First, the prosecution of the Lincoln conspirators, though nominally based on conspiracy, was not based on conspiracy as an inchoate offense. (78) The whole point of the Lincoln assassination is that the conspirators completed the target crime--the crime to which the conspiracy was directed.
Casebook authors often have a difficult decision to make about where to locate the materials on the conspiracy doctrine because conspiracy does double duty as an inchoate offense and as a mode of liability.
The generally accepted common law definition of a criminal conspiracy is "an agreement between two or more persons to commit an unlawful act or to commit a lawful act by unlawful means." (18) As an inchoate offense, conspiracy permits the government to indict groups of confederates who have not yet committed any crime apart from merely agreeing to break the law at some future time.
If the choice to intend to do something criminal is the core of any inchoate offense, then one might ask: Why criminalize only statements at a stage earlier than Dressler's fifth stage of commencing the commission of the crime?
If the act of intentionally and directly causing a result should not be criminalized, the state cannot be justified in enacting an inchoate offense to prevent persons from merely creating a risk of that result.
(45) Why should we be more tolerant of strict liability when the ultimate harm X is not explicitly mentioned as an element of the inchoate offense? I am unable to think of a case in which our intuitions would favor the result reached by applying their principle rather than mine.