Final answer:
James Madison stated that human nature and economic disparities were the primary causes of factions, with the unequal distribution of property being a significant factor.
Step-by-step explanation:
James Madison argued that the primary cause of factions was human nature which manifests in various conflicting interests, especially the unequal distribution of property. He believed that economic disparities lead to the formation of factions, as those with property and those without develop distinct interests within society. Additionally, other sources like political ideologies and passions could also divide society, but Madison emphasized that the most enduring source was economic in nature.