More Is Different by Anderson, P. W. (1972)

Complexity, Philosophy
(Anderson 1972)

This is a fundamental paper discussing the fundamental laws of Physics and their relations with complexity.

Reductionism doesn’t imply constructionism

It is generally accepted that the fundamental laws governing our Universe are relatively simple. We feel we understand many of these laws quite well. However, understanding these fundamental laws are far from enough to actually describe and reconstruct all phenomena we witness.

The main fallacy in this kind of thinking is that the reductionist hypothesis does not by any means imply a “constructionist” one: The ability to reduce everything to simple fundamental laws does not imply the ability to start from those laws and reconstruct the universe. In fact, the more the elementary particle physicists tell us about the nature of fundamental laws, the less relevance they seem to have to the very real problems of the rest of science, much less to those of society.

Whenever we change scale, although the same fundamental laws still apply, entirely new properties and behavior emerge. Understanding those requires extensive research that Anderson feels is as fundamental as any. This interesting charts taken from the article illustrates how scale change affects the way we study phenomena:

Solid-state or many body physics Elementary particle physics
Chemistry Many-body physics
Molecular biology Chemistry
Cell biology Molecular biology
Psychology Physiology
Social sciences Psychology


This paper is without a doubt a major work — I’m certainly not the first to say this. I believe this paradigm shift the author advocates has profoundly changed many areas of science and humanities — and is still having a great impact.

The fact that profound changes of dynamics occur when changing scale is key to understanding nature and the seemingly strange laws which govern it. I also believe that we will never achieve anything close to open-ended Evolution, artificial life or even artificial Intelligence if we cannot re-create the conditions for this phenomena to happen. Obviously, this doesn’t say anything about what we should create, but I think that once we observe this in an artificial system, we will be a lot closer to the goal.


  1. . . "More Is Different". Science 177 (4047). American Association for the Advancement of Science:393–96. DOI.
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