Bergson's Creative Evolution (1907) is both his most ambitious and his most controversial work. In it, he takes the account of duration and applies it to the entire history of life on earth.
Darwinian evolution, as Bergson reads it, has a fundamental philosophical problem: it explains the mechanism of evolution (natural selection acting on random variation) without explaining the direction or creativity of evolutionary history. Random variation plus selection can produce change, but can it produce genuine novelty? Can it explain the emergence of entirely new forms of organization, new kinds of perception, new levels of complexity?
Bergson argues that life shows an irreducible creative tendency that cannot be fully explained by mechanism. He calls this the elan vital (vital impulse or vital force): not a mysterious supernatural substance but a way of describing the intrinsic tendency of life to overflow its current forms, to push toward new possibilities, to create rather than merely vary. The elan vital is not a thing added to biology. It is a description of the directionality and creativity that biological processes exhibit.
The analogy he uses most often is a shell bursting: the fragments fly outward from a single explosive center. The history of life is like this, with different lineages (plants, animals, humans) as the fragments, each carrying the original impulse in a different direction. No single fragment expresses the whole impulse; each represents a particular way the original energy resolved itself.
Human intelligence, on Bergson's account, is one particular evolutionary solution to the problem of action: it works by decomposing reality into fixed, static, spatial units that can be manipulated and combined. This is enormously practical. It is what science and technology are built on. But it is also what produces the philosophical mistake about time: intelligence is constitutionally inclined to spatialize, to freeze, to analyze into static parts. It cannot, by itself, grasp duration, movement, or life as living, because grasping these requires a different faculty.
Bergson proposes intuition as this alternative faculty: not mystical feeling but a kind of intellectual sympathy or coincidence with the moving reality of things, an effort to think in duration rather than about it. Philosophy, for Bergson, is the practice of cultivating intuition as a counterweight to intelligence's tendency to spatialize everything.
The elan vital has been much criticized and much misunderstood. It was often read as a commitment to vitalism in the strong sense: the claim that life requires a special non-physical substance that physics and chemistry cannot account for. This reading has generally been abandoned. Contemporary Bergsonian scholars like Keith Ansell-Pearson argue that Bergson's position is better understood as a form of emergentism: the claim that life exhibits properties and tendencies that are not reducible to their physical substrate, not because of a special substance but because of the organization and dynamic of the whole. This is a defensible scientific and philosophical position.