People holding this position believe that there is life of some form located on some other planents
People holding the belief that life does not exist elsewhere in the universe.
The belief that life is able to naturally spread throughout the Solar System and Galaxy
The belief that humanity has accidentally contaminated other planets with life by sending rovers and landers to their surface that were not sufficiently decontaminated
This is the belief that life is likely to have developed elsehwere in the usiverse completely independntly of other life
Similar to the argument of the development of Simple life, but with the added step of the life becoming complex and potentially intellignet