Within a few years of the publication of his Critique of Pure Reason in 1781, Immanuel Kant (1724–1804) was recognized by his contemporaries as one of the seminal philosophers of modern times – indeed as one of the great philosophers of all time. This renown soon spread beyond German-speaking lands, and translations of Kant's work into English were published even before 1800. Since then, interpretations of Kant's views have come and gone and loyalty to his positions has waxed and waned, but his importance has not diminished. Generations of scholars have devoted their efforts to producing reliable translations of Kant into English as well as into other languages.

There are four main reasons for the present edition of Kant's writings:

1. Completeness. Although most of the works published in Kant's lifetime have been translated before, the most important ones more than once, only fragments of Kant's many important unpublished works have ever been translated. These include the Opus postumum, Kant's unfinished magnum opus on the transition from philosophy to physics; transcriptions of his classroom lectures; his correspondence; and his marginalia and other notes. One aim of this edition is to make a comprehensive sampling of these materials available in English for the first time.

2. Availability. Many English translations of Kant's works, especially those that have not individually played a large role in the subsequent development of philosophy, have long been inaccessible or out of print. Many of them, however, are crucial for the understanding of Kant's philosophical development, and the absence of some from English-language bibliographies may be responsible for erroneous or blinkered traditional interpretations of his doctrines by English-speaking philosophers.

3. Organization. Another aim of the present edition is to make all Kant's published work, both major and minor, available in comprehensive volumes organized both chronologically and topically, so as to facilitate the serious study of his philosophy by English-speaking readers.

4. Consistency of translation. Although many of Kant's major works have been translated by the most distinguished scholars of their day, some of these translations are now dated, and there is considerable terminological disparity among them. Our aim has been to enlist some of the most accomplished Kant scholars and translators to produce new translations, freeing readers from both the philosophical and literary preconceptions of previous generations and allowing them to approach texts, as far as possible, with the same directness as present-day readers of the German or Latin originals.

Given the plethora of units in the German-speaking part of Europe in Kant's day, it is difficult to ascertain exactly which reference standard he was using on any given occasion. We may assume, however, that for the most part he used Prussian measures.

As Kant explains in § 8 of the Physical Geography, one ‘geographical mile’ was taken as 1/15 of a degree, measured along the Earth's circumference. Therefore there are 15 × 360 = 5,400 ‘geographical miles’ in the circumference of the Earth. Taking the modern value of 7,927 English miles for the equatorial diameter of the Earth, a geographical mile is thus 4.612 English miles. This figure may be used for the purposes of comparing Kant's astronomical data with modern measurements, as is done in Appendix ii. (It will be noted that good agreement is found for the diameter of the earth, which shows that the conversion factor of 4.612 is appropriate.) Also, since 7,927 is a known modern value, we may use it to gauge the value of the eighteenth-century units of length employed by Kant, even though we may not know exactly which standard he was referring to at any particular point in his text.It may be noted, however, that according to Ronald Zupko one Rhineland foot (as used in Prussia) was equal to 12.36 English inches (or 1.030 English feet). We have, therefore, a small discrepancy, but the information is adequate to gain a reasonably accurate estimate of which standard of length Kant was using.