Computational Creativity: The Final Frontier? Simon Colton1 and Geraint A. Wiggins2 Abstract. Notions relating to computational systems exhibiting cre- to human programmers, users and audiences instead of software and ative behaviours have been explored since the very early days of hardware. It seems that people allow their beliefs that machines can’t computer science, and the field of Computational Creativity research possibly be creative to bias their judgement on such issues [32, 45]. has formed in the last dozen years to scientifically explore the po- Also related to evaluation, our working definition has two con- tential of such systems. We describe this field via a working defi- spicuous and deliberate absences. First, it makes no mention of the nition; a brief history of seminal work; an exploration of the main value of the artefacts and ideas produced. This is because – while it issues, technologies and ideas; and a look towards future directions. is implicitly assumed that we would like our research to lead to the As a society, we are jealous of our creativity: creative people and production of novel and valuable material – the computational sys- their contributions to cultural progression are highly valued. More- tems producing that material may also innovate at aesthetic levels by over, creative behaviour in people draws on a full set of intelligent inventing, justifying and utilising measures of value. Therefore, we abilities, so simulating such behaviour represents a serious technical propose to talk of the impact [20] of creative acts and their results, challenge for Artificial Intelligence research. As such, we believe it rather than the value of the output they produce, and the introduction is fair to characterise Computational Creativity as a frontier for AI of specific value requirements might limit the scope of future Com- research beyond all others—maybe, even, the final frontier. putational Creativity research. Second, while it is popular in Compu- tational Creativity – as it is in AI in general – to apply quasi-Turing- 1 BOLDLY ONGOING tests, comparing generated results with those made by people, our definition does not rule out situations where systems are deemed to Computational Creativity is a subfield of Artificial Intelligence (AI) be creative even though they behave in wholly different ways, and research – much overlapping cognitive science and other areas – to different ends, from people. Notwithstanding the fact that many where we build and work with computational systems that create Computational Creativity researchers use simulations of human cre- artefacts and ideas. These systems are usually, but not exclusively, ative acts to further study humanity, we maintain that one of the real applied in domains historically associated with creative people, such potentials of computational systems is to create in new, unforeseen as mathematics and science, poetry and story telling, musical com- modalities that would be difficult or impossible for people. position and performance, video game, architectural, industrial and For a long period in the history of AI, creativity was not seri- graphic design, the visual, and even the culinary, arts. Our working ously considered as part of the field: indeed, when Margaret Boden definition of Computational Creativity research is: included a chapter on creativity in her book, Artificial Intelligence and Natural Man [3], some observers suggested that it was out of The philosophy, science and engineering of computational sys- place [4]. This may have been for good reason! We consider through- tems which, by taking on particular responsibilities, exhibit be- out this paper the difficulties that beset the study of Computational haviours that unbiased observers would deem to be creative. Creativity; there was a lot to be said for postponing such a difficult This definition contains two carefully considered subtleties. subfield until the larger area is better understood – as it now is. But Firstly, the word responsibilities highlights the difference between perhaps this is also symptomatic of scepticism: perhaps creativity is, the systems we build and creativity support tools studied in the HCI for some proponents of AI, the place that one cannot go, as intelli- community [53] and embedded in tools such as Adobe’s Photoshop, gence is for AI’s opponents. After all, creativity is one of the things to which most observers would probably not attribute creative intent that makes us human; we value it greatly, and we guard it jealously. or behaviour. A creative responsibility assigned to a computational From the beginning of the modern computing era, notable experts system might be: development and/or employment of aesthetic mea- have questioned the possibilities of machine intelligence with refer- sures to assess the value of artefacts it produces; invention of novel ence to creative acts. For example, the celebrated early neuroscientist processes for generating new material; or derivation of motivations, Sir Geoffrey Jefferson wrote: justifications and commentaries with which to frame their output. Our second subtlety is in the methodological requirements for “Not until a machine can write a sonnet or compose a concerto evaluation. We emphasise the involvement of unbiased observers because of thoughts and emotions felt, and not by the chance in fairly judging the behaviours exhibited by our systems, because, it fall of symbols, could we agree that machine equals brain” seems, there is a natural predilection for people to attribute creativity Geoffery Jefferson [38] 1 Reader in Computational Creativity, Computational Creativity Group, This was in response to Turing, who replied that Jefferson was Department of Computing, Imperial College, London, UK. merely expressing “The Argument from Consciousness” against in- ccg.doc.ic.ac.uk, [email protected] 2 Professor of Computational Creativity, Centre for Digital Music, School of telligent machines, before going on to demolish it as solipsism [56]. Electronic Engineering and Computer Science, Queen Mary, University of Other AI pioneers saw the possibilities for the study and simulation London, UK. [email protected] of creativity with computers. Claude Shannon was among them: “Shannon wants to feed not just data to a Brain3, but cultural challenge existing AI techniques, leading us (and others) to propose things! He wants to play music to it!” Alan Turing [36, p. 251] improvements. For instance, the HR mathematical discovery system [13] has improved constraint solving over algebraic completion prob- In the three decades following such early interest, there were a few lems [9]. In addition, our projects often lead to test suites and canoni- particularly successful attempts to build creative systems, though not cal problems for AI techniques; e.g., HR has contributed to the TPTP always reported in AI outlets. For example, artist Harold Cohen ex- library of problems for automated theorem provers [25]. hibited and sold paintings created by his AARON robot [43] in tradi- The Painting Fool project (www.thepaintingfool.com) concen- tional art circles. Kemal Ebcioglu’sˇ CHORAL system [31] could pro- trates on automating physical, but more importantly cognitive, as- duce chorale harmonisations that are reliably distinguishable from pects of painting, and shows how extant AI techniques can be those of J. S. Bach only by experts (and then often because they are pipelined to increase the creative responsibility of systems. The too quirkily Bach-like). But during this period, these attempts were Painting Fool creates and paints scenes using: (a) constraint solv- isolated, and lacked unifying theory and methodology. The first at- ing to place structural elements [17] that are themselves gen- tempt of which we are aware to provide a theoretical framework for erated by context free grammars via the ContextFree system the study of creativity in AI is that of Margaret Boden [2], which (www.contextfreeart.org) [24]; (b) machine learning to predict when continues to have philosophical impact in Computational Creativity. two abstract images have too much structural similarity [19]; (c) var- There isn’t space here for a survey of the field, so we draw more on ious evolutionary methods to generate abstract art pieces [21] and our own work than on others’; we apologise to those whose research image filters [26], and (d) concept formation via HR for the inven- we omit. More background on the development of Computational tion of fitness functions for scene generation [15]. An image created Creativity, especially in the main academic events, is available in the by the system is shown in Figure 1a [24]. AI Magazine [8]. In the next section, we describe how research is Application (d) above captures the notion of handing over creative progressing in terms of our first point above – the devolution of cre- responsibility. A simple evolutionary approach was used to position ative responsibility from human to machine – with implementations and order hundreds of rectangle placeholders, producing scenes sim- that create and assess artefacts of their own. It is a picture of a small ilar to that of downtown Manhattan (as seen from the Staten Island but buoyant field, developing methods, methodology and real tools ferry) [15]. The fitness function was hand-crafted, involving positive for creative production. Thereafter, in section 3, we focus on evalua- and negative correlations between size, shape, colour and location of tion and the development of relevant methodology, which is particu- the rectangles. Then, in order to hand over more creative responsibil- larly problematic in an area where it is often hard to say a priori what ity, HR was given the background concepts that constituted the hand- one is even trying to achieve. In the final section, we speculate on crafted fitness function, and asked to invent new mathematical func- possibilities for the future of Computational Creativity research. tions involving correlations which could be themselves interpreted as fitness functions. For each of ten generated fitness functions, a highly 2 WHERE NO PROGRAM HAS GONE BEFORE fit cityscape scene was evolved.