When we talk about Plato's idea of a philosopher-king, we need to think about the ethical issues it brings up. The idea sounds good at first—having a wise person in charge could lead to better decisions. Philosophers know a lot about what is right and good. But, there are several problems that come with this idea.

First, there's the issue of power. If one philosopher holds all the power, it could lead to bad things. When one person has complete control, they might ignore the rights of others and not listen to different opinions. A ruler with their own ideas of what is good might overlook the many beliefs that people in society hold.

Second, we need to think about who gets to be a philosopher-king. Not every philosopher is a good person. If they lack moral values, their rule could hurt others. History shows us that being smart doesn’t always mean someone will do the right thing. So, believing that philosopher-kings will always be good is unrealistic.

Third, the citizen's role is less important in this model. A strong and fair society needs everyone to participate. But in the philosopher-king setup, it seems like only a few people can really understand what is right. This kind of setup makes people feel left out and undervalues their opinions.

In summary, while Plato’s philosopher-king idea sounds appealing because it suggests wisdom and fairness, we must consider the ethical issues it raises. Concentrating so much power in one person could lead to problems. Finding a balance between knowledge and authority is very important when we think about creating a just and fair society.