Which philosopher is known for shifting philosophical focus to ethics and human behavior?

Socrates is known for his significant contributions to ethics and human behavior, effectively shifting the focus of philosophy toward these areas. He emphasized the importance of self-examination and moral inquiry, famously asserting that "the unexamined life is not worth living." Through his method of questioning—now known as the Socratic method—he encouraged critical dialogue and reflection on moral concepts such as justice, virtue, and the good life.

This focus on ethics marked a departure from earlier philosophical traditions that primarily concerned themselves with natural philosophy and cosmology. Socratic philosophy laid the groundwork for later ethical theories, making ethics a central concern in Western philosophy. While Plato, as Socrates' student, also contributed significantly to ethical thought and Aristotle later developed it further, it was Socrates who initiated this shift by prioritizing moral questions and the complexities of human behavior.