Vitalism is the philosophical position that life is "more than the sum of its physical parts;" or, that life cannot be fully explained in physical material terms. Essentially, the physical processes of life are seen as emerging from an immaterial impulse. Aristotle is regarded as the founder of vitalism. He believed that the soul, as a form of life-energy, kept the organism alive, affecting the organism without being physically connected to it.
Early biologist support
Many prominent early biologists were vitalists. Georg Ernst Stahl (1660-1734), for example, built a comprehensive medical theory and practice on vitalistic foundations. Marie-François-Xavier Bichat (1771-1802), one of the greatest scientists of the 18th century and founder of histology, was a vitalist. Karl Ernst von Baer, who discovered the mammalian ovum, was also a vitalist.
Materialism is the viewpoint opposed to vitalism, which holds that life is nothing more than the sum of its physical parts. Materialism became the dominant philosophical viewpoint during the 20th century, and with it the non-sequitur that because vitalism cannot be scientifically proven, it is obsolete, unscientific, or even false. In reality, of course, vitalism and materialism are philosophical views and intellectual orientations, rather than "scientific" or "unscientific" opinions, and therefore inform one's approach to science. For example in medicine, a materialist scientist looks for cures solely in material terms (for example, medicines and surgery), while a vitalist looks for cures both by material means (such as medicines and surgery) and spiritual means (such as prayer).
Philosophical vitalism is often confused with the early and erroneous belief in chemistry that organic molecules can only be formed by living organisms.