In "The Star Beast" by Robert A. Heinlein, McCarthy is a politician who is against the legalization of owning a highly intelligent alien creature named Lummox. The "learned men" are a group of scientists and academics who believe that Lummox should be studied rather than owned. Despite their different views, both McCarthy and the "learned men" may be motivated by a desire to protect their own interests and maintain the status quo.
McCarthy is motivated by a desire to maintain order and uphold the law, as he believes that Lummox is a dangerous creature that poses a threat to humans. He also sees Lummox as a potential source of conflict between humans and other alien races. On the other hand, the "learned men" are motivated by their desire to study Lummox and learn more about its intelligence and abilities. They are more concerned with advancing knowledge than with maintaining order.
Despite these differences, both McCarthy and the "learned men" are motivated by a desire to protect their own interests. McCarthy is concerned with maintaining the status quo and preventing conflict, while the "learned men" are interested in advancing knowledge and understanding. In this sense, they are both motivated by a desire to protect what they perceive as valuable and important.