Kraft disputes La Mettrie's claim that the connection between thought and the body implies a causal relationship. He acknowledges that rational beings have larger brains than irrational ones and that thought is influenced by bodily conditions, illnesses, and emotions. However, he maintains that these observations only demonstrate a connection, not causation.

Kraft distinguishes between time and eternity, arguing that while the finite can never attain eternity, it can achieve an infinite time with a beginning but no end. He contrasts this with the permanence of the infinite.

Jens Kraft (1720–1765) was a Dano-Norwegian mathematician and philosopher. He was born in Frederikshald in Norway.
While still a student in Copenhagen, he was influenced by Christian Wolff, having attended one of Wolff’s lectures during a visit to Halle. Later he was appointed professor of philosophy at the Sorø Academy, where he responded to Baumgarten’s Metaphysica with his own work, Metaphysik. Both philosophers structured their works into four divisions: Cosmologie, Ontologie, Psykologie, and Naturlig Theologie.