Socrates is widely regarded as the father of Western philosophy due to his profound influence on subsequent philosophical thought and his emphasis on critical thinking and ethical inquiry.

Utilitarianism, as propounded by philosophers like Jeremy Bentham and John Stuart Mill, focuses on maximizing overall happiness or pleasure and minimizing pain or suffering as the basis for moral decision-making.

Immanuel Kant's categorical imperative is a moral principle that emphasizes acting only according to those maxims that can be universalized as a law for all rational beings.

René Descartes' famous statement 'cogito ergo sum' (I think, therefore I am) expresses the idea that the act of thinking provides indubitable evidence of one's own existence.

John Locke's social contract theory suggests that individuals consent to form a political society in order to secure their natural rights, such as life, liberty, and property.

Existentialism, as espoused by philosophers like Jean-Paul Sartre and Albert Camus, emphasizes the importance of individual freedom, choice, and responsibility in shaping one's existence.

Friedrich Nietzsche's perspectivism suggests that there is no single, objective truth, but rather multiple perspectives and interpretations of reality.

Dialectic, as explored by philosophers like Socrates and Plato, involves the clash of opposing ideas or viewpoints in order to arrive at a deeper understanding of a topic.

Ludwig Wittgenstein's linguistic determinism suggests that the structure of a language influences the way we think and perceive the world.

Phenomenology, as developed by philosophers like Edmund Husserl and Martin Heidegger, focuses on the study of consciousness and the lived experiences of individuals.

Jacques Derrida's deconstruction involves analyzing and critiquing the assumptions, structures, and power dynamics embedded in language and texts.

Pragmatism, as espoused by philosophers like William James and John Dewey, emphasizes the importance of practical consequences and the usefulness of ideas in determining their truth or value.

Friedrich Nietzsche's theory of 'the will to power' suggests that the fundamental driving force behind human behavior is the desire for power and self-assertion.

Existential angst, as explored by philosophers like Søren Kierkegaard and Jean-Paul Sartre, refers to the anxiety and uncertainty that arise from the realization of one's freedom and responsibility in shaping one's existence.

Friedrich Nietzsche's theory of 'the eternal recurrence' posits that the universe and all events within it will repeat themselves endlessly in an infinite loop.