His philosophy is a mixture of assent to and dissent from Descartes, the French and English sensists, Kant, and the Scottish school of Thomas Reid.

He maintained the objective reality of knowledge, which he based on the testimony of consciousness, making humans aware not only of their internal experience, but also of the external causes to which it is due.

Against the sensists, he denied that the mind was merely passive or receptive, and held that like a builder it arranged and ordered the materials supplied it, deducing therefrom new truths which sensation alone could never reach.

It was also natural that Galluppi should be foremost in attacking the theories of Rosmini concerning the idea of God as the first object of human knowledge: and it was this polemic (quiet enough in itself) which drew public attention to the Roveretan philosopher.

He always kept aloof from political questions; and his works were planned and written in his own home, amidst the noise and bustle of a large and happy family.