This thesis is concerned with the relation between the notion of national language and identity, in particular the manner in which a shared sense of national belonging is expressed and reproduced through the display of public attitudes towards foreign loanwords in society. Employing the case study of contemporary Japan, this research seeks to uncover the process by which a national language is conceived of as a symbol of national identity that requires the exclusion of certain loanwords from the perceptual framework of this national language. To this end, contemporary Japanese discourse on language has been scrutinised, drawing on nationwide newspaper entries published between 1991 and 2010 on the subject of foreign loanwords known as 'gairaigo' in Japanese. Through this analysis, the thesis argues that the fierce debate on the use of loanwords can be understood as a particular manifestation of the ongoing (re-)negotiation of Japanese national identity. On the whole, criticism and praise of the use of loanwords are found to be grounded upon a desire to establish specific understandings of Japaneseness in reference to the otherness symbolised by loanwords. Both parties in the debate are, therefore, highly reliant upon notions of national consciousness, challenging the common view that debates over the use of foreignisms are merely that of an opposition between nationalists who argue for the purity of language and internationalists who argue against such normative boundaries in language. In this context, it is argued that loanwords represent a foreignness, or otherness, felt within a society that constructs an 'internal other', or 'outside within', to a Japanese 'self', the identity of which is neither autonomous nor clearly delineated.

The present research attempts to develop a general model of the diffusion of Western loanwords in contemporary Japanese within the variationist framework. It describes and predicts, based on empirical evidence from apparent- and real-time data, the elaborate process of changes in favor of loanwords as opposed to their existing native equivalents. First, people's self-reporting shows a consistent tendency for a younger generation to show a stronger preference for loanwords than an elder one. This indicates changes in favor of loanwords are in progress in apparent time (Chapter 4). Second, the above-mentioned age gradient is attested to by corpus-based data. It also reveals that the occurrence of loanwords is accounted for multi-dimensionally by a wider range of language-external factors such as generation, education, register and style (Chapter 5). Third, an in-depth study of the individual loanword keesu (< case) reveals that not only external factors but also internal ones, e.g., usage and collocation of the word, have impacts on its occurrence (Chapter 6). Fourth, an investigation of the loanword sapooto (< support) shows that a stylistic variable comes into play in its diffusion in interaction with an educational variable. The loanword is disfavored when the speech setting shifts to formal in particular by the most educated speakers (Chapter 7). Fifth, a real-time approach to loanword adoption verified that individuals can change their language attitude or behavior throughout their lifetime. It highlights importance of longitudinal observation of the phenomenon in making a more accurate prediction of change (Chapter 8). The present research confirms that the occurrence of loan variants is bound by various social and linguistic contexts. The above empirical findings contribute to the field of variationist study by opening up the possibility of analyzing linguistic variation in Japanese at the lexical level.