Regarding Brother Paul and the opportunity cost the monastery supports for having him in charge of the surveillance of the bridge’s toll. First is important to remind the definition of O.C:

Is the benefit foregone from not using a good or resource in its best alternative use. Therefore if there is no better alternative, there is no Opportunity Cost.

But according to Brother Phillip, this isn’t the case. Clearly, one may infer that part of the O.C we are trying to identify, is compounded by the boost in the granary production, given Brother Paul could apply his experience and that he would develop the task with more joy than a younger Brother with more energy, who at the same time could also dedicate himself to someother diligence -where he could be more productive- such as plowing, etc.  

From the individual -Brother Paul’s- perspective, the calculation of the opportunity cost will be different, given that Labor has a negative direct impact on his utility (generates disutility to him). What he will be comparing then, will be how many hours of work he will contribute, keeping in mind he will always want to work less for more compensation. Moreover, the returns he obtains for working is an indirect impact (Benefit). 

One can’t always trust his intuition.

By Laura M. Gonzalez