"Although presented as being derived from the past, principles in contract law have been subject to constant reformulation, thereby facilitating legal change while simultaneously seeming to preclude it. Principle and policy have been mutually interdependent, propositions not usually being called principles unless they have been perceived to lead to just results in particular cases, and as likely to produce results in future cases that accord with common sense, commercial convenience and sound public policy. The influence of policy has been frequent in contract law, but Stephen Waddams argues that an unmediated appeal to non-legal sources of policy has been constrained by the need to formulate generalised propositions recognised as legal principles. This interrelation of principle and policy has played an important role in enabling an uncodified system to hold a middle course between a rigid formalism on the one hand and an unconstrained instrumentalism on the other"--

"Introduction: empire of reason, or republic of common sense? '[I]f LAW be a science, said Sir William Jones in 1781, 'and really deserve so sublime a name, it must be founded on principle, and claim an exalted rank in the empire of reason'.1 In Goodisson v. Nunn (1792), Lord Kenyon, in dealing with the then very controversial question of when contractual covenants were to be considered independent of each other, was faced with old cases apparently requiring a result that he thought was unjust. He was able to find that the old cases had impliedly been overruled by more recent cases: The old cases... have been accurately stated, but the determinations in them outrage common sense... I am glad to find that the old cases have been over-ruled; and that we are now warranted by precedent as well as by principle to say this action cannot be maintained.2 These two statements, eleven years apart, invite comparison. Both appeal to 'principle', but the word is used with different connotations. Jones spoke of principle as an essential component of the claim of the law - a claim of which Jones evidently approved - to be a rational science. There is no explicit place in this concept for individual judgment on the part of judges or of writers of what legal rules would, on general considerations, be beneficial or desirable in the interests of justice to the parties to a particular dispute or in the interests of society at large in the future. Lord Kenyon, on the other hand, though he also concludes his statement with an appeal to 'principle', was evidently motivated by a desire to avoid injustice to the defendant in the particular case, and to establish a rule that Jones, An Essay on the Law of Bailments, 123 (emphasis in original)"--