The definition of empathy differs among the domains which deal with it. Introduced in medicine and psychology in the late 19th-early 20th century, it received contrasting definitions from philosophers and psychopathologists. The neuroscience paradigm of empathy for pain allowed us to identify two components of empathy, one automatic, bottom-up, and one cognitive, top-down. The role of mirror neurons in this context appears to be central. Empathy is influenced by perception of other, closeness, belonging to a social group, and gender, with women empathizing more than men. The areas involved are the self-other distinction areas (dorsomedial prefrontal cortex and temporoparietal junction), the anterior insula, and the anterior cingulate. The activations identified in the brain allow for better understanding the phenomenon, but not to draw a consensus definition. Rather than providing responses, the neurosciences send back to philosophy new, formidable questions to be asked.