Encyclopedia of Opinion
Question
Do aliens exist?
Position3 of 4
Probably, but we don’t yet have proof of alien life
Argument1 of 2

Several exoplanets have been discovered that may harbor alien life

The so-called exoplanets are planet found outside our Solar System. Some might be candidate for a life

The argument

The analysis in the latest years allows detecting planets on outer Solar Systems. The analysis could predict the composition of the planet (spectrography), whether it is a gas giant (such as Jupiter and Saturn) or a rocky planet; and its orbit around the sun. For example, if the orbits are inside what is called "Goldilocks" zone where water on the liquid state can exist.

Context

The advance in space exploration with telescopes or other instruments either on Earth or in Space allowed the detection of several planets on many Stars.

Premises

[P1]Modern analysis can detect planets in other solar systems and use spectrography to predict their composition, whether they are gas giants or rocky, and their orbits. [P2] Some detected exoplanets sit in the 'Goldilocks' zone where liquid water can exist, a key condition for life. [C] Because several such exoplanets may harbour life, alien life probably exists even though we don't yet have proof.

Counter-arguments

The analysis conducted so far only proves that some planets might be compatible with life but does not say anything with respect of actual presence of a life-form or which is its state (whether primordial or intelligent).

Rejecting the premises

[Rejecting P1] The detection methods described establish far less than the premise implies: transit and radial-velocity data yield size, mass and orbit, and atmospheric spectroscopy has so far been achieved for a small number of mostly large, hot planets — so "predicting composition" overstates what is currently measurable for rocky worlds. [Rejecting P2] The habitable zone is defined by the possibility of surface liquid water given a suitable atmosphere, which is a screening criterion rather than a finding about a planet — a world in that zone may be airless, tidally locked or dry, so counting such planets supports the claim that suitable locations are common, not that any of them harbours life.

Further reading

Nasa site on exoplanets exploration: https://exoplanets.nasa.gov