 The division of the legislature into an upper and lower house wasn 't questioned either , despite the obscure origins of the English House of Lords and its role as the representative of the hereditary nobility . Americans had seldom known any but bicameral legislatures , both in Britain and in most state governments . The main exceptions to this were the dysfunctional Confederation Congress and the unicameral Pennsylvania legislature , which was seen as quickly vacillating between partisan extremes after each election . Experience had convinced the delegates that an upper house was necessary to tame the passions of the lower classes against the interests of wealthy merchants and landowners . Since America had no native hereditary aristocracy , the character of this upper house was designed to protect the interests of this wealthy elite , the " minority of the opulent , " against the interests of the lower classes , who constituted the majority of the population . 
