and evolutionary socialism After graduating in Medicine in 1871, he enrolled as a physician on a ship to South America before returning to Italy to devote himself to the study of sociology and continue his political activities. He returned to his home town, Castrogiovanni, where he practiced medicine and managed some sulfur mines owned by his mother. In 1875, Colajanni was among the participants at the Republican Congress in Rome to revive the movement. He started to collaborate with the magazine La rivista repubblicana of Arcangelo Ghisleri, which put him in contact with the exponents of republicanism and socialism in Milan. Through these democratic groups Colajanni came into contact with the positivist theories, and personalities such as Filippo Turati and Leonida Bissolati. Colajanni became one of the protagonists of the Italian positivist and evolutionary socialism, inspired by Darwinian evolution. With his book Il socialismo, published in 1884 in Catania, he became one of the first theoreticians of the Italian workers movement. His socialism was not based on the scientific Marxist approach, but was closer to the ideology of Mazzini – one of the fathers of Italian unification – with some influence of French utopian thinkers such as Georges Sorel, and in terms of practical politics resulted in a kind of radical-democratic reformism. In 1892 he was appointed Professor of Statistics at the University of Palermo. Since 1896 he directed the Rivista popolare, by means of which he strove to improve the moral and intellectual standard of the masses and combated all forms of intolerance and hypocrisy. Criminal sociology He published many books and essays on social and political problems, and exposed the unscientific theories of Cesare Lombroso and his Scuola positiva (Positive school) and Enrico Ferri on criminology. Colajanni was particularly critical of Lombroso's biological determinism – in particular the alleged inferiority of southern Italians – and he put a much greater emphasis on social conditions as a cause of offending. Lombroso and his disciples, however, remained dominant in Italy. Colajanni was the first to publish a book with criminal sociology in the title. He belonged to the Terza scuola (Third School) and argued that in order to curtail the level of crime in a society there should be a certain level of security with regard to sustainable living conditions, economic stability and a more equal welfare distribution. After the publication of his two-volume study La sociologia criminale in 1889,