When our students and colleagues hear the term “epistemic fluency” for the first time they usually ask us two common questions: “Is it about interdisciplinarity?”; “Is it about expertise?” Perhaps the most straightforward answer is: “Yes” and “Yes”. Epistemic fluency is about interdisciplinarity and about expertise. To put it short – epistemic fluency is a capacity that underpins interdisciplinary expertise. However, this answer warrants some explanation of what we mean by “interdisciplinarity” and what we mean by “expertise”.
In everyday use of the term “interdisciplinarity” its notion often covers the integration of knowledge and ways of knowing across several established disciplines, each of which demarcates a domain of specialised inquiry, such as biology and chemistry .
Thus, interdisciplinary understanding and skills are often associated with the capability to work across two or more disciplines by fusing their concepts, theories and methods (e.g., biochemistry) . Our adopted notion of interdisciplinarity, however, is broader. It also encompasses ways of knowing that are beyond formal disciplinary domains. That is, it includes what is often called “transdisciplinarity”: “the intercourse between (inter)disciplines and society” .
The central epistemological assumption that underpins our view of interdisciplinary expertise is the practical focus of interdisciplinary thinking, problem-solving and action on producing innovative knowledge that matters and enables to live more responsibly in the complex world. The Oxford Handbook of Interdisciplinarity nicely conveys very similar assumption of interdisciplinary knowledge and knowing:
“Interdisciplinarity represents an innovation in knowledge production – making knowledge more relevant, balancing incommensurable claims and perspectives, and raising questions concerning the nature and viability of expertise” .
Indeed, the question about expertise – including viability of expertise – is paramount. What does “expertise” mean? In in everyday language (and much of research on expertise development) the notion of expertise is primarily associated with specialisation in a particular, well defined domain and recognition of one’s knowledge and mastery by others within the same domain (aka. within specific “knowledge culture”) . Further, very notion of disciplinarity (and related to it disciplinary division of knowledge work) often builds on two paradigmatic assumptions about knowledge and how we know. First, “it is possible to get down to the bottom of the things, and that it is possible to study parts of the world in isolation from the world at large” . Therefore, “divide and conquer” rule that underpins disciplinary specialisation is one of the main principles for gaining understanding needed to solve complex problems in the world. Second, disciplinary scientific knowing often builds on a strong conviction that experimental control can produce valid and robust knowledge. That is, what is considered as valid knowledge, as Frodeman et al. nicely put it, is: “Robust results, but within self-contained bubble” .
If we adopt this view of knowledge and expertise, then the appropriateness of the word “expertise” for characterising knowledgeable and skilful interdisciplinary work, indeed, becomes questionable. Once this robust knowledge leaves constrained laboratory settings and enters an open world, the experimentally clean knowledge of the parts (and associated to them expertise) often has limited relevance to the world where many things interact and cannot be controlled.
Rather than abandoning the notion of expertise, in our book, we take rather different view of what expertise is and adopt a more dynamic, socially shaped and enacted perspective. Following Collins and Evans , we acknowledge that expertise includes various kinds and levels of specialised knowledge and performance: from “ubiquitous expertise” that exists broadly within a culture and can often be taken for granted, through “interactional expertise” that allows one to participate in a specialised discourse, to “contributory expertise” that allows one to actually do professional work. From our perspective,
“Expertise is skilful performance informed by particular kinds of knowledge and ways of knowing, recognised within a [dynamically changing] culture.” (Chapter 4)
This view recognises that experts’ interdisciplinary knowledge and knowing are inseparable from the embodied skill, knowledgeable action and, shaped by multiple disciplinary cultures, situated performance. Such performance demands not only formal disciplinary knowledge or formally recognised expertise in individual knowledge domains, and not only generic cognitive capabilities or general communication skills, but also practical mastery of concrete epistemic tools and functional ways of knowing that enable professionals to cross disciplinary boundaries by engaging in embodied, situated knowledge work in concrete material settings (Chapters 13-16) .
That is, the term “interdisciplinary expertise” is not a self-contradicting blend of two epistemologicaly irreconcilable ways of knowing. Rather, it points to a new kind of expertise that draws on a capacity that we call “epistemic fluency”:
“Epistemic fluency involves a set of capabilities that allow people to recognize and participate in different ways of knowing. Such people are adept at combining different kinds of specialised and context-dependent knowledge and at reconfiguring their work environment to see problems and solutions anew.” (Chapter 1)
 The Oxford English Dictionary provides only adjective (“interdisciplinary”) and defines “Interdisciplinary” as follows: “Of or pertaining to two or more disciplines or branches of learning; contributing to or benefiting from two or more disciplines.” [“interdisciplinary, adj.”. OED Online. September 2015. Oxford University Press. http://www.oed.com/view/Entry/97720. Accessed October 15, 2015.]
 For example, Boix Mansilla and Duraising provide the following definition of interdisciplinary understanding: “We define interdisciplinary understanding as the capacity to integrate knowledge and modes of thinking in two or more disciplines or established areas of expertise to produce a cognitive advancement – such as explaining a phenomenon, solving a problem, or creating a product – in ways that would have been impossible or unlikely through single disciplinary means” (p.219). [Mansilla, Veronica Boix, and Elizabeth Dawes Duraising. “Targeted Assessment of Students’ Interdisciplinary Work: An Empirically Grounded Framework Proposed.” The Journal of Higher Education, 78, no. 2 (2007): 215-237.]
 Frodeman, Robert, Julie Thompson Klein, and Carl Mitcham, eds. The Oxford Handbook of Interdisciplinarity. Oxford: Oxford University Press, 2010. p. XXX.
 Ibid, p. XXIX.
 Oxford English Dictionary defines “expertise” as follows: “Expert opinion or knowledge, often obtained through the action of submitting a matter to, and its consideration by, experts; an expert’s appraisal, valuation, or report”; “The quality or state of being expert; skill or expertness in a particular branch of study or sport.” [“expertise, n.”. OED Online. September 2015. Oxford University Press. http://www.oed.com/view/Entry/66556. Accessed October 15, 2015].
 Frodeman et al, p. XXXIX.
 Ibid, p. XXXIV.
 Collins, Harry, and Robert Evans. Rethinking Expertise. Chicago: The University of Chicago Press, 2007.
 We describe such tools in Chapter 13: Taxonomies of epistemic tools and infrastructures and Chapter 14: Professional epistemic games.