Three reasons lay behind the need for permanent deacons.
1) A desire to enrich the Church with the functions of the diaconate, which otherwise, in many regions, could only be exercised with great difficulty;
2) The intention of strengthening with the grace of diaconal ordination those who already exercised many of the functions of the Diaconate;
3) A concern to provide regions, where there was a shortage of clergy, with sacred ministers.
The word “Deacon” comes from the Greek diakonos, meaning “service”. In essence, deacons are ordained as servants of the church, which in itself reflects the spirituality of service, which is the spirituality of the whole Church.
“Only those are to be promoted to orders who ...have sound faith,
are motivated by the right intention, are endowed with the requisite knowledge,
enjoy a good reputation, and have moral probity, proven virtue and the other physical
and psychological qualities appropriate to the order to be received”.
Reference from the website of the Vatican: Basic norms for the formation of permanent deacons