It is to be noted that the question in a case such as the present is expressed in terms of the intention of the parties to make a concluded bargain: see, eg, Masters v Cameron (at 360). That is not the same as, although in a given case it may be closely related to, the question whether the parties have reached agreement upon such terms as are, in the circumstances, legally necessary to constitute a contract. To say that parties to negotiations have agreed upon sufficient matters to produce the consequence that, perhaps by reference to implied terms or by resort to considerations of reasonableness, a court will treat their consensus as sufficiently comprehensive to be legally binding, is not the same thing as to say that a court will decide that they intended to make a concluded bargain. Nevertheless, in the ordinary case, as a matter of fact and commonsense, other things being equal, the more numerous and significant the areas in respect of which the parties have failed to reach agreement, the slower a court will be to conclude that they had the requisite contractual intention.
Reference has earlier been made to 'intention'. Cases which typically give rise to problems of the kind presently under consideration are cases in which there is no doubt that the parties had a common intention that at some stage, and by some means, they would enter into contractual relations. They have entered into negotiations for that specific purpose. The problem which arises is that they have exchanged communications which, on the one hand, use the language of agreement but, on the other hand, disclose an expectation that at some future time a document embodying the terms of their contractual arrangement will be brought into existence. Where, as in the present case, the communications which the parties have exchanged are in writing, the question of their 'intention' is, prima facie, to be resolved objectively, and as a matter of construction of the relevant documents.
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This is not a case in which the parties have signed a single document which, because it contains some such expression as 'subject to contract', gives rise to the problem in question. In such a case, the outcome of which will ordinarily turn upon the construction of the single document referred to, questions may arise as to the admissibility of extrinsic evidence in aid of the construction of the document: see Air Great Lakes Pty Ltd v K S Easter(Holdings) Pty Ltd (1985) 2 NSWLR 309 per Hope JA. The case involves the objective determination of the intention of the parties from a consideration of a series of communications exchanged by them in the context of their dealings over a period of time. In those circumstances it is both appropriate and necessary to have regard to the commercial circumstances surrounding the exchange of communications and, in particular to the subject matter of those communications: Allen v Carbone [1975] HCA 14; (1975) 132 CLR 528 at 531-532. Furthermore, as was noted earlier, it is proper to have regard to communications between the parties subsequent to the date of the alleged contract to the extent to which those communications throw light upon the meaning of the language which is being considered for the purpose of determining whether it expresses an intention one way or the other upon the critical matter. At the least, such subsequent communications will often form part of the context in which the particular exchanges in question are to be evaluated (548 550).