Document Type
Article
Publication Date
9-2022
Keywords
Abiogenesis; astrobiology; carter argument; life in the universe
Abstract
The observation of life on Earth is commonly believed to be uninformative regarding the probability of abiogenesis on other Earth-like planets. This belief is based on the selection effect of our existence. We necessarily had to find ourselves on a planet where abiogenesis occurred, thus nothing can be inferred about the probability of abiogenesis from this observation alone. This argument was first formalized in a Bayesian framework by Brandon Carter. Though we definitely had to find ourselves on a planet where abiogenesis occurred, I argue here that (1) the Carter conclusion is based on what is known as the ‘Old Evidence Problem’ in Bayesian Confirmation Theory and that (2) taking this into account, the observation of life on Earth is not neutral but evidence that abiogenesis on Earth-like planets is relatively easy. I then give an independent timescale argument that quantifies the prior probabilities, leading to the inference that the timescale for abiogenesis is less than the planetary habitability timescale and therefore the occurrence of abiogenesis on Earth-like planets is not rare.
Citation
Whitmire, D. P. (2022). Abiogenesis: The Carter Argument Reconsidered. International Journal of Astrobiology, 22 (2), 94-99. https://doi.org/10.1017/S1473550422000350
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
