---
title: "Definition of life"
chunk: 3/3
source: "https://en.wikipedia.org/wiki/Definition_of_life"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T04:17:39.577696+00:00"
instance: "kb-cron"
---

=== Mechanism to vitalism ===
Aristotelianism was questioned in the 1630s by René Descartes in Treatise on Man, which described living beings as automata, built on muscles, bones, and organs instead of cogs and pistons. Shortly afterwards Isaac Newton postulated the three laws of motion, and final causation was no longer considered valid. However, as the knowledge about plants and animals grew, it soon became clear that their working was fundamentally different to that of artificial machines. Scientists proposed vitalism to explain that a "vital force" made living organisms work.
In the 18th century, Immanuel Kant said that living organisms are built with a design, but as nature lacks a designer, it could only mean that living beings are naturally teleological and incapable of being explained purely by a framework of forces like Newton's laws of motion.

=== Emergentism ===
In 1828, Friedrich Wöhler synthesised urea, plainly a chemical of life, launching the discipline of organic chemistry. This supported the view that life was built out of chemical reactions. This philosophical viewpoint, later called emergentism, rejected vitalism. It proposed instead that living matter is composed by the same basic physical stuff as non-living matter, and is subject to the laws of physics. As matter organization grows, it generates new properties and patterns that can not be explained at the level of physics.
In 1859, Charles Darwin published his book On the Origin of Species. It argued in its closing paragraph that "There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one", and that "endless forms most beautiful and most wonderful have been, and are being, evolved." He intentionally avoided the question of the origin of life, but assumed that life could have emerged from non-living matter. More recently, scientists have come to see both life and the origin of life as processes governed by the laws of chemistry.

== References ==

== Bibliography ==
Aguilera Mochón, Juan Antonio (2016). La vida no terrestre: estamos solos en el universo? [Non-terrestrial life: are we alone in the universe?] (in Spanish). Spain: RBA. ISBN 978-84-473-8665-9.
Bennett, Jeffrey (2017). Life in the universe. United States: Pearson. pp. 3–4. ISBN 978-0-13-408908-9.
Cleland, Carol (2019). The quest for a universal theory of life. Cambridge University Press. ISBN 978-0-521-87324-6.