He has a keen interest in political philosophy, and his philosophical outlook is influenced by Karl Popper, John Stuart Mill, Cesare Beccaria, Thomas Paine, Amartya Sen and Martha Nussbaum.

Liberales reacts against what it calls "narrow minded conservatism" related to social economic, ecological and ethical issues supported by "compartmentalized" parties and structures.

He wrote the books Pleidooi voor het individualisme (A Plea for Individualism) and De derde feministische golf (The Third Feminist Wave), much of it focusing on Islamic feminism and its impact in Europe.

In this book, he examines the position of Pacelli, the later Pius XII, towards Adolf Hitler’s seizure of power, the downfall of the Catholic Zentrumspartei, the Reichskonkordat between Nazi-Germany and the Vatican, the encyclical Mit brennender Sorge (With Burning Concern), paganism, the Nazist education programs, the ‘T4-program’ (the murder of physically and mentally handicapped persons), the invasion of Poland, Operation Barbarossa, the Jews in the Netherlands, priest-president Jozef Tiso of Slovakia, the Ustasha in Independent State of Croatia, the deportation of Jews from Rome, the Hungarian Holocaust, the help offered to war criminals, the resistance against Nazism, the alleged refusal of the Church to "give back Jewish" children who had been in hiding, the failures of the Allies, alleged antisemitism after the Holocaust, and the moral question of alleged guilt of the Church and the pope.

A scar that never goes away with Henri Heimans as co-author, about two people who survived the concentration camps Ravensbrück, Auschwitz, Mauthausen and Ebensee.