"English” here means a 4-year-course of study at a full university, be it for the purpose of training for a grammar school teacher or some other course of study, such as MA or comparable. I'm taking the issue to be what the place and the significance of the teaching of diachronic English linguistics in such a curriculum is (and not research by scholars). Also I will adopt without further ado the traditional definition of "anglistics” of comprising "American”, "Canadian” etc studies, and of "English” as the unmarked term for all regional and social varieties of English.
The question of the place of historical linguistics in an English curriculum cannot be seen in isolation : to me it is to be seen as part of the larger question of what the place of linguistics is vs literature. There seem to be two models: the European and the American one. The latter is often characterized by a little linguistics often appendicital to literature, and mostly reflected in the fact that there may be one linguist (often "stylistician”) in the English department, or none at all, the study of English being the study of literature written in English. Whether or not this is to be related to the fact that the American situation is a native speaker situation and the absent L2-acquisition motivation is not a point of discussion here. The situation in England is a non-native situation too, and it is quite different.
The question of the role of historical linguistics is embedded in and part of a wider problem in the area of the coherence of the field of anglistics: there are two major splits in the field total that have resulted in the lack of coherence and the lack of identity and, concomitantly, of philosophy, of the field of anglistics. The first split is along the lines of literature and linguistics, reflecting a misguided idea based on a version of structuralism that both types of texts are distinct (cf. Pratt). This has led to an institutional split in terms of departmental organization and into terms of different people doing different things in an incommunicable way. The second split - within linguistics - is between synchronic and historical linguistics, due to another misunderstanding of or misreading of (cf. Coseriu!) a version of structuralism. This two-way split has prevented the development of a coherent identity and philosophy of the field of anglistics, and has ultimately led to ESSE having to have a workshop on the topic for a fresh start to do the field's philosophical homework.
The negative impact of this split is the effect this has on the intellectual attractiveness of anglistics. The lack of communicability between the subfields means that two essential functions of any modern humanities-based studies cannot be accessed: interdisciplinarity and the benefits of alterity. An a-historical course, or a course divorced from the neighbouring fields would mean that essential links cannot be drawn from history to social history to linguistic history. This sort of link will enable -from a didactic point of view - a depth of knowledge processing and knowledge integration that a compartmentalised or deficient (without the historical linguistics aspect) course could never achieve.
As to alterity, any modern culture-based course of study must make the insights provided by alterity a central intellectual concern. This is where the place of historical linguistics is finds an essential part of its motivation. Cultural identity is to a large part relationally defined, i.e. in terms of contrast to "others”. Essentially, otherness resides in history. Modern identity - and crucially also linguistically given identity - is defined in terms of one's difference from the past, thereby broadening the range of possibilities and possible identites, which could have existed and which in fact have existed. This kind of definition by contrast with earlier given potentialities is achieved by literature as much as it is achieved by - historical - linguistics,- if that linguistics is seen basically as one developmental line, as a set of potential and partially realised lines of development. The linguistic side will not be able to achieve this goal if it is a linguistics that is built on a discrete and uncommunicable line between two different types of linguistics, and between linguistics and literature. Needless to say that this defines a certain requirement for the competence of university teachers, and for the institutional organisation of the field (do we really want two different professors for synchronic and diachronic linguistics?).
This being ESSE, I have the European model in mind, with a traditional cohabitation of linguistics and literature. Within this framework, the function of histling in a curriculum of studying "English” is also a function of the question of the unity of "English” as an institutionalized university subject/curriculum. If there is linguistics, it must undoubtedly be historical linguistics too, since the study of literature does not make sense without historical literature. I assume that the study of literature includes the study of "older” texts, i.e. is also historical literature (any literary text is historical the moment it has been penned).
There are two basic types of motivations/reasons inherent in anglistics itself why historical linguistics must be part of an English curriculum at equal rights:
2.1 Autonomous ones: studying "English” is study the language as a system, and as a system of uses. Studying it in a scientific way means "explaining” it. There are two basic ways of explaining: subsuming data under a (synchronic) principle and telling a story about it. The latter - the evolutionary type - must be at least as much part of a curriculum as the other principle.
There are a number of reasons why knowledge of how things evolved is paramount. To cite only two:
2.2 Another criterion derives from the above-postulated unity of anglistics. The cohabitation of linguistics with literature in a curriculum deserving of the name of anglistics contributes another important motivation for the prominent place of historical English linguistics. Since literature and its study is always historical, it followeth that linguistics too must be historical. Notice that (historical) linguistics is not and cannot be defined as tributary to the study of literature (the "stylistics” person in the US). Essentially, literature is the study of the semiotic mechanims of a specific type of text. The job of linguistics is to make explicit the mechanisms of meaning involved. This applies to more modern literature in the same way as to historical texts, e.g . Shakespeare. For historical texts, the study of the state of the linguistic system is essential in order for us to know whether a form is just normal or foregrounded, or "poetic”. Historical linguistics is about the archeology of the "horizon”, of the linguistic basis for the reconstruction of meanings: how can we know whether a use of "th” in the Shakespeare corpus is poetic or not, if not by analysing the state of the grammar of the language in that particular subcompartment.
It is clear that only such a (historical) linguistics makes sense that is congenial to literature, i.e. is semantic - not formal - in orientation.
It is suggested that there should European minimal requirements for a course in "English”, such that historical linguistics should constitute a quarter of the teaching of the literature/linguistics side (literature 50% and synchronic linguistics the other quarter). To the extent that historical linguistics is NOT an area of specialization, a level of basic knowledge should defined in terms of actual content (e.g. periodization criteria) and possibly of three books (Bolton, BBC history, Baugh/Cable).
Finally, there is a danger that surfaces in many curricula all over Europe: scholars being scholars, and researchers with the career need to publish "modern” research, and in the face of the doctrine of unity of of the subject, it is clear that there must something like a canon of knowledge, typefied by the above references. What must not happen is that scholars carry over their research specialisations into specialisations in teaching. Given the present drive for universities to define "profiles” ( = specialisations) the danger must not be overrated that these profiles will also translate into specialisations in curricula.