Our Order of Preachers was founded in a context of great religious turmoil, when heresies divided the Church and caused great harm to those who held to them.
Those preaching and adhering to these heresies were not lacking in zeal or in giving witness to their commitment to their way of life and so a fraternity of preaching brothers, voluntarily poor and obedient, proved to be the only way to convince the heretics of the falsehoods they had held. Dominican preaching is not only based upon appeals to the heart, however.
Our fraternal life appeals to that. But our preaching is based, unlike the heretics of the thirteenth century, on solid study of the faith and the consequences coming from it.