“If Kant ever betrayed a deep knowledge of human nature,
it was especially in his friendships.”
Jachmann [1804, 91-92]
[This page is a total work-in-progress]
A longer list of friends would include the following, whom I’ve grouped by occupation or social world, some appearing on more than one list. Those with an asterisk (*) also studied under Kant at the university; those with (TF) were a regular Tischfreund or dinner guest of Kant’s, and with an asterisk (TF*) are those who attended the first “Freunde Kant Gesellschaft” on 22 April 1805.
Theodor Michael Freytag taught at the Kneiphof school, then pastor in Neuhausen (1767).
Gave Kant free lodging after Wlömer left for Berlin (matriculated 2 May 1746: from “Kusso-Litthvan. Boruss.”).
French merchant and father-in-law to Robert Motherby; business partner with Jean Claude Lavel. Mellin [1804, 1: 149, 151] claimed that Toussaint was Kant’s closest friend – his only friend in the sense of a “moral friendship.”
Geheimen Commerzienrat. Married (1752) and divorced (1768) Charlotta Schwinck (below). Uncle and heir to Friedrich Conrad Jacobi (below).
Business partner with Robert Motherby.
Kommerzienrat und Negotianten.
Kant presumably made frequent visits to Hüge’s estate at Prilacken.
Born in Riga to a patrician family, studied law at the university in Königsberg (1748-51), matriculating 10 Aug 1748, which is when we think Kant left Königsberg to work as a Hofmeister, so the two might have become acquainted until after 1754, and in 1759 Johann Georg Hamann has dedicated his Socratische Denkwürdigkeiten (1759) to “den Zween” (i.e., Kant and Berens), whom Hamann compared to Socrates and Alcibiades. Apart from Berens’ work as a merchant, he had strong literary interests, editing the weekly periodical Daphne (1750), with contributions from Hamann.
Business partner with Joseph Green.
Munz-Meister, later Munz-Direktor.
French merchant and business partner with Jean Claude Toussaint.
Married (1752) and divorced (1768) Johann Conrad Jacobi. Married (c.1769) Johann Julius Göschen.
Scottish merchant and grandson of the merchant Francis Hay; directed the firm Barckley und Hay with his partner, the Englishman David Barckley (†1809). Barckley had married Elisabeth Henriette Dittrich (1774-1840), and Henriette along with Hay’s daughter, also named ‘Henriette’, maintained one of the leading salons of Königsberg, alongside those of Johanna Motherby and Elisabeth Stägemann [Gause 1996, 2: 303-4].
Nephew to Johann Conrad Jacobi (above) and heir of the business.
Arrived in Königsberg in 1782. Married (1804) Johanna Catharina Elisabeth Jacobi, daughter of Friedrich Conrad Jacobi (above).
Reichardt  briefly compares Kant and Hamann in his parallel sketches, and an early unsigned study of this relationship appeared serially in the Preußische Provinzial-Blätter (1853), pp. 164-73, 293-99, 385-96, 410-17.
Kriminalrat. Moved to Königsberg in 1784.
Son of Kant’s colleague, Prof. C. D Reusch (1735-1806); younger brother to Carl Wilhelm Georg Reusch. Geheimer Oberregierungsrat.
Stadtrat (replacing Jensch in 1802). Matriculated at the university on 18 Sep 1779. Son of Kant’s old rival, Professor F. J. Buck (1722-1786).
Full Prof. of Law
Full Prof. of Oriental Languages
Taught at the Cathedral school (1747), then pastor at Kirchdorf Neuhaussen (1767)[Vorländer 1924, 1: 88].
Full Prof. of Physics
Full Prof. of Poetry (1765). Likely knew Kant from their school days, as he attended the Coll. Fridericianum (1736-44) and the university (1744-48).
Full Prof. of Mathematics
Prof. of Medicine, later also of Physics
Full Prof. of Medicine
Assoc. Prof. of Philosophy, later Full Prof. of Poetry, Pedagogy, History, Practical Philosophy.
Full Prof. of Practical Philosophy
Full Prof. of Oriental Languages
Assoc. Prof. of Mathematics
Lecturer in Philosophy
Inspector of the Poor Schools.
Son of Johann Georg Hamann. Rector of the Altstadt Gymnasium.
Assoc. Prof. of Oriental Languages, Full Prof. of Theology
Son of Kant’s colleague, Prof. C. D Reusch (1735-1806); older brother to Christian Friedrich Reusch.
Student 1766-70, then moved to Berlin.
Director, Pedagogy Institute (Jenkau bei Danzig).
Head forester at Moditten, where Kant would visit him.
Bookdealer and Kant’s publisher (after 1790).
Reusch [1848b, 299] provides a list of everyone who attended the first “Friends of Kant Society” birthday celebration that took place in Kant’s home and was arranged by the physician William Motherby. These were all the people who had been invited to his last birthday party (22 April 1803) described by Wasianski [1804, 142-43].
“Professoren Kraus, Pörschke, Hasse, Hagen Med. R., Gensichen, Kriegsrath Scheffner, Reg. R. Vigilantions, Reg. R. a. D. Schreiber, Bürgermeister Buck, Pfarrer Wasianski, Pfarrer Sommer, Dr. med Jachmann, Ober-Stadt-Inspector Brahl, Buchhändler Nicolovius, Kaufmann Joh. Reinhold Jacobi und Gädecke, John Motherby, Criminal-Räthe Stägemann und Frey, die Doctoren der Medizin William Motherby, Laubmeyer, [Carl Wilh. Georg] Reusch, [Christoph Fr.] Elsner, Director [Joh. Mich.] Hamann, Reg. Assessor [Christian Fr. Reusch.”
“Prediger Wannowski, Regierungsrath Schulz, Reg. und Schulrath Jachmann.”
Everyone in the Reusch list is accounted for in the lists above, except for “Kaufmann Joh. Reinhold Jacobi”. I've been unable to identify anyone with this name and so have to assume that it was written in error; the intended reference is almost certainly Friedrich Conrad Jacobi (1752-1816), nephew and heir to Johann Conrad Jacobi (1717-1774) and the business partner and father-in-law to Johann Christian Gädeke (1765-1853), the next name in the list.
[Kant discussed friendship in his ethics lectures (the last section of Baumgarten’s Philosophical Ethics concerned “duties regarding friends and friendlessness”)[see Moral Herder, 27:50, 54; Moral Collins (27:358, 419-20, 422-30 + the next section on Enmity); Moral Vigilantius (27:675-86 + following section on enmity], and wrote on it in his Metaphysics of Morals