Ernst Mach
Positivist · Europe · 1838 to 1916
Austrian physicist and thinker who held that science should describe what can be sensed, and drop what no one can observe.
What it is
Ernst Mach (1838 to 1916) was an Austrian physicist who also became a philosopher of science. He is remembered for his work on sound and shock waves, which gave his name to the Mach number, and for arguing that science should stay close to what can be observed.
He was born in Moravia, took his doctorate in physics at Vienna in 1860, and taught at Graz, Prague and then Vienna, where he became a professor in 1895. A stroke in the late 1890s forced him to retire in 1901. He kept writing and lecturing afterwards, and died in 1916.
The main ideas
- Science rests on experience. Mach held that scientific statements should be tied to what can be observed. A claim that no observation could ever check does not belong in natural science.
- Sensations as the starting point. In The Analysis of Sensations (1886) he treated sensations as the material from which knowledge is built.
- No absolute space or time. He rejected the idea of absolute space and time.
- Inertia and the rest of the universe. He proposed that a body's resistance to changes of motion arises from its relation to all other matter in the universe. This is called Mach's principle.
What it looks like in practice
Imagine someone told that all motion takes place against a fixed, unchanging background of absolute space, though no measurement could ever find that background. Mach would ask what could be observed to show it, other than how things move in relation to one another. This is an illustration of his way of questioning, not a passage from his writing.
Books and moments
- Mach bands. He described the effect by which the eye sees bright or dark bands near the edge between two areas of sharply different light.
- 1887, shock waves. His work with photography on moving projectiles and sound laid the base for the study of supersonic flight. The ratio of an object's speed to the speed of sound is named the Mach number.
- The Analysis of Sensations (1886) sets out his view of knowledge and the mind.
- Knowledge and Error (1905) came out after his retirement.
- Einstein. Mach's rejection of absolute space and time influenced Einstein, who credited him as a philosophical forerunner of the theory of relativity.
Questions and criticism
- Did he reduce the world to sensations? He held that all knowledge comes from sensation. Whether that means the world is nothing but sensations is a question each reader has to weigh.
Close neighbours
Rudolf Carnap's page shows a later movement, logical empiricism, to whose background Mach's ideas contributed.
Written by epchē in our own words, and checked against independent sources on 29 October 2026. The sources are listed below.
Who they connect to
Influenced
- Rudolf Carnap · The Vienna Circle took up his demand that science speak only of what can be tested in experience.
Influenced by
- David Hume · He called Hume a forerunner and shared his view that the self and the world are bundles of sensations.
Other Positivist thinkers
- Auguste Comte · 1798 to 1857
- Herbert Spencer · 1820 to 1903
- Emile Durkheim · 1858 to 1917
- Moritz Schlick · 1882 to 1936
- Rudolf Carnap · 1891 to 1970
- A. J. Ayer · 1910 to 1989
Sources we used
- Ernst Mach · Stanford Encyclopedia of Philosophy, read on 29 October 2026
- Ernst Mach · Encyclopaedia Britannica, read on 29 October 2026