Editing Anthropic principle (section)

== Reception and controversies ==
Carter has frequently expressed regret for his own choice of the word "anthropic", because it conveys the misleading impression that the principle involves ''[[Anthropocentrism|humans in particular]]'', to the exclusion of [[Extraterrestrial intelligence|non-human intelligence]] more broadly.<ref>e.g. Carter (2004) op. cit.</ref> Others<ref>e.g. message from [[Martin Rees]] presented at the Kavli-CERCA conference (see video in External links)</ref> have criticised the word "principle" as being too grandiose to describe straightforward applications of [[selection effects]].

A common criticism of Carter's SAP is that it is an easy ''[[deus ex machina]]'' that discourages searches for physical explanations. To quote Penrose again: "It tends to be invoked by theorists whenever they do not have a good enough theory to explain the observed facts."<ref>{{Cite book |author=Penrose, R. |author-link=Roger Penrose |title=The Emperor's new mind |url=https://archive.org/details/emperorsnewmindc00penr |url-access=registration |publisher=Oxford University Press |isbn=978-0-19-851973-7 |year=1989 |chapter=10 }}</ref>

Carter's SAP and Barrow and Tipler's WAP have been dismissed as [[truism]]s or trivial [[tautology (logic)|tautologies]]—that is, statements true solely by virtue of their [[logical form]] and not because a substantive claim is made and supported by observation of reality. As such, they are criticized as an elaborate way of saying, "If things were different, they would be different",{{Citation needed |date=September 2022 }} which is a valid statement, but does not make a claim of some factual alternative over another.

Critics of the Barrow and Tipler SAP claim that it is neither testable nor [[falsifiability|falsifiable]], and thus is not a [[scientific method|scientific statement]] but rather a philosophical one. The same criticism has been leveled against the hypothesis of a [[multiverse]], although some argue<ref>[https://blogs.scientificamerican.com/guest-blog/are-parallel-universes-unscientific-nonsense-insider-tips-for-criticizing-the-multiverse/ Are parallel universes unscientific nonsense? Insider tips for criticizing the multiverse]  Tegmark, Max. February 4, 2014.</ref> that it does make falsifiable predictions. A modified version of this criticism is that humanity understands so little about the emergence of life, especially intelligent life, that it is effectively impossible to calculate the number of observers in each universe. Also, the prior distribution of universes as a function of the fundamental constants is easily modified to get any desired result.<ref>{{Cite journal |author=Starkman, G. D. |author2=Trotta, R. |title=Why anthropic reasoning cannot predict Λ |journal=Physical Review Letters |volume=97 |page=201301 |year=2006 |doi=10.1103/PhysRevLett.97.201301 |pmid=17155671 |issue=20 |bibcode=2006PhRvL..97t1301S |arxiv=astro-ph/0607227 |s2cid=27409290 }} See also this [http://www.physorg.com/news83924839.html news story.]</ref>

Many criticisms focus on versions of the strong anthropic principle, such as Barrow and Tipler's ''anthropic cosmological principle'', which are [[Teleology|teleological]] notions that tend to describe the existence of life as a ''necessary prerequisite'' for the observable constants of physics. Similarly, [[Stephen Jay Gould]],<ref>{{Cite conference |last=Gould |first=Stephen Jay |year=1998 |title=Clear thinking in the sciences |book-title=Lectures at Harvard University }}</ref><ref>{{Cite book |last=Gould |first=Stephen Jay  |year=2002 |title=Why people believe weird things: Pseudoscience, superstition, and other confusions of our time |publisher=W.H. Freeman |isbn=978-0-7167-3090-3  }}</ref> [[Michael Shermer]],<ref>{{Cite book |last=Shermer |first=Michael |year=2007 |title=Why Darwin matters |publisher=Macmillan |isbn=978-0-8050-8121-3 |url=https://archive.org/details/whydarwinmatters00mich }}</ref> and others claim that the stronger versions of the anthropic principle seem to reverse known causes and effects. Gould compared the claim that the universe is fine-tuned for the benefit of our kind of life to saying that sausages were made long and narrow so that they could fit into modern hotdog buns, or saying that ships had been invented to house [[barnacle]]s.{{citation needed|date=March 2024}} These critics cite the vast physical, fossil, genetic, and other biological evidence consistent with life having been [[fine-tuned universe|fine-tuned]] through [[natural selection]] to adapt to the physical and geophysical environment in which life exists. Life appears to have adapted to the universe, and not vice versa.

Some applications of the anthropic principle have been criticized as an [[argument by lack of imagination]], for tacitly assuming that carbon compounds and water are the only possible chemistry of life (sometimes called "[[carbon chauvinism]]"; see also [[alternative biochemistry]]).<ref>e.g. {{Cite journal |author=Carr, B. J. |author2=Rees, M. J. |title=The anthropic principle and the structure of the physical world |journal=Nature |volume=278 |pages=605–612 |year=1979 |doi=10.1038/278605a0 |bibcode=1979Natur.278..605C |issue=5705 |s2cid=4363262 |author2-link=Martin Rees |author-link=Bernard Carr }}</ref> The range of [[dimensionless physical constant|fundamental physical constant]]s consistent with the evolution of carbon-based life may also be wider than those who advocate a [[fine-tuned universe]] have argued.<ref>{{Cite book| last=Stenger| first=Victor J.| author-link=Victor Stenger |year=2000 |title=Timeless reality: Symmetry, simplicity, and multiple universes |publisher=Prometheus books |isbn=978-1-57392-859-5 }}</ref> For instance, Harnik et al.<ref>{{Cite journal |author=Harnik, R. |author2=Kribs, G. |author3=Perez, G. |year=2006 |title=A Universe without weak interactions |journal=Physical Review |volume=D74 |page=035006 |doi=10.1103/PhysRevD.74.035006 |arxiv=hep-ph/0604027 |bibcode=2006PhRvD..74c5006H |issue=3 |s2cid=14340180 }}</ref> propose a [[Weakless Universe]] in which the [[weak nuclear force]] is eliminated. They show that this has no significant effect on the other [[fundamental interaction]]s, provided some adjustments are made in how those interactions work. However, if some of the fine-tuned details of our universe were violated, that would rule out complex structures of any kind—[[star]]s, [[planet]]s, [[galaxies]], etc.

[[Lee Smolin]] has offered a theory designed to improve on the lack of imagination that has been ascribed to anthropic principles. He puts forth his [[Lee Smolin#Cosmological natural selection|fecund universes]] theory, which assumes universes have "offspring" through the creation of [[black hole]]s whose offspring universes have values of physical constants that depend on those of the mother universe.<ref>{{Cite book |author=Lee Smolin |author-link=Lee Smolin |editor=Tyson, Neil deGrasse |editor-link=Neil deGrasse Tyson |editor2=Soter, Steve |editor2-link=Steven Soter |year=2001 |title=Cosmic horizons: Astronomy at the cutting edge |publisher=The New Press |isbn=978-1-56584-602-9 |pages=[https://archive.org/details/isbn_9781565846029/page/148 148–152] |url=https://archive.org/details/isbn_9781565846029/page/148 }}</ref>

The philosophers of cosmology [[John Earman]],<ref>{{Cite journal |author=Earman John |year=1987 |title=The SAP also rises: A critical examination of the anthropic principle |journal=American Philosophical Quarterly |volume=24 |pages=307–317 |jstor=20014208 |url=https://personal.lse.ac.uk/robert49/teaching/ph201/Week14_xtra_Earman.pdf}}</ref> [[Ernan McMullin]],<ref>McMullin, Ernan. (1994). "Fine-tuning the Universe?" In M. Shale & G. Shields (ed.), ''Science, technology, and religious ideas'', Lanham: University Press of America.</ref> and [[Jesús Mosterín]] contend that "in its weak version, the anthropic principle is a mere tautology, which does not allow us to explain anything or to predict anything that we did not already know. In its strong version, it is a gratuitous speculation".<ref>Mosterín, Jesús. (2005). Op. cit.</ref> A further criticism by Mosterín concerns the flawed "anthropic" inference from the assumption of an infinity of worlds to the existence of one like ours:

{{Blockquote|The suggestion that an infinity of objects characterized by certain numbers or properties implies the existence among them of objects with any combination of those numbers or characteristics [...] is mistaken. An infinity does not imply at all that any arrangement is present or repeated. [...] The assumption that all possible worlds are realized in an infinite universe is equivalent to the assertion that any infinite set of numbers contains all numbers (or at least all Gödel numbers of the [defining] sequences), which is obviously false.}}