Строй современного английского языка

Invariable Meaning 189
I n proceeding now to consider different arguments referring to the nine questions enumerated here, we will first of all point out the problem of various structural meanings inherent in a grammatical form and of an invariable meaning, that is, one to be found in every possible single application of a form. This has been treated in different ways with reference to such questions as the general meaning of a case, for instance of the genitive case in Russian or Latin, etc.
Whether we think it necessary to find an invariable structural meaning which manifests itself in different ways in different applications of a grammatical category, or whether we deny the necessity of such an invariable meaning, is a matter which largely depends on a scholar's theoretical views on the meaning of grammatical categories and grammatical forms in general. We can hardly expect either of these views (for or against an invariable structural meaning for every category and every form) to be definitely proved as the only right one. We will assume that an invariable meaning does exist, and then try to find out what it is in every case.
Starting, then, with the question of polysemy or homonymy of forms like knew or lived, which may either denote a real action in the past, or an unreal supposition in the present or future, we may look for an invariable meaning comprising both these concrete applications. This meaning would seem to be something like "an action not actually happening in the present", or an action removed from present reality, that is, either having occurred in the past and in this way cut off from present reality or else only vaguely supposed, or even definitely unreal, and in this second way cut off from present reality.¹ This would justify the view that knew or lived in all its applications is one and the same form, which we may call past indicative, and which is used in certain syntactical contexts to denote an unreal action in the present or future.
While this way of interpreting facts will probably never be proved to be the only correct one, -there are many arguments in its favour and we will here endorse this view of forms like knew and lived.
If that is accepted, a similar reasoning will hold good concern? ing the forms had known and had lived. The common element of meaning, that is the invariable to be found both in the sentence I had known this before and in the sentence If I had known this 1 should have come may be defined as follows: an action not really
¹ This idea was propounded, in a somewhat different context, by Prof. A. Potebnia with reference to some facts of Slavonic languages; e.g. in Russian the form of the conditional mood сказал бы is a combination of the past tense form сказал with the particle бы, which itself is by origin a past tense form of the verb быть.

140 The Verb: Polysemantic and Homonymous Forms
h appening at a given period in the past; the two applications of that common invariable would then result in the following meaning: (a) an action happening before that period of the past which is being considered, and (b) an action merely supposed, and not actually happening in the past. The additional difficulty in this second item is, that everything has to be treated as belonging to the past (in some way or other), whereas with the first item the distinction was between the past and the present.
This approach to things is also possible in the case of our item (3), where the forms in question are, should come and would come, respectively. In trying to arrive at an invariable meaning for these forms, we will look for something which might establish a connection between an action unreal in the present and an action expected to happen at some moment future from the point of view of past time. The invariable in this case may be defined something like this: an action not really happening either in the present or in the specified period of the past; that idea is then substantiated either

1. 
   as something merely supposed for the present or future, or
   
2. 
   as an action viewed from a past viewpoint as happening in the future.
   

A similar reasoning would of course have to be applied to forms like should have come and would have come, with everything shifted, as it were, one step further back into the past: the invariable in this case would be something like "an action not actually happening either in the past, present, or future", and the applications would be, (a) an unreal action in the past, and (b) an action viewed from a past viewpoint as completed at a certain time in the future. In this last type of forms the past dominates throughout.
Similar considerations will hold good with reference to forms like should be coming, would be coming, should have been coming, would have been coming, which, however, are rarely found in their temporal application (future-continuous-in-the-past, future-perfect-continuous-in-the-past). Everything stated so far would also apply to the corresponding forms of the passive voice, wherever a verb admits of passive forms at all.
The next item, which we gave under number 5, is of a somewhat different character, and presents us with new difficulties. Besides being used to denote an unreal action in the present, and an action expected in the future from a past viewpoint, the phrase would come (in this particular case the verb would is completely dissociated from the verb should) can also express a repeated action in the past. For this problem, there seems to be no convincing way of finding an invariable meaning able to cover both the meaning of unreality in the present and expectation in the future from a past viewpoint. So, unless and until such common ground for an invariable is found, it will be well to say that would come denoting un-