Final answer:
Larry Bartels found that on economic issues, both the Democratic and Republican parties are more responsive to the preferences of the upper and middle classes than the lower class. This trend aligns with research showing a strong influence of wealthy Americans on government policy and makes evident the limitations of the two-party system in representing class interests equitably.
Step-by-step explanation:
Political scientist Larry Bartels' research indicates that on economic issues, both the Democratic and Republican parties are more responsive to the preferences of the upper and middle classes than the lower class. This reflects a broader trend where economic policies tend to favor the wealthy, as also observed by political scientist Martin Gilens' study, which revealed a strong correlation between the preferences of wealthy Americans and the policy actions of the U.S. government.
The increasing polarization between parties further complicates the issue. As Republican and Democratic respondents show widely opposing views on value statements related to government regulation and the role of government, the alignment with class interests could also reflect the partisan divide and focus on maintaining a moderate stance to capture the most votes.
Despite the potential advantages of a multiparty system, such as the representation of a broader range of interests, the U.S. has maintained its two-party system since the Civil War. While the system allows all citizens to choose if either party aligns with their needs, research like Bartels' demonstrates the systemic bias towards the interests of the upper class within the current two-party framework.