The "psychological", or "mentalistic" view of the phoneme was brought back into favour by generative phonology, and the idea of the phoneme as a "target" has recently been revived, albeit under different terminology by M. Tatham (77).
It is definitely not possible to establish such ideal sounds which do not exist in reality. For this reason the American linguist L. Bloomfield (46) and his followers rejected the view and the English phonetician D. Jones (64), while basically favourable to the view preferred in practice to take a "physical" view. This approach to the phoneme as a clearly idealistic one cannot be taken up by Soviet linguists.
The so-called "functional" view regards the phoneme as the minimal sound unit by which meanings may be differentiated without much regard to actually pronounced speech sounds. Meaning differentiation is taken to be a defining chaiacteristic of phonemes. Thusthe absence of palatalization in [?] and palatalization of [?] in English do not differentiate meanings, and therefore [?] and [?] cannot be assigned to different phonemes but both form allophones of the phoneme [?]. The same articulatory features of the Russian [л] and [л/] do differentiate meanings, and hence [л] and [л'] must be assigned to different phonemes in Russian, cf. мол - моль, лог - лёг. According to this conception the phoneme is not a family of sounds, since in eveiy sound only a certain number of the articulatory features, that is those which form the invariant of the phoneme, are involved in the differentiation of meanings. It is the so-called distinctive features of the sound which make up the phoneme corresponding to it. For example, every sound of the English word ladder includes the phonetic feature of lenisness but this feature is distinctive only in the third sound [d], its absence here would give rise to a different word latter, whereas if any other sound becomes fortis the result is merely a peculiar version of ladder. The distinctive-ness of such a feature thus depends on the contrast between it and other possible features belonging to the same set, that is the state of the vocal cords. Thus when the above-mentioned features are distinctive, lenisness contrasts with fortisness. Some approaches have taken these oppositions as the basic elements of phonological structure rather than the phonemes in the way the phoneme was defined above. The functional approach extracts non-distinctive features from the phonemes thus divorcing the phoneme from actually pronounced speech sounds. This view is shared by many foreign linguists: see in particular the works of N. Trubetskoy (34), L. Bloomfield (46), R. Jakobson (62), M. Halle (62).
The functional view of the phoneme gave rise to a branch of linguistics called "phonology" or "phonemics" which is concerned with relationships between contrasting sounds in a language. Its special interest lies in establishing the system of distinctive features of the language concerned. Phonetics is limited in this case with the precise description of acoustic and physiological aspects of physical sounds without any concern to their linguistic function. The supporters of this conception even recommend to extract phonetics from linguistic disciplines which certainly cannot be accepted by Soviet phoneticians.
A stronger form of the "functional" approach is advocated in the so-called "abstract" view of the phoneme, which regards phonemes as essentially independent of the acoustic and physiological properties associated with them, that is of speech sounds. This view of the phoneme was pioneered by L. Hjelmslev and his associates in the Copenhagen Linguistic Circle, H.J. Uldall and K. Togby.
The views of the phoneme discussed above can be qualified as idealistic since all of them regard the phoneme as an abstract conception existing in the mind but not in the reality, that is in human speech, speech sounds being only phonetic manifestations of these conceptions.
The "physical" view regards the phoneme as a "family" of related sounds satisfying certain conditions, notably:
1. The various members of the '"family" must show phonetic similarity to one another, in other words be related in character.
2. No member of the "family" may occur in the same phonetic context as any other.
The extreme form of the "physical" conception as propounded by D. Jones (64) and shared by B. Bloch and J. Trager (45) excludes all reference to non-articulatory criteria in the grouping of sounds into phonemes. And yet it is not easy to see how sounds could be assigned to the same phoneme on any other grounds than that substitution of one sound for the other does not give rise to different words and different meaning. This approach may seem to be vulgarly materialist since it views the phoneme as a group of articulatorily similar sounds without any regard to its functional and abstract aspects.
Summarizing we may state that the materialistic conception of the phoneme first put forward by L.V. Shcherba may be regarded as the most suitable for the purpose of teaching.