In 1965, Maurice Lagueux completed a doctorate in philosophy at the University of Paris, under the direction of Paul Ricœur, with a thesis entitled "Merleau-Ponty et la tâche du philosophe". The same year he was hired by the Department of Philosophy at the Université de Montréal to teach mainly courses in philosophy of history, which he did regularly until his retirement in 2005.
Between 1968 and 1970, he was granted a teaching leave which allowed him to obtain a master's degree in economics at McGill University, where he wrote a thesis on the theme of Externality and Property. From 1970 onwards, the epistemology of economics thus became one of his privileged fields of research, in addition to the philosophy of history considered in both the analytic and continental traditions. Since then, his courses at the Department of Philosophy have also dealt with questions related to these two fields.
In keeping with this interest in history and economics, he has also taught the epistemology of the social sciences and was led to study the work of Karl Marx. He devoted a teaching to this author’s thought, both at the Université de Montréal and at the University of Ottawa's Department of Philosophy, where he was a three-quarter-time invited professor in 1976-77. In 1982, he published Le marxisme des années soixante, for which he received the Governor General's Award in the "Essays" section. That same year he was promoted to full professor in the Department of Philosophy at the Université de Montréal, and in 1982-83 he served as President of the Canadian Philosophical Association. Since 1978, he has given part of his teaching load to the Department of Economics at the Université de Montréal, thanks to an interdepartmental agreement. It is within this framework that he taught the course on the history of economic thought in this department for over twenty years.
Having discovered a real passion for architecture in the mid-1980s, he made the philosophy of architecture a third field of research from the 1990s onwards, alongside the epistemology of economics and the philosophy of history. He published various articles in these three fields and, in 2001, a book entitled Actualité de la philosophie de l'histoire.
Retired from teaching since 2005, but remaining for several years an associate professor in the Department of Philosophy at the Université de Montréal, he has continued his research mainly in the epistemology of economics and the philosophy of architecture. In the first field, he published in 2010 a book entitled Rationality and Explanation in Economics and, in the second, he engaged in research on the architecture of universities which resulted in a book entitled Lieux de savoir, les campus universitaires et collégiaux. In the same period of time, he published a philosophical reflection of a quite different kind in a book entitled Tout en même temps agnostique et croyant.