In astrophysics and cosmology, the anthropic principle is the philosophical consideration that observations of the physical Universe must be compatible with the conscious life that observes it.

Some proponents of the anthropic principle reason that it explains why the Universe has the age and the fundamental physical constants necessary to accommodate conscious life.

The strong anthropic principle ( SAP ) as explained by Barrow and Tipler ( see variants ) states that this is all the case because the Universe is compelled, in some sense, for conscious life to eventually emerge.

Critics of the SAP argue in favor of a weak anthropic principle ( WAP ) similar to the one defined by Brandon Carter, which states that the universe's ostensible fine tuning is the result of selection bias: i. e., only in a universe capable of eventually supporting life will there be living beings capable of observing any such fine tuning, while a universe less compatible with life will go unbeheld.

The anthropic principle states that this is a necessity, because if life were impossible, no one would know it.

The term anthropic in " anthropic principle " has been argued to be a misnomer.

The anthropic principle is often criticized for lacking falsifiability and therefore critics of the anthropic principle may point out that the anthropic principle is a non-scientific concept, even though the weak anthropic principle, " conditions that are observed in the universe must allow the observer to exist ", is " easy " to support in mathematics and philosophy, i. e. it is a tautology or truism

Steven Weinberg and a number of string theorists ( see string landscape ) have used this as evidence for the anthropic principle, which suggests that the cosmological constant is so small because life ( and thus physicists, to make observations ) cannot exist in a universe with a large cosmological constant, but many people find this an unsatisfying explanation.

This has prompted attempts at anthropic explanations of the values of some of the dimensionless fundamental physical constants.

The anthropic principle is a controversial argument of why the fine-structure constant has the value it does: stable matter, and therefore life and intelligent beings, could not exist if its value were much different.

* The anthropic fine tuning of the universe: He quotes with approval Freeman Dyson, who said " the more I examine the universe and the details of its architecture, the more evidence I find that the universe in some sense must have known we were coming " and suggests there is a wide consensus amongst physicists that either there are a very large number of other universes in the Multiverse or that " there is just one universe which is the way it is in its anthropic fruitfulness because it is the expression of the purposive design of a Creator, who has endowed it with the finely tuned potentialty for life.

Astronomical existential risks might similarly be underestimated due to selection bias, and an anthropic correction has to be introduced.

This approach has led to considerable research into the anthropic principle and has been of particular interest to particle physicists, because theories of everything do apparently generate large numbers of universes in which the physical constants vary widely.

An ecosystem which has reached its climax is more resilient to perturbations ( climatic or anthropic ) than an artificial plantation.

They believe that quantum wave-functions do not collapse like the Copenhagen interpretation holds, nor that each collapse actually buds off separate universes ( like the quantum multiverse hypothesis holds ) but rather that the universe is a participatory universe: the entire universe exists as a single massive quantum superposition, and that at the end of time ( in the open universe of the Xeelee Sequence, time and space are unbounded, or more precisely, bounded only at the Cauchy boundaries of " Time-like infinity " and " Space-like infinity "), when intelligent life has collected all information ( compare the Final anthropic principle and the Omega Point ), and transformed into an " Ultimate Observer ", who will make the " Final observation ", the observation which collapses all the possible entangled wave-functions generated since the beginning of the universe.

Although this anthropic principle was originally designed as a rebuttal to the Doomsday argument ( by Dennis Dieks in 1992 ) it has general applications in the philosophy of anthropic reasoning, and Ken Olum has suggested it is important to the analysis of quantum cosmology.

The second option, common amongst philosophers who adopt anthropic mechanism, is to argue that the arguments given for incompatibility are specious: whatever it is we mean by " consciousness " and " free will ," they urge, it is fully compatible with a mechanistic understanding of the human mind and will.

An anthropic explanation of the failure of Dicke's argument was given by Weinberg.

Climax vegetation is the vegetation which establishes itself on a given site for given climatic conditions in the absence of anthropic action after a long time ( it is the asymptotic or quasi-equilibrium state of the local ecosystem ).

Again, the anthropic principle states that we can only live in one of the universes that is compatible with some form of intelligent life.

:: John Archibald Wheeler's participatory anthropic principle says that consciousness plays some role in bringing the universe into existence.

The thesis in anthropic mechanism is not that everything can be completely explained in mechanical terms ( although some anthropic mechanists may also believe that ), but rather that everything about human beings can be completely explained in mechanical terms, as surely as can everything about clockwork or gasoline engines.

The Multiverse hypothesis assumes the existence of many universes with different physical constants, some of which are hospitable to intelligent life ( see multiverse: anthropic principle ).

Tegmark suggests that statistical analyses exploiting the anthropic principle provide an opportunity to test multiverse theories in some cases.

However, the anthropic nature of the various deities that were worshiped differed among other peoples like the Egyptians and Babylonians, who sometimes thought that their gods could take an array of forms, some non-human.

* " Anthropic Coincidence "— the anthropic controversy as a segue to Lee Smolin's theory of cosmological natural selection.

This anthropic approach is often criticised in that, because the theory is flexible enough to encompass almost any observation, it cannot make useful ( i. e., original, falsifiable, and verifiable ) predictions.

Antony Flew, who spent most of his life as an atheist, converted to deism late in life because of the anthropic principle.

* 1961 — Robert Dicke argues that carbon-based life can only arise when the gravitational force is small, because this is when burning stars exist ; first use of the weak anthropic principle

He also states that "... ' anthropic ' reasoning fails to distinguish between minimally biophilic universes, in which life is permitted, but only marginally possible, and optimally biophilic universes, in which life flourishes because biogenesis occurs frequently ..." Among scientists who find the evidence persuasive, a variety of natural explanations have been proposed, e. g., the anthropic principle along with multiple universes.

These ideas did not attract much attention at that time, in part because the anthropic principle was very unpopular, in part because the new inflationary scenario did not quite work and was replaced by the chaotic inflation scenario.

The weak anthropic principle could then be applied to conclude that we ( as conscious beings ) would only exist in one of those few universes that happened to be finely tuned, permitting the existence of life with developed consciousness.

* A simple anthropic argument for why there are 3 spatial and 1 temporal dimensions.

We have only one example, rendering statistical estimates impossible, and even the example we have is subject to a strong anthropic bias.

The anthropic principle states a logical truism: the fact of our existence as intelligent beings who can measure physical constants requires those constants to be such that beings like us can exist.

A speculative solution is that many or all of these possibilities are realised in one or another of a huge number of universes, but that only a small number of them are habitable, and hence the fundamental constants of the universe are ultimately the result of the anthropic principle rather than a consequence of the theory of everything.

Almost febrile in intensity, the principle has become worldwide in application -- unfortunately at the very time that nationalist fervors can wreak greatest harm.

As an illustration of the principle of simplicity the heliocentric discovery has a peculiar appeal because it allows simplicity to be arithmetized ; ;

The greatest impact of the matching-fund principle has been in initially encouraging the poorest states and school districts to spend enough to obtain their full allocation of outside funds.

The acceptance of collective bargaining as a national policy in 1934, implicit in the writing of Section 7A of the National Industrial Recovery Act, has made it impolitic to oppose collective bargaining in principle.

gift, which has become a principle of justice.

( A formal proof for all finite sets would use the principle of mathematical induction to prove " for every natural number k, every family of k nonempty sets has a choice function.

The restricted principle " Every partially ordered set has a maximal totally ordered subset " is also equivalent to AC over ZF.

** Antichain principle: Every partially ordered set has a maximal antichain.

Nevertheless, one has to keep in mind that electrons are fermions ruled by the Pauli exclusion principle and cannot be distinguished from the other electrons in the atom.

This provision has been dormant since Queen Victoria ascended the throne, because she did not inherit Hanover under the Salic Laws of the German states, but in principle it could again become relevant in the future.

The principle it works on, the constant of simultaneity, is analogous in some ways to gravity ... One point has to be fixed, on a planet of certain mass, but the other end is portable.

Although this concept remains a guiding principle of the profession, it is a concept that has been widely critiqued within the conservation profession and is now considered by many to be " a fuzzy concept ".

This principle has frequently been called the " Sapir – Whorf hypothesis ", after him and his mentor Edward Sapir, but Whorf called it the principle of linguistic relativity, because he saw the idea as having implications similar to Einstein's principle of physical relativity.

To this end, the cosmological principle has been confirmed to a level of 10 < sup >− 5 </ sup > via observations of the CMB.

Lionel Curtis, writing in the imperialist journal The Round Table, wrote: " If the British Commonwealth can only be preserved by such means, it would become a negation of the principle for which it has stood ".

According to one principle of classification, an emergent coastline is a coastline which has experienced a fall in sea level, because of either a global sea level change, or local uplift.

If a similar dispute has been resolved in the past, the court is bound to follow the reasoning used in the prior decision ( this principle is known as stare decisis ).

David Chalmers has argued that A-consciousness can in principle be understood in mechanistic terms, but that understanding P-consciousness is much more challenging: he calls this the hard problem of consciousness.

Fred Dretske has objected to the transitivity principle on the basis that we often experience mental states that are consciously different without being aware of the conscious different.