The absolute state of mind refers to a core disposition in society and the individual. In society, it is clearest in religious, especially fanatical, fundamentalism; in the individual, in a narcissistic fundamentalism described by post-Kleinians as pathological narcissistic structures. Historians and sociologists also see normal and rational strategy in a range of fundamentalist groups, and for psychoanalysts, pathological narcissistic structures are extremes also found in ordinary people. My aim is to draw on recent scholarship to extract a core theme - the absolute state of mind - that characterizes this fundamentalist disposition in its extremism and its rationality, and to describe it psychoanalytically.