I've found a reference in a Jewish text from the mid-19th century to a "gentile sage" (an expression usually referring to a Greek philosopher, but it could be any non-Jewish person really) who said that an assembly or parliament which was elected without any opposition is not fit for purpose and should be dissolved, because an opposition is vital to sound decision-taking. Can anyone give me any clue as to who might have said this? Thanks!
Not exactly what you ask but close if you treat cannot be secure as the flip of should be dissolved
No government can be long secure without a formidable opposition
Dunno about 'gentile sage' but Disraeli was a 19th century English PM of Jewish descent, though his father left Judaism.