The Buddhist doctrine of anattā — non-self — is the most philosophically demanding of the three characteristics of existence, and the most frequently misunderstood. It does not claim that you don't exist in any sense. It claims that among the contents of your experience, there is no fixed, permanent, self-identical entity that qualifies as 'the self.' What you find instead, when you look carefully, is a rapidly flowing sequence of processes — sensations, perceptions, memories, intentions, consciousness — that are organized in ways that give rise to the functional experience of continuity, but in which no singular executive entity can be located.
The Buddha divided this phenomenology into five aggregates (khandhas): form (the body and its sensory interface), feeling-tone (vedanā — the quality of pleasant, unpleasant, or neutral that accompanies each experience), perception (the recognition and categorization of objects), mental formations (intentions, emotions, attention, volition), and consciousness (the awareness that contacts each object). The critical observation is that these five processes are not unified by a sixth thing called 'the self' — they are simply processes, and the sense of a unified experiencer is generated by their rapid coordination, not by something standing outside them.
Cognitive neuroscience arrived at a structurally identical conclusion, from a different direction. Michael Gazzaniga's split-brain experiments beginning in the 1960s revealed that the left hemisphere of the human brain contains what he called the 'interpreter' — a module that generates post-hoc explanations for actions taken by the right hemisphere, which the left hemisphere had no access to in advance. Subjects whose corpus callosum had been severed would act on a cue presented only to the right hemisphere, and then the left hemisphere would immediately produce a confident and entirely confabulated explanation for why. The self, in Gazzaniga's framing, is not a decision-maker — it is a story-generator that keeps a running narrative of decisions made by neural processes operating below the level of conscious access.
Neuroscientist and meditation teacher Sam Harris extends this: the sense of being a subject located 'behind the eyes' — what philosophers call the felt sense of a Cartesian theater — is not a perception of a real object. It is a cognitive construction, and like all constructions, it can be seen through. The Default Mode Network (DMN), a set of brain regions most active during mind-wandering, self-referential thought, and rumination, is the neural substrate of this narrative self. Research consistently shows that experienced meditators exhibit marked down-regulation of DMN activity during practice, and that this down-regulation correlates with subjective reports of reduced ego-attachment, reduced rumination, and increased equanimity.
The practical implication of anattā is significant and underappreciated. A large category of psychological suffering is ego-related — it is suffering that arises because events feel threatening to the narrative self: the shame of failure (threat to self-image), the anxiety of uncertainty (threat to the story's future), the anger of disrespect (threat to status within the story). None of these are responses to bare events. They are responses to what the events mean for the narrative. Training the mind to see that the narrative is a construction — useful but not ultimate — creates the possibility of experiencing the events without the secondary suffering layer that the narrative generates.