Give an example from the crucible that demonstrates that certainty can be dangerous.

kennedy creates personal credibility by saying he is more than fit to lead. he talks about the sixty day period that he constructed administration, and says based on that he will be an acceptable leader.

jfk has a great reputation as an american citizen. he fought in wwii, and earned the navy and marine corps medal. he saved several men on his pt-109 patrol torpedo boat after an attack by the japanese navy. he also served in congress for the 11th congressional district for massachusetts, and served three terms in the house of representatives.

explanation:

the speech this question is referring to is president kennedy's special message to the congress on urgent national needs, may 25, 1961

kennedy responds in a very direct and concrete way to those thinking that communism is a positive system:

"yet their aggression is more often concealed than open. they have fired no missiles; and their troops are seldom seen. they send arms, agitators, aid, technicians and propaganda to every troubled area. but where fighting is required, it is usually done by others--by guerrillas striking at night, by assassins striking alone--assassins who have taken the lives of four thousand civil officers in the last twelve months in vietnam alone--by subversives and saboteurs and insurrectionists, who in some cases control whole areas inside of independent nations." (kennedy)

president kennedy presents communism as cowardly, as a hidden and treacherous weapon that strikes from the shadows like thieves, he represents the system as not even being capable of showing and open and overt attack or confrontation. to finish up the response, he expresses that the system attacks even a country's idependence and freedom.