Final answer:
Adam Smith, the father of modern economics, believed that economic activity is an innate human drive, influenced by both self-interest and altruistic principles.
Step-by-step explanation:
The thinker who argues that economic activity is an innate human drive is Adam Smith, often referred to as the father of modern economics. According to Smith, while individuals may be self-interested, they also possess natural tendencies that lead them to care about the well-being of others. This concept is clearly presented in the opening sentence of his book, The Theory of Moral Sentiments, demonstrating that individuals are not guided by self-interest alone but also by altruistic principles. Through this lens, it reaffirms the idea that there is an innate drive in humans to engage in economic activities, not only for personal gain but also with consideration for the happiness of others.