Paris, 1859–1941

Henri Bergson

Real time is not a line of instants. It is duration: a continuous, indivisible flow in which the past lives on in the present, as each note of a melody is heard through the ones before it. Clocks, and physics, measure something else.

A black-and-white photograph of a balding man with a moustache, in a dark jacket and high collar, looking to one side — **Henri Bergson**, photographic portrait, early 20th century. In 1922 he faced Einstein in Paris, and lost the argument in the eyes of most physicists.

The view

Bergson was the most celebrated French philosopher of his day. He taught at the Collège de France, his lectures drew crowds from far beyond the university, and in 1927 he received the Nobel Prize in Literature. His first book, Time and Free Will (1889), introduced the idea that runs through all his work: duration, or durée.

Duration is time as it is lived. Its moments are not separate and side by side, like points on a line. They interpenetrate: the present is coloured by everything that led to it, so that no two moments are ever the same. When we picture time as a line, or measure it with a clock, we turn it into something else. We spatialise it, and lose what makes it time.

The argument

Two kinds of multiplicity. Sheep in a field are many in the way that points are many: distinct, countable, laid out together. The states of a mind are many in another way. They melt into one another, like the notes of a tune, which we hear as a whole and not as a series of sounds. Time belongs to the second kind. To count it is to treat it as the first.

The cinematograph. In Creative Evolution (1907) Bergson compares the intellect to a film camera. It takes snapshots of a changing world, then fakes the movement by running the stills through an apparatus. The movement is not in the frames, and no number of frames will add up to it.

The mechanism of our ordinary knowledge is cinematographic. Bergson, Creative Evolution (1907), chapter 4, our translation

Zeno's mistake. This is why, for Bergson, Zeno's arrow seems to be at rest: Zeno replaces the flight with the line it leaves behind, and then asks where the motion went. Motion is indivisible; only its trajectory can be cut up.

Freedom and novelty. Because duration never repeats, the future is genuinely new. A free act springs from the whole of a person's past, and cannot be predicted by treating the person as a set of separable states. Evolution, too, is creative: life invents.

The debate with Einstein

On 6 April 1922, Einstein spoke at the Société française de philosophie in Paris, and Bergson rose to reply. He did not reject relativity's physics. He argued that its many times were not all equally real: only one is lived, and the others are ways of calculating. Of Paul Langevin's travelling twin, who returns younger than his brother, Bergson said that the slowed time was never experienced by anyone. Einstein's reply is reported as brisk: there is psychological time and physical time, and no third time of the philosophers.

Bergson set out his case in Duration and Simultaneity (1922). Most physicists judged that he had misunderstood the twins, whose asymmetry is real and measurable. But the clash had consequences beyond physics. When Einstein's Nobel Prize was presented, the speech noted that Bergson had challenged relativity, and the prize was awarded for other work.

Duration as Bergson describes it: one continuous movement, in which each moment carries the ones before it, like a melody in which every note is heard through the last.

Where he meets Deutsch

Bergson and Deutsch attack the same picture from opposite sides. Both think the common-sense image of time, a line of instants with a "now" sweeping along it, is confused. Bergson says it spatialises time and leaves out becoming. Deutsch says the moving now is incoherent. Neither accepts Newton's equably flowing time.

They also share a passion for the open future. Bergson's creative evolution and his defence of free will are close in spirit to Deutsch's view that the future is open and that the growth of knowledge is genuinely creative.

Where they part

The frames. This is the deepest clash on the site. Deutsch describes a moving object as a sequence of still snapshots, and compares them, in so many words, to the frames of a film. For Bergson, that is precisely the intellect's illusion: frames can only imitate a movement that is real and indivisible. For Deutsch there is nothing beyond the frames. Remove the projector, and the frames, related by law, are the motion.

Lived time or physical time. Bergson takes lived duration to be the real time, and physics to be an abstraction from it. Deutsch reverses the priority: the physics of snapshots is fundamental, and lived time is explained by the perceptions and memories within each snapshot.

Relativity. Bergson sought to keep a single real time despite relativity. Deutsch uses relativity to show that there is no objective now, and builds on it.

Freedom. Bergson grounds free will in the indivisible flow of duration. Deutsch grounds it in the multiverse, where alternatives really exist.

Bergson and Deutsch side by side
	Bergson	Deutsch
Does time flow?	Yes: duration is pure flow.	No. The idea is incoherent.
Is motion a series of snapshots?	No; that is the cinematographic illusion.	Yes; the snapshots are the motion.
Which time is real?	Lived duration.	The physical relations between snapshots.
Is the future open?	Yes, through creative novelty.	Yes, relative to observers, in the multiverse.

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