Self-Indication Assumption
Encyclopedia
The Self Indication Assumption (SIA
)Nick Bostrom originally used the term SIA in a slightly different way. What is here referred to as SIA, he referred to as the combined SSA+SIA, a philosophical principle defined by Nick Bostrom
, one of the two major schools of anthropic probability (the other being the Self-Sampling Assumption
(SSA)), states that:
Note that "randomly selected" is weighted by the probability of the observers existing: under SIA you are still unlikely to be an unlikely observer, unless there are a lot of them.
For instance, if there is a coin flip that on heads will create one observer, while on tails they will create two, then we have three possible observers (1st observer on heads, 1st on tails, 2nd on tails), each existing with probability 0.5, so SIA assigns 1/3 probability to each. Alternately, this could be interpreted as saying there are two possible observer (1st observer, 2nd observer on tails), the first existing with probability one and the second existing with probability 1/2, so SIA assigns 2/3 to being the first observer and 1/3 to being the second - which is the same as the first interpretation.
This is why SIA gives an answer of 1/3 probability of heads in the Sleeping Beauty Problem
.
Notice that unlike SSA
, SIA is not dependent on the choice of reference class, as long as the reference class is large enough to contain all subjectively indistinguishable observers. If the reference class is large, SIA will make it more likely, but this is compensated by the much reduced probability that the agent will be that particular agent in the larger reference class.
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
.
Ken Olum has written in defense of the SIA. Nick Bostrom
and Milan Cirkovic have critiqued this defense.
Sia
-People:*Sia Berkeley , British actress*Sia Figiel , Samoan novelist, poet and painter*Sia Furler , Australian singer...
)Nick Bostrom originally used the term SIA in a slightly different way. What is here referred to as SIA, he referred to as the combined SSA+SIA, a philosophical principle defined by Nick Bostrom
Nick Bostrom
Nick Bostrom is a Swedish philosopher at the University of Oxford known for his work on existential risk and the anthropic principle. He holds a PhD from the London School of Economics...
, one of the two major schools of anthropic probability (the other being the Self-Sampling Assumption
Self-Sampling Assumption
The self-sampling assumption , one of the two major schools of anthropic probability , states that:...
(SSA)), states that:
- All other things equal, an observer should reason as if they are randomly selected from the set of all possible observers.
Note that "randomly selected" is weighted by the probability of the observers existing: under SIA you are still unlikely to be an unlikely observer, unless there are a lot of them.
For instance, if there is a coin flip that on heads will create one observer, while on tails they will create two, then we have three possible observers (1st observer on heads, 1st on tails, 2nd on tails), each existing with probability 0.5, so SIA assigns 1/3 probability to each. Alternately, this could be interpreted as saying there are two possible observer (1st observer, 2nd observer on tails), the first existing with probability one and the second existing with probability 1/2, so SIA assigns 2/3 to being the first observer and 1/3 to being the second - which is the same as the first interpretation.
This is why SIA gives an answer of 1/3 probability of heads in the Sleeping Beauty Problem
Sleeping Beauty problem
The Sleeping Beauty problem is a puzzle in probability theory and formal epistemology in which an ideally rational epistemic agent is to be wakened once or twice according to the toss of a coin, and asked her degree of belief for the coin having come up heads....
.
Notice that unlike SSA
Self-Sampling Assumption
The self-sampling assumption , one of the two major schools of anthropic probability , states that:...
, SIA is not dependent on the choice of reference class, as long as the reference class is large enough to contain all subjectively indistinguishable observers. If the reference class is large, SIA will make it more likely, but this is compensated by the much reduced probability that the agent will be that particular agent in the larger reference class.
Although this anthropic principle
Anthropic principle
In astrophysics and cosmology, the anthropic principle is the philosophical argument that observations of the physical Universe must be compatible with the conscious life that observes it. Some proponents of the argument reason that it explains why the Universe has the age and the fundamental...
was originally designed as a rebuttal
Self-Indication Assumption Doomsday argument rebuttal
The Self-Indication Assumption Doomsday argument rebuttal is an objection to the Doomsday argument by arguing that the chance of being born is not one, but is an increasing function of the number of people who will be born.- History :This objection to the Doomsday Argument ,...
to the Doomsday argument
Doomsday argument
The Doomsday argument is a probabilistic argument that claims to predict the number of future members of the human species given only an estimate of the total number of humans born so far...
(by Dennis Dieks
Dennis Dieks
Dennis Dieks is a Dutch physicist and philosopher of physics. In 1982 he proved the no-cloning theorem . In 1989 he proposed a new interpretation of quantum mechanics, later known as a version of the modal interpretation of quantum mechanics...
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
Quantum cosmology
In theoretical physics, quantum cosmology is a field attempting to study the effect of quantum mechanics on the formation of the universe, or its early evolution, especially just after the Big Bang...
.
Ken Olum has written in defense of the SIA. Nick Bostrom
Nick Bostrom
Nick Bostrom is a Swedish philosopher at the University of Oxford known for his work on existential risk and the anthropic principle. He holds a PhD from the London School of Economics...
and Milan Cirkovic have critiqued this defense.
See also
- Bayesian inferenceBayesian inferenceIn statistics, Bayesian inference is a method of statistical inference. It is often used in science and engineering to determine model parameters, make predictions about unknown variables, and to perform model selection...
- Self-Sampling AssumptionSelf-Sampling AssumptionThe self-sampling assumption , one of the two major schools of anthropic probability , states that:...
- Self-Indication Assumption Doomsday argument rebuttalSelf-Indication Assumption Doomsday argument rebuttalThe Self-Indication Assumption Doomsday argument rebuttal is an objection to the Doomsday argument by arguing that the chance of being born is not one, but is an increasing function of the number of people who will be born.- History :This objection to the Doomsday Argument ,...
- Anthropic principleAnthropic principleIn astrophysics and cosmology, the anthropic principle is the philosophical argument that observations of the physical Universe must be compatible with the conscious life that observes it. Some proponents of the argument reason that it explains why the Universe has the age and the fundamental...