I have to admit this question isn't very neatly thought out, but I've always been a bit puzzled by the Anthropic Principle. I realize there are various forms or "strengths" of the idea, and it's not really central to physics at all.

On one level it seems irrefutable, almost tautological. But it also reminds me of various types of Idealism, especially Berkeley's (which has always been kind of appealing). The "facts" or "truth" of physics depend on observation. A universe in which the laws of physics operate must contain observers, whose observations are ergo necessary to the existence of that particular universe.

I'm sure someone can straighten out my poor logic there. Now, to tack on "well, we can imagine other universes" seems a bit evasive. How do philosophers today generally regard the strong versions of the principle? Is ever compared to 18th century idealism? Does it have real and interesting implications, or is it just a kind of chicken-and-egg argument?

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    Even the strong anthropic principle (a physical universe must eventually produce observers) does not imply that physical facts are observer dependent. That X and Y are necessarily produced together does not make facts about X dependent on Y. SAP is, indeed, idealistic, but not in the style of Berkeley's subjective idealism, rather in the style of theistic teleology. What comes to mind is Hegel's self-awakening Spirit or Teilhard de Chardin's hominization culminating in the Omega Point.
    – Conifold
    Commented Sep 18, 2020 at 4:57
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    That makes sense, thanks. So physical universe is prior to observer and any possibility of observation. Perhaps more like Berkeley in reverse? The "leap of faith" is to our own necessary dependence on a universe largely unobservable in principle, which I guess is just the common sense assumption. I guess my puzzlement is about the broader question of observer status in physics, where I always thought Berkeley had a point, in a funny way. Commented Sep 18, 2020 at 13:50
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    Berkeley does have a point in Bohr's "old" Copenhagen interpretation and its descendants, like "consciousness causes collapse", Wheeler's "participatory universe", Rovelli's relational QM, or even "many minds" version of Everettian interpretation. Observers "co-create" the universe, so to speak, by collapsing superpositions into facts. Most physicists walked away from this when decoherence theory made clear that for the purposes of collapse the "observer" need not be anything conscious or even mind-like, it can be any macroscopic environment, but the idea is still actively discussed.
    – Conifold
    Commented Sep 18, 2020 at 20:36
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    There are several variations of the anthropic principle, including a version that seems identical to classical philosophical idealism: the universe only exists because we perceive it.This is true, and extremely profound and trivial at the same time.skepdic.com/anthropic.html
    – user47436
    Commented Sep 22, 2020 at 9:48
  • In any model based on a system without time and dynamics, the observed space, time, and matter are products of consciousness.This means subjective idealism.At the same time, it can be said about the fundamental possibility of falsification of subjective idealism. For falsification, it is necessary to prove that there is no way to construct space-time that satisfies observations based on systems without time and dynamics. Thus, a fundamental opportunity appears to verify whether we live in a world of realism or idealism. philarchive.org/rec/SMIAPI-5
    – user47436
    Commented Sep 22, 2020 at 10:33

1 Answer 1


You might argue, that if one favours the Strong Anthropic Principle (SAP), one emphasises the observation of the world as a necessary precondition for obtaining knowledge (including the knowledge that there is a universe at all) thereby taking a positivists point of view. Therefore I find it not so easy, to use the SAP as an argument on the behalf of Idealism.

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