Although praised by Noam Chomsky and others on the Left for his tireless opposition to the 2003 invasion of Iraq and ongoing US policies in the Middle East and Persian Gulf, Roberts' criticisms of neoconservatism and its influence over foreign policy seem to stem from deeper philosophical differences with the ideas of Leo Strauss, who many regard as the founder of the new Right's ideology. Roberts contends that Strauss is guilty of a fundamental and possibly willful misreading of Plato that stems from using al-Farabi's Commentary rather than the Socratic texts. He also places Strauss within the context of Nietzsche, Adorno, Heidegger and other exponents of what he terms "philosophical fascism".

Roberts has been a long-time friend of the writers Martin Amis, with whom he shared a house at Oxford, and Christopher Hitchens. Roberts now refers to the latter as an "apostate" from the Left and a "deluded opportunist", and the status of their friendship is unclear.

Roberts was for many years a supporter of Israel but he has increasingly criticized Israeli policies and expressed sympathy for the plight of Palestinians, stating that he now views them as "more sinned against than sinning".