What role did Stalin play in the instigation and carrying out of the Great Purge in the Soviet Union?I have been learning about this in class and...

Stalin was probably the ultimate evil genius in that he
created a bureaucracy that allowed him to exercise absolute power over millions of
people while at the same time removing himself from any overt responsibility for its
brutal excesses.  The hierarchy of the Soviet secret police--from the Cheka to OGPU and
NKVD and KGB--made it possible for Stalin to ascribe blame for the incredible massacres
(that were an essential part of his dictatorial policy) to apparatchiks like
Dzherzinsky, Yagoda, Yezhov, and Beria.  Even when Khrushchev attempted to
"de-Stalinize" in the late 1950s, the popular description of the Great Purges was the
Yezhovshchina or Yezhov Era, which made it seem as though Stalin's lieutenant (his
"dwarf") was operating on his own without any instruction from the Party
Secretary.

Stalin's obvious paranoia--his grim
determination to rid himself of anyone and everyone who might even potentially pose a
threat to his power--revealed itself most obviously in the show trials of the late 1930s
prosecuted by Vyshinsky that led to the deaths of so many of the original cadre of
Bolsheviks such as Kamenev, Zinoviev, and Bukharin.  However, the Purges may be seen to
have started with the assassination of Sergei Kirov on December 1, 1934, an act that was
clearly motivated by the man's enormous popularity--which naturally was interpreted by
Stalin as a threat to himself.  The man who pulled the trigger implicated Nikolai
Bukharin before being executed, a transparent attempt to deflect attention from the
person who most obviously benefited from Kirov's removal.  The subsequent energetic
search for co-conspirators resulted in any number of people accusing each other of
crimes against the state in a desperate attempt to escape liquidation.  All of this
played directly into Stalin's hands because he could, as a result, annihilate the
members of the old political hierarchy who were likely to threaten him and, furthermore,
replace them with his own creatures who would do his bidding without questions or
remorse until they, in turn, were removed by the next round of bureaucratic
hatchetmen.

In the final analysis, there can be no question
that Josef Stalin was ultimately responsible for every action that was perpetrated while
he was Party Secretary, particularly after 1928 when he consolidated his power over the
Politburo.  The totalitarian regime he created was absolute to the point where he was
given credit for good weather and the birth of healthy children; he personally viewed
and approved all films that were allowed to be screened in the Soviet Union; he held the
power of life and death over every last one of his people.  It is unthinkable that the
Purges, which were carried out with rigorous attention to the niceties of Soviet law and
administered by a chain of command that began and ended at the top, could possibly have
occurred without his approval.

One last note: it is perhaps
somewhat ironic that one of the last notable victims of the Stalinist purges was also
the first and most public of Stalin's political enemies: Leon Trotsky, who had to wait
the better part of fifteen years before he met his fate in Mexico City in
1940.