Actually, he can force you to sell. Or more correctly, a court can. Your partner could file for something called "partition". This is a legal remedy available to co-owners of property when they cannot agree as to ownership matters. It provides for the division of property. Accordingly, if a property can be physically divided the court will so instruct (and raw land may well qualify depending on zoning requirements); if division would be impracticable (as in the instance of a single family house, etc,) a court would order a sale in lieu of partition and the proceeds would be equitably divided among the co-owners. However, before doing so, the court would permit one co-owner to purchase the interest of the remaining co-owner at fair market value.At this point you should consult with a local real estate attorney as to your specific rights in this case.