Final answer:
The rhetorical device used in Eisenhower's speech is polysyndeton, which emphasizes the complexity and magnitude of the defense challenges mentioned.
Step-by-step explanation:
The rhetorical device used in the bolded sentence of Dwight D. Eisenhower's military-industrial complex speech is polysyndeton, which is the use of multiple conjunctions in close succession. This device aims to slow down the pace of the reading, highlight the quantity or complexity of the issues addressed, and add a sense of gravity or urgency to the list of potential problems facing the nation. By explicitly listing the various expansive pursuits, Eisenhower emphasizes the multifaceted nature of challenges brought on by vast defense improvements and its implications on democratic institutions and societal norms.