Children in  Malawi, Africa who lost their mother to Aids. Pope Paul VI wrote: “The development of peoples has the church’s close attention, particularly the development of those  striving to escape from hunger, misery, endemic diseases and ignorance.” Photograph: Brenda Fitzsimons

Of all the many papal encyclicals down the ages, it is arguable that the document known as Populorum Progressio, issued by Pope Paul VI 50 years ago o(...)