38 3 TheFoundations of Human-Experiential Design Tomiyama (2009) pointed out that “scientific understanding helps researchers to identify what to research, and helps design practitioners to correctly understand what can be done and what cannot with a particular type of design methodology” (p. 50). Table 3.1 suggests that ‘design knowledge’ could be externalized and could be a matteroftheintellect,butcan‘design’beconceptuallyexplainedthroughlanguage? Asfaras‘design’addressesallthenaturaldimensionsofourexperiences,including our sensual perception, it is not easy to externalize. So ‘design’ is not merely a matter of language, nor just a matter of the intellect. Here, a question arises: What is scientific knowledge in design research actually? Jurgen Habermas (1998, 33) discussed a distinction between know-how and know-that. A person with habituated skills has ‘know-how’ which is the under- standing in which a skilled practitioner crafts or executes something. On the other hand, ‘know-that’ is the explicit forms of knowledge in which a person is able to know-how. A number of design activities can be seen as ‘know-how’ based, originating from a craft-work perspective and therefore difficult to express in the explicit formsoflanguage,andthusnotadequatelycoveredbytoday’sfastevolving and complicated design process accounts (Poggenpohl 2009; Krippendorff 1995; Owen1998;Buchanan2001). Humanshavebothembodiedandabstractformsofknowledge.Theyaffecteach other, and are not easily dissociable. In scientific research, researchers and scholars mainly deal with descriptive knowledge with an explicit form of language. On the other hand, humans also have unexpressed knowledge, so-called tacit or implicit knowledge(Polanyi1966).Ingeneral,implicitknowledgecanbecommunicatedby shared meaning between people. Effectiveengagementbetweenexplicitandimplicitknowledgecouldinprinciple enhance creativity in the design process and open up a new research area in design disciplines. Practitioners in business and design management have tried to adopt the term tacit knowledge to describe inexpressible mechanisms of individual and organizational creativity. However, the approach has not been successful (Nonaka 1991).Onereasonis thatthereis a lack of understandingof the notion of creativity. Ironically, creativity itself is hard to illustrate and externalize. If the context of design activity is preceded with inexpressible knowledge, creativity is also equal to, or part of, tacit knowledge. Inreality,designerpractitionersgenerallyignoretheresultsofdesignresearchon the assumption that design research is inapplicable and useless to design practice. Hence,designersexecutetheir own design process without explicitly using theories and methodologies. Designers will claim that design solutions that come from scientific theories and methods are relatively frail compared with design solutions obtained on the basis of intuition (Tomiyama 2009). In other words, even though design can be improved by scientific studies addressing, for example, accessibility, usability, or acceptability, it is not considered by designers to be suitable for aesthetic and sensitive design in practice. Certainly, there is something not easy to externalize in design knowledge (and not only design knowledge but also human knowledge in general). But, designers