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title: "Carl Sagan on The fine-tuning argument"
description: "Sagan questioned the assumptions underlying fine-tuning and argued that the universe's hostility to life undermines the design inference."
canonical: https://opendoubt.com/people/carl-sagan/on/fine-tuning
source: html
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# Carl Sagan on The fine-tuning argument

> Sagan questioned the assumptions underlying fine-tuning and argued that the universe's hostility to life undermines the design inference.

Position

# Carl Sagan on _The fine-tuning argument_

Argues againstAstronomer and science communicator

Sagan questioned the assumptions underlying fine-tuning and argued that the universe's hostility to life undermines the design inference.

Sagan did not engage with the fine-tuning argument in its modern technical form, which gained prominence in physics after his most active period. But his broader arguments about the cosmos are directly relevant. He consistently emphasised that the universe is overwhelmingly hostile to life — a point that cuts against any claim that it was designed with life in mind.

The famous 'pale blue dot' image, which Sagan championed, captures his perspective. Earth, seen from the edge of the solar system, is a barely visible speck. The universe extends for billions of light-years in every direction, almost all of it lethal to life. If the constants were fine-tuned for life, the tuner had remarkably poor aim.

Sagan would also have been sceptical of the probability claims underlying the argument. As a scientist, he understood that calculating the probability of physical constants requires knowing the space of possible values — information we do not have. Without it, claims about the improbability of our universe are not scientific conclusions but expressions of surprise dressed up as mathematics.

Key quotes

> “Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives.”

Continue exploring

[

Carl Sagan

Full profile — positions, quotes, and key moments.

](/people/carl-sagan)[

The fine-tuning argument

The full argument — stated fairly, then answered.

](/arguments/fine-tuning)

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