I'm sure there is a 'rational' [='sensible, reasonable'] explanation for his decision.
Humans are 'rational' beings. [=are able to use reason when thinking about something]
No 'rational' [='sane'] person would behave like that.
(..) I don't understand, exactly how did he get any friends in the first place? We liked Leonard. What are you gonna do, just give up? Yes, it's what a rational person does when his entire life's work is invalidated... ...by a postpubescent Asian wunderkind. He ceases his fruitless efforts, (..)2008 TvShow: The Big Bang Theory Title: The Jerusalem Duality Season: 1 Episode 12