How advanced can civilizations reasonably get before the use

>>55319095
Plastics were invented in 1862 so victorian era

you could have a futuristic space faring civilization without plastic or computers.

>>>/dune/

(yes i realize dune has plastic)

>>55319191
However, in the case of Dune, they had advanced computers in the past and have purposely created/trained human counterparts to fill in the roles that advanced computers once had. Also, while advanced computers were banded, they still used some computer systems (controlling the systems on the no-ships for an exaple). Just nothing that could think or process a large amount of data at once.