Reinhold was born in Vienna. At the age of fourteen he entered the Jesuit college of St. Anna, on the dissolution of which (1773) he joined a similar college of the order of St. Barnabas. Finding himself out of sympathy with monastic life, he fled in 1783 to North Germany, and settled in Weimar, where he became Christoph Martin Wieland's collaborator on the German Mercury (Der Teutsche Merkur), and eventually his son-in-law.

In the German Mercury he published, in the years 1786 - 87, his Briefe über die Kantische Philosophie (Letters on the Kantian Philosophy), which were most important in making Kant known to a wider circle of readers. As a result of these Letters, Reinhold received a call to theUniversity of Jena, where he taught from 1787 to 1794.

In 1789 he published his chief work, the Versuch einer neuen Theorie des menschlichen Vorstellungsvermögens (Essay towards a New Theory of the Faculty of Representation), in which he attempted to simplify the Kantian theory and make it more of a unity by basing it on one principle, Reinhold's Principle of Consciousness. In 1794 he accepted a call to Kiel, where he taught till his death in 1823, although his independent activity had come to an end.

In later life he was powerfully influenced by Fichte, and subsequently, on grounds of religious feeling, by F.H. Jacobi and Bardili. His historical importance belongs entirely to his earlier activity. The development of the Kantian standpoint contained in the New Theory of Human Understanding (1789), and in the Fundament des philosophischen Wissens (1791), was called by its author Elementärphilosophie.

"Reinhold lays greater emphasis than Kant upon the unity and activity of consciousness. The principle of consciousness tells us that every idea is related both to an object and a subject, and is partly to be distinguished from and partly united to both. Since form cannot produce matter and a subject cannot produce an object, we are forced to assume a thing-in-itself. This is a notion which is self-contradictory if consciousness were to be essentially a relating activity. There is therefore something which must be thought and yet cannot be thought."

As a former Catholic priest, Reinhold retained the values of Christian morality and individual dignity. The basic Christian doctrines of a transcendent God and an immortal human soul were presuppositions in his thinking. However, he disagreed with Friedrich Heinrich Jacobi, who thought that the only way to avoid nihilism, fatalism, and atheism was to believe in the religious morality that was revealed by God. Reinhold tried to show that Kant's philosophy provided an alternative to either religious revelation or philosophical skepticism and fatalistic pantheism. But Kant's Critique of Pure Reason was a difficult and confusing book. It was not widely read and had little influence. Reinhold decided to write his comments on it in the literary journal The German Mercury. He skipped over the beginning and middle of the book and started at the end. Reinhold showed that the book was best read backwards, that is, starting with the end section. The last part of the Critique is where Kant discussed the issues of morality and their relation to the Rational Ideas of God, Free Will, and life after death. These issues were Reinhold's main concern. By presenting these concerns to the public, instead of the extremely difficult epistemology that took up most of the beginning and middle of the book, Reinhold aroused great interest. As a result, Kant's Critique immediately became a book of great importance.

According to editor Karl Ameriks, "...Fichte, Hegel, Schelling, Schiller, Hölderlin, Novalis, and Friedrich Schlegel all developed their thought in reaction to Reinhold's reading of Kant...." There is a Faustian tendency in Reinhold's assertion that a person can hope for a future reward only because that person is constantly striving to be good. It is not moral to be good merely in the hope of reward. Reinhold's emphasis on history is evident in his declaration that philosophies and religions are to be judged on the way that they respond to the needs of reason in a particular era. Philosophical development, to him, has an underlying rationality. New philosophies are fated to struggle repeatedly in order to survive in a dialectic of history in which progress is unconsciously occurring. With regard to a transcendent God, the human internal moral law is externalized in such a deity. This extreme otherness or alienation is part of a rational process. It makes possible a subsequent deeper regaining of the self through something other than the self.

Kant's critical philosophy was not being accepted as the final truth. According to Professor George di Giovanni, of McGill University, Reinhold tried to provide a foundation for Kant's philosophy in order to remedy this situation. Reinhold distinguished two levels of philosophy. The most basic level was the concern with consciousness and the representations that occurred in it. The second, less basic, level, was the concern with the possibility and structure of the known or desired objects.

Kant's important realization was that the possibility of metaphysics can be established. This can be done only by describing what occurs when the mind is conscious of objects. Kant's weakness was in being overly concerned with the objects themselves. He remained at the second, less basic, level of philosophy. He rarely examined what occurred in consciousness, which is the basic level of philosophy. Kant did not provide a phenomenological description of consciousness. Reinhold was convinced that Kant should have identified the fundamental fact of consciousness that was essential in making cognition itself possible.

Reinhold's Essay towards a New Theory of the Human Faculty of Representation is a description of the main parts and attributes of consciousness. In writing this book, Reinhold turned his attention from the moral issues that Kant addressed in the end section of his Critique of Pure Reason to the epistemological concerns of the beginning and middle sections.