He studied in Naples, and in November 1922 obtained a degree in philosophy, his thesis that became the subject of his first book Le sorgenti irrazionali del pensiero (1923).

He died on 9 September 1990, and was buried in the cemetery of Santa Margherita Ligure, the Riviera town where he had spent his vacations for many years.

After moving to Turin, Abbagnano turned to the study of existentialism, which by this time was also the interest of the general Italian philosophical culture.

He formulated an original version of existentialism in his widely recognized book, La struttura dell'esistenza (1939), which was followed by his Introduzione all'esistenzialismo (1942) and a set of essays collected in Filosofia religione scienza (1947) and by Esistenzialismo positivo (1948).

In 1943, he played a very important part in the debate on existentialism that appeared in Primato, the review of the fascist opposition led by Giuseppe Bottai.

In existentialism, having freed himself from the negative implications he found in Heidegger, in Jaspers, in Sartre, in Dewey's pragmatism and in neopositivism, Abagnano saw the signs of a new philosophical trend, that he called a "New Enlightenment" in an article written in 1948.

The development of this idea in the fifties was precisely characterized both by his interest in science, in particular, sociology, and by an attempt to define the program of a philosophy, that he first called a "New Enlightenment" and later a "methodological empirism".