He received his undergraduate degree in 1959 and was hired as an assistant at the University of Brussels, which is a faculty position in the Belgian system.

While working on his doctoral dissertation, which dealt with reaction times, Falmagne became interested in the applications of mathematics to the cognitive sciences.

He presented the results of his dissertation at a conference there and met several prominent mathematical psychologists, including Bill Estes, Dick Atkinson, and Duncan Luce, and the mathematician János Aczél.

Until 2013, Falmagne was Chairman of ALEKS Corporation, a web-based educational software company that he founded with some of his graduate students.

[DF85] In this article, they presented a formal framework for the assessment of knowledge in various academic subjects, such as arithmetic, algebra, and chemistry.

This early framework was combinatoric in character, and as such insufficient for a practical assessment, which is unavoidably plagued by careless errors on the part of the test takers.

Falmagne and Doignon's 2011 book, Learning Spaces,[FD11] contains the most current presentation and development of the stochastic framework for the assessment of knowledge.

More generally, these lines of research are collectively called Knowledge Space Theory and are being pursued by many investigators, mostly in Austria, Germany, and the Netherlands.

Two special issues of the Journal of Mathematical Psychology were published in 2005 with the papers presented at two meetings organized to honor his 70th birthday.