There are other views that deviate from the above standard definitions of possibilism. Carlson (1995: 99–109; 1999) defends a view that bears resemblance to possibilism in which the sole obligatory act-set is a unique minimally specific invariably optimal act-set. At t an act-set is optimal for an agent S just in case its outcome is at least as good as any other act-set that is performable for S at t. An invariably optimal act-set is one which is optimal no matter what S does at t. An invariably