We had philosophy as a compulsory subject at school, where we either read entire books or sections of them. The following are the ones you should have heard:
Aristotle: Nicomachean Ethics
What's this about? It deals, as in words, with the doctrine of morality or virtue. Through virtue man fulfills his destiny, which is that he attains his natural perfection and thereby becomes happy. For Aristotle, therefore, the goal of man is the starting point of ethical consideration. Just as all living things strive for good, so also man: his highest good, the goal of all his actions, is bliss, and ethical discussion will show us that the same is to be found only in the exercise of virtue.
John Stuart Mill: Utilitarianism
What's this about? Basic thesis: An action is justified if it promotes happiness. If she diminishes or threatens it, then she's wrong. Happiness is joy, the absence of pain. Why is this still so important today? Because it's about the question of "right or wrong. " She's still killing us today. Examples are pre-implantation diagnostics, euthanasia, tax evasion. Mill's work provides food for thought in order to better deal with these questions.
Platon: Politeia
What's it all about? For ten books, the Plato fights with other men, most of the dialogues are invented. First of all, it is about justice, and then a system for the ideal construction of a state emerges. It reflects Plato’s despair for Attic democracy and the unjust death sentence passed by the People’s Court on Socrates. The purpose of the ideal community is to realize the idea of goodness and to educate its citizens. Just as in the cosmos and in the soul, a harmonious wholeness should also be realized in the ideal state. There is a structural analogy between the individual and the state: Justice as an orderly self-relation in the soul of the individual has its equivalent in the orderly self-relation of the Polis. All citizens and states provide for their well-being by integrating themselves harmoniously into the whole and serving it.
René Descartes: Meditations on the First Philosophy
What’s it all about? Descartes reverses his world view and assumes that everything he had believed so far is wrong. Including his body, his consciousness, the world and what his eyes see. He doubts the principles of mathematics and science. And that’s what it’s all about: the methodical doubt.
Immanuel Kant: The Metaphysics of Morals
What’s it all about? Kant bases every right on the right to freedom for all people. His doctrine of virtue is about physical, spiritual and moral perfection – and about the happiness of the community. He derives duties and virtues on the basis of reason.
From experience I can say that Kant is the shittiest writer that’s why I suggest you read other summaries of him. Good luck bro