In the classic view of contracts, contractual arrangements work because they provide legal certainty of the precise responsibilities that are assumed by parties. With the act of contractually specifying what is agreed on, parties fixate and communicate their respective positions. However, as modern contract theory recognises, such fixation is only possible to a very limited extent, and actually is not even desired to such an extent by the contract parties themselves. This does not mean that there is no need for legal certainty, only that this is a merely a limited virtue. In modern contract practice parties rather wish to have a certain flexibility to adapt to unforeseeable developments, while still having sufficient guarantees that fair results will be obtained. This means that contractual communication should not solely occur through the contract but rather beside and outside the contract, thereby influencing the contract itself. Hence contracts themselves should become responsive. On the one hand, courts have responded by allowing contractual and pseudo-contractual constructs to create ties between parties that were not explicitly made (connected contracts). On the other hand, in certain areas a reconceptualisation of contract theory is required to allow interacting parties to modulate their positions according to growing insights in their relationship. There are a number of lines of research to be pursued.