Estadista y uno de los primeros diplomáticos brasileños.Se cuenta entre los once hermanos de Bartolomé de Gusmão , conocido como el padre volador por haber creado el primer aerostato en 1709. Estudió Derecho en la tradicional Universidad de Coimbra (Portugal), donde destacó en materias como Latín, Lógica, Metafísica, Ética, Retórica y Filosofia. En la corte de Juan V sobresalió gracias a su actuación en la negociación con España del Tratado de Madrid : defendió los límites del territorio colonial de Brasil con la América Española y asesoró al Conde de Vila Nova de Cerveira. Se le atribuyó la utilización del principio de derecho romano <i>uti possidetis,</i> según el cual cada soberanía tenía derecho a las tierras que físicamente ocupaba. Este principio guió la negociación del tratado y pudo ser precursor de la aplicación de los principios de la Ilustración en las relaciones internacionales.
Abstract from English Wikipedia: <blockquote>"Alexandre de Gusmão (Santos, 17 July 1695 - Lisbon, 9 May 1753) was a diplomat born in the Portuguese colony of Brazil. He is regarded as one of the best diplomats of his time, chiefly for his role in negotiating the Treaty of Madrid in 1750 (revoked in 1761), when Portugal and Spain were attempting to delimit their territorial possessions in South America and Asia. Born in the city of Santos, he may be considered one of the precursors of the application of the principles of Illuminism to international relations, adopting the principle of uti possidetis, according to which each state has the right to the land that it actually occupies, as well as the idea of "natural boundaries", which suggests the use of prominent geographical accidents - such as rivers and mountain ranges - to set the limits between states. He graduated in Law and was the representative of Portugal to various states, among which Rome, where he came to be invited to join Pope Innocent XIII's court. He was also a brother of Bartolomeu de Gusmão, a priest and naturalist recalled for his early work on lighter-than-air airship design (balloons)."</blockquote>