No other thinker of modern times has been throughout his work so
penetrated with the fundamental conceptions of physical science; no
other has been able to hold with such firmness the balance between
empirical and speculative ideas. Beyond all question much of the
influence which the critical philosophy has exercised and continues to
exercise must be ascribed to this characteristic feature in the
training of its great author.
The early writings of Kant are almost without exception on questions
of physical science. It was only by degrees that philosophical
problems began to engage his attention, and that the main portion of
his literary activity was turned towards them. The following are the
most important of the works which bear directly on physical science.
1. _Gedanken von der wahren Schatzung der lebendigen Krafte_ (1747);
an essay dealing with the famous dispute between the Cartesians and
Leibnitzians regarding the expression for the _amount of a force_.
According to the Cartesians, this quantity was directly proportional
to velocity; according to their opponents, it varied with the square
of the velocity. The dispute has now lost its interest, for physicists
have learned to distinguish accurately the two quantities which are
vaguely included under the expression _amount of force_, and
consequently have been able to show in what each party was correct and
in what it was in error. Kant's essay, with some fallacious
explanations and divisions, criticizes acutely the arguments of the
Leibnitzians, and concludes with an attempt to show that both modes of
expression are correct when correctly limited and interpreted.
2. _Whether the Earth in its Revolution has experienced some Change
since the Earliest Times_ (1754; ed. and trans., W. Hastie, 1900,
_Kant's Cosmogony_; cf. Lord Kelvin in _The Age of the Earth_, 1897,
p. 7). In this brief essay Kant throws out a notion which has since
been carried out, in ignorance of Kant's priority, by Delaunay (1865)
and Adams. He points out that the action of the moon in raising the
waters of the earth must have a secondary effect in the slight
retardation of the earth's motion, and refers to a similar cause the
fact that the moon turns always the same face to the earth.
3. _Allgemeine Naturgeschichte und Theorie des Himmels_, published
anonymously in 1755 (4th ed. 1808; republished H. Ebert, 1890). In
this remarkable work Kant, proceeding from the Newtonian conception of
the solar system, extends his consideration to the entire sidereal
system, points out how the whole may be mechanically regarded, and
throws out the important speculation which has since received the
title of the nebular hypothesis. In some details, such e.g. as the
regarding of the motion of the entire solar system as portion of the
general cosmical mechanism, he had predecessors, among others Thomas
Wright of Durham, but the work as a whole contains a wonderfully acute
anticipation of much that was afterwards carried out by Herschel and
Laplace. The hypothesis of the original nebular condition of the
system, with the consequent explanation of the great phenomena of
planetary formations and movements of the satellites and rings, is
unquestionably to be assigned to Kant. (On this question see
discussion in W. Hastie's _Kant's Cosmogony_, as above.)
4. _Meditalionum quarundam de igne succincta delineatio_ (1755): an
inaugural dissertation, containing little beyond the notion that
bodies operate on one another through the medium of a uniformly
diffused, elastic and subtle matter (ether) which is the underlying
substance of heat and light. Both heat and light are regarded as
vibrations of this diffused ether.
5. _On the Causes of Earthquakes_ (1755); _Description of the
Earthquake of 1755_ (1756); _Consideration of some Recently
Experienced Earthquakes_ (1756).
6. _Explanatory Remarks on the Theory of the Winds_ (1756). In this
brief tract, Kant, apparently in entire ignorance of the explanation
given in 1735 by Hadley, points out how the varying velocity of
rotation of the successive zones of the earth's surface furnishes a
key to the phenomena of periodic winds. His theory is in almost entire
agreement with that now received. See the parallel statements from
Kant's tract and Dove's essay on the influence of the rotation of the
earth on the flow of its atmosphere (1835), given in Zollner's work,
_Ueber die Natur der Cometen_, pp. 477-482.
7. _On the Different Races of Men_ (1775); _Determination of the
Notion of a Human Race_ (1785); _Conjectural Beginning of Human
History_ (1786): three tracts containing some points of interest as
regards the empirical grounds for Kant's doctrine of teleology.
Reference will be made to them in the notice of the _Kritik of
Judgment_.
8. _On the Volcanoes in the Moon_ (1785); _On the Influence of the
Moon on the Weather_ (1794). The second of these contains a remarkable
discussion of the relation between the centre of the moon's figure and
its centre of gravity. From the difference between these Kant is led
to conjecture that the climatic conditions of the side of the moon
turned from us must be altogether unlike those of the face presented
to us. His views have been restated by Hansen.
9. _Lectures on Physical Geography_ (1822): published from notes of
Kant's lectures, with the approval of the author.
Consideration of these works is sufficient to show that Kant's mastery
of the science of his time was complete and thorough, and that his
philosophy is to be dealt with as having throughout a reference to
general scientific conceptions. For more detailed treatment of his
importance in science, reference may be made to Zollner's essay on
"Kant and his Merits on Natural Science" contained in the work on the
_Nature of Comets_ (pp. 426-484); to Dietrich, _Kant and Newton_;
Schultze, _Kant and Darwin_; Reuschle's careful analysis of the
scientific works in the _Deutsche Vierteljahrs-Schrift_ (1868); W.
Hastie's introduction to _Kant's Cosmogony_ (1900), which summarizes
criticism to that date; and articles in _Kant-Studien_ (1896 foll.).
The notice of the philosophical writings of Kant need not be more than
bibliographical, as in the account of his philosophy it will be
necessary to consider at some length the successive stages in the
development of his thought. Arranged chronologically these works are
as follows:--
1755. _Principiorum primorum cognitionis metaphysicae novae
dilucidatio._
1756. _Metaphysicae cum geometria junctae usus in philosophia
naturali, cujus specimen I. continet monadologiam physicam._
1762. _Die falsche Spitzfindigkeit der vier syllogistischen Figuren_,
"The False Subtlety of the Four Syllogistic Figures" (trans. T. K.
Abbott, _Kant's Introduction to Logic and his Essay on the Mistaken
Subtilty of the Figures_, 1885).
1763. _Versuch den Begriff der negativen Grossen in die Weltweisheit
einzufuhren_, "Attempt to introduce the Notion of Negative Quantities
into Philosophy."
1763. _Der einzig mogliche Beweisgrund zu einer Demonstration des
Daseins Gottes_, "The only possible Foundation for a Demonstration of
the Existence of God."
1764. _Beobachtungen uber das Gefuhl des Schonen und Erhabenen_ (Riga,
1771; Konigsberg, 1776).
1764. _Untersuchung uber die Deutlichkeit der Grundsatze der
naturlichen Theologie und Moral_, "Essay on the Evidence (Clearness)
of the Fundamental Propositions of Natural Theology and Ethics."
1766. _Traume eines Geistersehers, erlautert durch Traume der
Metaphysik_, "Dreams of a Ghost-seer (or Clairvoyant), explained by
the Dreams of Metaphysic" (Eng. trans. E. F. Goerwitz, with introd. by
F. Sewall, 1900).
1768. _Von dem ersten Grunde des Unterschiedes der Gegenden im Raum_,
"Foundation for the Distinction of Positions in Space."
The above may all be regarded as belonging to the precritical period
of Kant's development. The following introduce the notions and
principles characteristic of the critical philosophy.