pseudo-rational
/ˌs(j)uːdə(ʊ)ˈraʃ(ə)n(ə)l/ /ˌs(j)uːdə(ʊ)ˈraʃən(ə)l/adjective
Supposed or purporting to be rational; giving the illusion of rationality; apparently rational but not really so.
Origin
Late 19th century; earliest use found in The Contemporary Review. From pseudo- + rational.