa (from https://commons.wikimedia.org/wiki/File:SakofaTime2.jpg, reproduced under a Wikimedia Commons re-use license)
More threateningly, and worryingly from a perspective of enhancing student learning, those teachers whose aspiration it is to present transcendental knowledge and encourage students to entertain the possibility of altered perspectives, may find themselves getting into trouble, being reported, sanctioned and in extreme cases (where institutional management is egregiously pusillanimous) silenced or dismissed. At the time of writing such tendencies,
The philosopher John Gray warns that:
If you hold back from learning about deception and violence you won’t understand why we have the laws we do, or any system of law at all. Equally you can’t appreciate great works of literature if you resist depictions of the darker side of human life … The power of these works of art comes from their truthfulness, their unswerving fidelity to the enduring features of the human world. Anyone who shrinks from them is in effect refusing to explore what it means to be human.
(Gray, 2016)
The novelist Howard Jacobson (2016) similarly points out that ‘We are an entangled species. We are not to be unknotted easily. When we turn our backs on difficulty […] we turn our backs on who we are’. This links back to the complex rhizomatic nature of conceptual integration and the intricate entanglements of our ontological states. ‘If you are really preparing for groundlessness, preparing for the reality of human existence’ argues the Buddhist educator Pema Chodron (Chodron cited in hooks, 1994, p. 206):
you are living on the razor’s edge, and you must become used to the fact that things shift and change. Things are not certain and they do not last and you do not know what is going to happen. My teachers have always pushed me over the cliff …
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