I was sitting in a workshop a while back (actually, it was a lecture, but nobody calls them ‘lectures’ when staff are attending), and an eminent professor used the phrase ‘cross disciplinary’.

“That’s pretty retro,” I thought. “Everybody talks about being ‘multi-disciplinary’ or ‘inter-disciplinary’. Actually, even that is a bit passé. ‘Trans-disciplinary’ is the word of the day. What the hell do these terms mean, anyway?”

Given that most of my working life consists of writing:

‘Be precise’,
‘What exactly do you mean?’, and
‘Reword for clarity’

in the margin of draft grant applications, I thought that I should come up with some working definitions, at least for my own satisfaction.

After all, these words are fundamental to our conception of modern research. They deserve precise definitions.

Cross disciplinary

So, I turned to the Bible of research definitions, The Proposed Standard Practice for Surveys of Research and Experimental Development (the poor old Frascati manual, doomed never to grow up into a real standard, it would seem). The Organisation for Economic Co-operation and Development (OECD) draw their definition of ‘research’ from the Frascati manual, and many countries draw their definition of research from the OECD, so the Frascati is the source of definition for most major funding agencies.

Unfortunately, Frascati is no help here. Cross disciplinary doesn’t even appear in the latest edition (2002, 6^th edition).

Word.net (my favourite thesaurus) is a bit more helpful. A discipline is a branch of knowledge (‘bailiwick’ is a synonym – who knew!). Cross describes two lines that transverse one another, like this: X. It is a place where things intersect, where they meet and combine, or cut across one another.

Still, Word.net isn’t a real dictionary. If you want a real dictionary, you go to the OED. For me, the venerable Oxford English Dictionary (OED) is the gold standard of word definitions. So, I was surprised to find that it didn’t offer a definition of ‘cross disciplinary’ at all. Go figure! It does helpfully explain that discipline is based on the idea of:

A branch of instruction or education; a department of learning or knowledge; a science or art in its educational aspect.

It comes from the the Old French for instruction of disciples.

So, if your research is cross disciplinary (or ‘cross bailiwick’, perhaps) then you are working at a place where branches of knowledge meet (sometimes in an angry way, because everyone is, you know, a little bit cross).

Interdisciplinary

It turns out that the Frascati Manual is a bit more helpful when it comes to ‘interdisciplinary’ work. It doesn’t define it, but at least it mentions it. Just once, when it classifies fields of science and technology, under ‘other engineering sciences’:

Other engineering sciences (such as chemical, aeronautical and space, mechanical, metallurgical and materials engineering, and their specialised subdivisions; forest products; applied sciences such as geodesy, industrial chemistry, etc.; the science and technology of food production; specialised technologies of interdisciplinary fields, e.g. systems analysis, metallurgy, mining, textile technology and other allied subjects)
– Frascati Manual, 2002, Chapter 3 Institutional Classification in Table 3.2. Fields of science and technology

Word.net comes through for me, though. It defines interdisciplinary as

drawing from, or characterized by, participation of two or more fields of study

The OED also comes through. It defines interdisciplinary in this way:

Of or pertaining to two or more disciplines or branches of learning; contributing to, or benefiting from, two or more disciplines.

Perhaps we can say that interdisciplinary work draws upon, and gives back to, multiple fields of learning. Whereas ‘cross disciplinary’ work happens where they intersect, interdisciplinary work reaches into multiple areas, grabs what it needs, brings them together and then feeds them back to those areas. Maybe…

Multidisciplinary

Frascati refers to multidisciplinary when it discusses dividing science and technology research up by function.

Where appropriate, e.g. in the case of projects with a multidisciplinary character, a breakdown of resources by several fields of science and technology should be made.
– Frascati Manual, 2002, 4.4. Fields of science and technology in 4.4.3. The criteria for distribution

In the section where it describes collecting information on biotechnology research, it explicitly describes biotechnology as “a multidisciplinary field”. This may come as a surprise to some biotechnologists:

This poses particular problems in categorising biotechnology for survey purposes. The current OECD definition of biotechnology is preliminary and has mainly been piloted in R&D surveys of the business enterprise sector. For comparability, the definition is also recommended for use in other sectors. The experience gained from using the definition in all sectors will lead to further revisions of the current definition.
– Frascati Manual, 2002, Biotechnology-related R&D in Annex 4 R&D Related to Health, Information and Communication Technology (ICT) and Biotechnology

Unfortunately for my purposes, it doesn’t actually provide a definition for multidisciplinary, so we are just feeling around the edges here. I do find it interesting that both interdisciplinary and multidisciplinary appear in the one volume, though. I suspect that chapter 3 was written by a different person to chapter 4 and the editor didn’t pick up that two different terms had been used.

Word.net isn’t much help. It doesn’t provide a definition for multidisciplinary or even for multi-. I love Word.net (and, in its defence, it isn’t a dictionary as such), but I’m not feeling the love today.

The OED gives us a straightforward definition. Multidisciplinary is defined as

Combining or involving several separate academic disciplines.

Maybe we can say that cross disciplinary work happens at the intersection of disciplines, interdisciplinary work draws on multiple disciplines, and multidisciplinary work combines different disciplines. Then again, maybe I’m reaching for something that isn’t there.

Transdisciplinary

Frascati strikes out with transdisciplinary. There is a lot of discussion of transmission and translation, but nothing about transdisciplinary. I guess that isn’t a surprise, as Word.net and the OED are no help either.

Casting the net a bit wider, Google’s ‘define’ feature provides a definition from Wikipedia. When you dig into it though, Wikipedia (at the time of writing) is in a bit of a mess in this area. Transdisciplinary redirects to “Interdisciplinarity,” while transdisciplinarity has its own article. [Note to self: redirect Transdisciplinary to Transdisciplinarity.]

So, back to first principles. The OED helpfully tells us that trans- comes from the Latin preposition when means ‘across, to or on the farther side of, beyond, over’. It then provides a number of meanings, all of which relate to, or enlarge on, this origin.

• With the sense ‘across, through, over, to or on the other side of, beyond, outside of, from one place, person, thing, or state to another’ (e.g. transcribe);
• With the sense ‘beyond, surpassing, transcending’, (e.g. transhuman).

Then it lists specialised usages in geography, chemistry, genetics, biochemistry and physics.

Perhaps we can say that transdisciplinary work seeks to move beyond a particular discipline (or multiple disciplines) to something on the other side. Do disciplines have sides? I know they sometimes take sides (and defend their side vigorously), but do they have a shape or a geography that can be travelled through? Are there border crossings, and where do you arrive when you get there?

Where does all this get us?

• Cross – At the intersection of disciplines.
• Inter – Drawing from or relating to more than one discipline.
• Multi – Combining different disciplines.
• Trans – Who knows? Going beyond a discipline, perhaps.

Or maybe there is a much, much simpler explanation. Perhaps it is just fashion. The eminent professor that I was listening to was about to retire. He grew into a different vocabulary than people undertaking PhDs now. Each term has limits, and those limits annoy people. They don’t want to be constrained by the ‘old’ term. So they move on. They create their own territory. This is fine.

The thing that worries me is the number of people I meet who use one or other of these terms to describe their work. Is there anyone left who is working inside a discipline, at the core? Or is everybody mixing it up, trying to move beyond their own discipline, into something new? Where do you sit?