Otto Kirn (January 23, 1857 – August 18, 1911) was a German Lutheran theologian and university professor.
Kirn went through the Evangelical Seminaries of Maulbronn and Blaubeuren, where he was trained, among others, by the philosopher Karl Christian Planck.
with the work Die christliche Vollkommenheit (The Christian Perfection) and in 1889 he was finally promoted to Doctor of Philosophy and graduated with the dissertation Kants transcendentale Dialektik in ihrer Bedeutung für die Religionsphilosophie (Kant's Transcendental Dialectic in its Importance for the Philosophy of Religion).
There he began in 1889 as a Privatdozent for New Testament and systematic theology, in 1890 extraordinary and finally in 1894 full Professor of the University of Basel in this field.
In the latter work, Kirn criticized as overbroad Max Bernhard Weinstein's assertions that such historical philosophers as John Scotus Eriugena, Anselm of Canterbury, Nicholas of Cusa, Giordano Bruno, Moses Mendelssohn, and Gotthold Ephraim Lessing were pandeists or leaned towards pandeism.