Free will acts as a distinguishing factor along a thin line that divides humans and animals. The attributing factors that lend humans, more specifically a person, the essential difference can be found in the structure of their wills. However, free will is much more complex than one would think, as is soon discovered when considering free will in terms of incriminating a defendant or other cases in which a distinction is made between free will of desires and free will of actions. Harry G. Frankfurt outlines through his hierarchical model of will the capacity for self-evaluation and “the notion of an effective desire-one that moves a person all the way to action”, thus illuminating a slightly problematic view of 1st order and 2nd order desires
