could then revoke without any remedy for the promisee. The promisor had maximum protection and the promisee had maximum risk in this scenario. The modern view of how option contracts apply now provides some security to the promisee in the above scenario. Essentially, once a promisee begins performance, an option contract is implicitly created between the promisor and the promisee. The promisor impliedly promises not to revoke the offer and the promisee impliedly promises to furnish complete performance, but as the name suggests, the promisee still retains the "option" of not completing performance. The consideration for this option contract is discussed in comment d of the above cited section. Basically, the consideration is provided by the promisee's beginning of performance. Case law differs from jurisdiction to jurisdiction, but an option contract can either be implicitly created instantaneously at the beginning of performance (the Restatement view) or after some "substantial performance". Cook v. Coldwell Banker/Frank Laiben Realty Co., 967 S.W.2d 654 (Mo. App. 1998). It has been hypothesized that option contracts could help allow free market roads to be constructed without resorting to eminent domain, as the road company could make option contracts with many landowners, and eventually consummate the purchase of parcels comprising the contiguous route needed to build the road. Assignability It is a general principle of contract law that an offer cannot be assigned by the recipient of the offer to another party. However, an option contract can be sold (unless it provides otherwise), allowing the buyer of the option to step into the shoes of the original offeree and accept the offer to which the option pertains. Contract theory In economics, option contracts play an important role in the field of contract theory. In particular, Oliver Hart (1995, p. 90) has shown that option contracts can mitigate the hold-up problem (an underinvestment problem that occurs when the exact level of investment cannot be contractually specified). However, there is a debate in contract theory whether option contracts are still useful when the contractual parties cannot rule out future renegotiations. As has been pointed out by Tirole (1999), this debate is at the center of the discussions about the foundations of the incomplete contracts theory. In a laboratory experiment, Hoppe and Schmitz (2011) have confirmed that non-renegotiable option contracts can indeed solve the hold-up problem. Moreover, it turns out that option contracts are still useful even when renegotiation cannot