放荡主义或荡放主义指活跃于17世纪的欧洲（英法两国为主）之政治和社会群体。放荡主义者指脱离社会和宗教的正常观念和道德束缚的人。

放荡主义是一种自由思想哲学；首先用于指称一个于16世纪的荷兰，反抗既有传统的再洗礼派别。要注意的这“自由思想”指反对既有传统、信念、权威和信仰的哲学。其在18世纪和世纪的英格兰和法国得到新支持者，代表人物有萨德侯爵和艾利斯特·克劳利。现时放荡主义相关于施虐与受虐、虚无主义和不限于与一长期伴侣的爱情和开放式关系。

1782年出版的《危险关系》鲜明地以性为题表达了放荡主义。

在现代，这个词通常用于那些在不通礼教，在道德方面上过度潇洒的人身上。

A libertine is one devoid of most moral or sexual restraints, which are seen as unnecessary or undesirable, especially one who ignores or even spurns accepted morals and forms of behaviour sanctified by the larger society. Libertinism is described as extreme form of hedonism. Libertines put value on physical pleasures, meaning those experienced through the senses. As a philosophy, libertinism gained new-found adherents in the 17th, 18th, and 19th centuries, particularly in France and Great Britain. Notable among these were John Wilmot, 2nd Earl of Rochester, and the Marquis de Sade.