This chapter discusses and contrasts the manner in which the notion of indeterminacy is theorised in contemporary sociolinguistics and integrational linguistics. Linguistics provides an essential source of determinacy in data description and analysis which enables sociolinguistics to maintain its historical disciplinary identity as a positivist-empirical form of enquiry. Forms of linguistic enquiry with such an a priori methodological commitment cannot in practice afford to countenance the integrationist principle of the radical indeterminacy of the linguistic sign. Contemporary sociolinguistics is therefore in the curious and ultimately incoherent position of denying the fundamental postulate of linguistics while simultaneously lauding its ability to provide authoritative analyses of linguistic data. The most explicit account of the role played by the notion of indeterminacy in contemporary sociolinguistic theory can be found in A. M. Jaffe. Indeterminacy, claims Jaffe, is both a 'fundamental property of social life' and a 'fundamental principle of sociolinguistic variables'.