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Immanuel Kant
(22 Apr 1724 - 12 Feb 1804)
German philosopher whose writings investigated rational understanding and were some of the most influential of his era. He wrote the well-known Critique of Practical Reason.
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Science Quotes by Immanuel Kant (38 quotes)
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[Aristotle formal logic thus far (1787)] has not been able to advance a single step, and hence is to all appearances closed and completed.
— Immanuel Kant
In Preface to second edition (1787) of Critique Of Pure Reason (1781) as translated by Werner Pluhar (1996), 15. An earlier translation by N. Kemp-Smith (1933) is similar, but ends with “appearance a closed and completed body of doctrine.”
[Defining Life] An internal principle of action.
— Immanuel Kant
Kritik der Urtheilskraft in Werke, IV, 260). In George Henry Lewes, Aristotle (1864), 229.
[Defining Organism] That in which every part is at once means and end.
— Immanuel Kant
Kritik der Urtheilskraft in Werke, IV, 260). In George Henry Lewes, Aristotle (1864), 229.
Enlightenment is man’s emergence from his self-incurred immaturity. Immaturity is the inability to use one's own understanding without the guidance of another. This immaturity is self-incurred if its cause is not lack of understanding, but lack of resolution and courage to use it without the guidance of another. The motto of enlightenment is therefore: Sapere aude! Have courage to use your own understanding!
— Immanuel Kant
'An Answer to the Question: What is Enlightenment?', (1784). In Hans Reiss (ed.), Kant: Political Writings, trans. H. B. Nisbet (1970), 54.
Ich have auf eine geringe Vermutung eine gefährliche Reise gewagt und erblicke schon die Vorgebirge neuer Länder. Diejenigen, welche die Herzhaftigheit haben die Untersuchung fortzusetzen, werden sie betreten.
Upon a slight conjecture [on the origin of the solar system] I have ventured on a dangerous journey and I already behold the foothills of new lands. Those who have the courage to continue the search will set foot on them.
Upon a slight conjecture [on the origin of the solar system] I have ventured on a dangerous journey and I already behold the foothills of new lands. Those who have the courage to continue the search will set foot on them.
— Immanuel Kant
From Allgemeine Naturgeschichte und Theorie des Himmels (Natural History and Theory of the Heavens (1755). As quoted in D. ter Haar and A.G.W. Cameron, 'Historical Review of Theories of the Origin of the Solar System', collected in Robert Jastrow and A. G. W. Cameron (eds.), Origin of the Solar System: Proceedings of a Conference Held at the Goddard Institute for Space Studies, New York, January 23-24, 1962, (1963), 3.
'Cosmogonical Hypotheses' (1913), collected in Harlow Shapley, Source Book in Astronomy, 1900-1950 (1960), 347.
All human knowledge begins with intuitions, proceeds from thence to concepts, and ends with ideas.
— Immanuel Kant
Critique of Pure Reason (1781, 1787), B 730. As translated by Norman Kemp Smith in Immanuel Kant's Critique of Pure Reason (1929), 569. Also translated in an epigraph as “All human knowledge thus begins with intuitions, proceeds thence to concepts, and ends with ideas,” in David Hilbert and E.J. Townsend (trans.), 'Introduction', Foundations of Geometry (1902), 1, citing Kant, Kritik der reinen Vernunft, Elementarlehre, Part 2, Sec. 2.
An organized product of nature is that in which all the parts are mutually ends and means.
— Immanuel Kant
Critik der Urtheilskraft (1799), 296. In William Whewell, History of Scientific Ideas (1858), Vol. 2, 239.
As systematic unity is what first raises ordinary knowledge to the rank of science, that is, makes a system out of a mere aggregate of knowledge, architectonic is the doctrine of the scientific in our knowledge, and therefore necessarily forms part of the doctrine of method.
— Immanuel Kant
In'The Transcendental Doctrine of Method', Critique of Pure Reason (2016), 653. Note: architectonic = the art of constructing systems.
Concepts without percepts are empty. Percepts without concepts are blind.
— Immanuel Kant
A commonly seen alternate translation of “Thoughts without content are empty, intuitions without concepts are blind.” As quoted in Critique of Pure Reason (1781), trans. Norman Kemp Smith (1929, 2016), 93.
Deaths, births, and marriages, considering how much they are separately dependent on the freedom of the human will, should seem to be subject to no law according to which any calculation could be made beforehand of their amount; and yet the yearly registers of these events in great countries prove that they go on with as much conformity to the laws of nature as the oscillations of the weather.
— Immanuel Kant
'Idea of a Universal history on a Cosmo-Political Plan' (1784). As translated by Thomas De Quinsey in The London Magazine (Oct 1824), 10, 385. Reprinted in 1859 by De Quincey in Vol. 8 of his Collective Edition of his writings.
First of all, we ought to observe, that mathematical propositions, properly so called, are always judgments a priori, and not empirical, because they carry along with them necessity, which can never be deduced from experience. If people should object to this, I am quite willing to confine my statements to pure mathematics, the very concept of which implies that it does not contain empirical, but only pure knowledge a priori.
— Immanuel Kant
In Critique of Pure Reason (1900), 720.
For the notion of matter I do not think [of] its permanence, but only its presence in space as filling it.
— Immanuel Kant
In Immanuel Kant and James Hutchison Sterling (ed.), Text-Book to Kant: The Critique of Pure Reason (1881), 128.
Give me matter, and I will construct a world out of it!
— Immanuel Kant
'Universal Natural History and Theory of the Heavens' (1755), preface. In W. Hastie (ed. and trans.), Kant's Cosmogony: As in his Essay on the Retardation of the Rotation of the Earth and his Natural History and Theory of the Heavens (1900), 29.
God put a secret art into the forces of Nature so as to enable it to fashion itself out of chaos into a perfect world system.
— Immanuel Kant
Universal Natural History and Theory of the Heavens (1755), editted and translated by William Hastie in Kant's Cosmogony (1900), 27.
I maintain that in every special natural doctrine only so much science proper is to be met with as mathematics; for… science proper, especially [science] of nature, requires a pure portion, lying at the foundation of the empirical, and based upon a priori knowledge of natural things. … To the possibility of a determinate natural thing, and therefore to cognise it à priori, is further requisite that the intuition corresponding à priori to the conception should be given; in other words, that the conception should be constructed. But the cognition of the reason through construction of conceptions is mathematical. A pure philosophy of nature in general, namely, one that only investigates what constitutes a nature in general, may thus be possible without mathematics; but a pure doctrine of nature respecting determinate natural things (corporeal doctrine and mental doctrine), is only possible by means of mathematics; and as in every natural doctrine only so much science proper is to be met with therein as there is cognition à priori, a doctrine of nature can only contain so much science proper as there is in it of applied mathematics.
— Immanuel Kant
From Preface to The Metaphysical Foundations of Natural Science (1786), as translated by Ernest Belford Boax, in Kant’s Prolegomena: And The Metaphysical Foundations of Natural Science (1883), 140.
If it were possible for us to have so deep an insight into a man's character as shown both in inner and in outer actions, that every, even the least, incentive to these actions and all external occasions which affect them were so known to us that his future conduct could be predicted with as great a certainty as the occurrence of a solar or lunar eclipse, we could nevertheless still assert that the man is free.
— Immanuel Kant
Critique of Practical Reason (1788). In L. W. Beck (ed. & trans.), Critique of Practical Reason and Other Writings in Moral Philosophy (1949), 204-5.
In every department of physical science there is only so much science, properly so-called, as there is mathematics.
— Immanuel Kant
…...
In scientific matters ... the greatest discoverer differs from the most arduous imitator and apprentice only in degree, whereas he differs in kind from someone whom nature has endowed for fine art. But saying this does not disparage those great men to whom the human race owes so much in contrast to those whom nature has endowed for fine art. For the scientists' talent lies in continuing to increase the perfection of our cognitions and on all the dependent benefits, as well as in imparting that same knowledge to others; and in these respects they are far superior to those who merit the honour of being called geniuses. For the latter's art stops at some point, because a boundary is set for it beyond which it cannot go and which has probably long since been reached and cannot be extended further.
— Immanuel Kant
The Critique of Judgement (1790), trans. J. C. Meredith (1991), 72.
It is presumed that there exists a great unity in nature, in respect of the adequacy of a single cause to account for many different kinds of consequences.
— Immanuel Kant
In Theoretical Philosophy, 1755-1770, trans. and ed. By David Walford (2003), 155.
Mathematics, from the earliest times to which the history of human reason can reach, has followed, among that wonderful people of the Greeks, the safe way of science. But it must not be supposed that it was as easy for mathematics as for logic, in which reason is concerned with itself alone, to find, or rather to make for itself that royal road. I believe, on the contrary, that there was a long period of tentative work (chiefly still among the Egyptians), and that the change is to be ascribed to a revolution, produced by the happy thought of a single man, whose experiments pointed unmistakably to the path that had to be followed, and opened and traced out for the most distant times the safe way of a science. The history of that intellectual revolution, which was far more important than the passage round the celebrated Cape of Good Hope, and the name of its fortunate author, have not been preserved to us. … A new light flashed on the first man who demonstrated the properties of the isosceles triangle (whether his name was Thales or any other name), for he found that he had not to investigate what he saw in the figure, or the mere concepts of that figure, and thus to learn its properties; but that he had to produce (by construction) what he had himself, according to concepts a priori, placed into that figure and represented in it, so that, in order to know anything with certainty a priori, he must not attribute to that figure anything beyond what necessarily follows from what he has himself placed into it, in accordance with the concept.
— Immanuel Kant
In Critique of Pure Reason, Preface to the Second Edition, (1900), 690.
Nature even in chaos cannot proceed otherwise than regularly and according to order.
— Immanuel Kant
Universal Natural History and Theory of the Heavens (1755), editted and translated by William Hastie in Kant's Cosmogony (1900), 26.
Nature, when left to universal laws, tends to produce regularity out of chaos.
— Immanuel Kant
'Seventh Reflection: Cosmogony' in 'The Only Possible Argument in Support of a Demonstration of the Existence of God', (1763), editted and translated by David Walford in Theoretical Philosophy, 1755-1770 (2003), 191
Notion without intuition is empty, intuition without notion is blind.
— Immanuel Kant
In Ralph Keyesr, The Quote Verifier, 52.
Our knowledge springs from two fundamental sources of the mind; the first is the capacity of receiving representations (receptivity for impressions), the second is the power of knowing an object through these representations (spontaneity [in the production] of concepts).
— Immanuel Kant
Critique of Pure Reason (1781), trans. Norman Kemp Smith (1929), 92.
Philosophy stands in need of a science which shall determine the possibility, principles, and extent of human knowledge à priori.
— Immanuel Kant
Critique of Pure Reason, translated by John Miller Dow Meiklejohn (1899), 4.
Reason must approach nature with the view, indeed, of receiving information from it, not, however, in the character of a pupil, who listens to all that his master chooses to tell him, but in that of a judge, who compels the witnesses to reply to those questions which he himself thinks fit to propose. To this single idea must the revolution be ascribed, by which, after groping in the dark for so many centuries, natural science was at length conducted into the path of certain progress.
— Immanuel Kant
Critique of Pure Reason, translated by J.M.D. Meiklejohn (1855), Preface to the Second Edition, xxvii.
Science is organized knowledge. Wisdom is organized life.
[Author Will Durant’s summary of Kant’s ideas; not a direct translation of Kant’s own words.]
[Author Will Durant’s summary of Kant’s ideas; not a direct translation of Kant’s own words.]
— Immanuel Kant
Although often seen, these are (almost certainly) not Kant’s own words. While explaining Kant’s ideas, this are the words used by Will Durant in 'Kant and German Idealism: Transcendental Analytic', The Story of Philosophy (1924, 1938), 295-296. The first sentence, “Science is organized knowledge,” was first stated by Herbert Spencer in 1854 (see Science Quotes by Herbert Spencer.) On the webside of quoteinvestigator.com, which pinpoints Durant as the origin of the quote, it is further explained that Kant’s writing style used complicated expression that makes it rare to find intelligible direct quotes of Kant’s own words.
The ideal of the supreme being is nothing but a regulative principle of reason which directs us to look upon all connection in the world as if it originated from an all-sufficient necessary cause.
— Immanuel Kant
Critique of Pure Reason (1781), trans. Norman Kemp Smith (1929), 517.
The instruction of children should aim gradually to combine knowing and doing [Wissen und Konnen]. Among all sciences mathematics seems to be the only one of a kind to satisfy this aim most completely.
— Immanuel Kant
In Werke, Bd. 9 (1888), 409.
The science of mathematics presents the most brilliant example of how pure reason may successfully enlarge its domain without the aid of experience.
— Immanuel Kant
In Immanuel Kant and F. Max Müller (trans.), 'Method of Transcendentalism', Critique of Pure Reason (1881), Vol. 2, 610.
Things which we see are not by themselves what we see ... It remains completely unknown to us what the objects may be by themselves and apart from the receptivity of our senses. We know nothing but our manner of perceiving them.
— Immanuel Kant
…...
Thoughts without content are empty, intuitions without concepts are blind... The understanding can intuit nothing, the senses can think nothing. Only through their union can knowledge arise.
— Immanuel Kant
Critique of Pure Reason (1781), trans. Norman Kemp Smith (1929), 93.
Two things fill the mind with ever new and increasing admiration and awe, the oftener and more steadily they are reflected on: the starry heavens above me and the moral law within me.
— Immanuel Kant
Critique of Practical Reason (1788). In L. W. Beck (ed. and trans.), Critique of Practical Reason and Other Writings in Moral Philosophy (1949), 258.
We come no nearer the infinitude of the creative power of God, if we enclose the space of its revelation within a sphere described with the radius of the Milky Way, than if we were to limit it to a ball an inch in diameter. All that is finite, whatever has limits and a definite relation to unity, is equally far removed from the infinite... Eternity is not sufficient to embrace the manifestations of the Supreme Being, if it is not combined with the infinitude of space.
— Immanuel Kant
'Universal Natural History and Theory of the Heavens' (1755), part 2, ch.7. In W. Hastie (ed. and trans.), Kant's Cosmogony: As in his Essay on the Retardation of the Rotation of the Earth and his Natural History and Theory of the Heavens (1900), 139-40.
We do not enlarge but disfigure sciences, if we allow them to trespass on one another’s territory.
— Immanuel Kant
In Preface to Second Edition, Critique of Pure Reason (2016), 18.
We ourselves introduce that order and regularity in the appearance which we entitle ‘nature’. We could never find them in appearances had we not ourselves, by the nature of our own mind, originally set them there.
— Immanuel Kant
…...
When Galileo caused balls, the weights of which he had himself previously determined, to roll down an inclined plane; when Torricelli made the air carry a weight which he had calculated beforehand to be equal to that of a definite volume of water; or in more recent times, when Stahl changed metal into lime, and lime back into metal, by withdrawing something and then restoring it, a light broke upon all students of nature. They learned that reason has insight only into that which it produces after a plan of its own, and that it must not allow itself to be kept, as it were, in nature's leading-strings, but must itself show the way with principles of judgement based upon fixed laws, constraining nature to give answer to questions of reason's own determining. Accidental observations, made in obedience to no previously thought-out plan, can never be made to yield a necessary law, which alone reason is concerned to discover.
— Immanuel Kant
Critique of Pure Reason (1781), trans. Norman Kemp Smith (1929), 20.
Without the sensuous faculty no object would be given to us, without understanding no object would be thought. Thoughts without content are void, intuitions without conceptions, blind.
— Immanuel Kant
Critique of Pure Reason, translation by John Miller Dow Meiklejohn (1899), 45.
Quotes by others about Immanuel Kant (12)
Historically the most striking result of Kant's labors was the rapid separation of the thinkers of his own nation and, though less completely, of the world, into two parties;—the philosophers and the scientists.
The Order of Nature: An Essay (1917), 69.
[Helmholtz] is not a philosopher in the exclusive sense, as Kant, Hegel, Mansel are philosophers, but one who prosecutes physics and physiology, and acquires therein not only skill in developing any desideratum, but wisdom to know what are the desiderata, e.g., he was one of the first, and is one of the most active, preachers of the doctrine that since all kinds of energy are convertible, the first aim of science at this time. should be to ascertain in what way particular forms of energy can be converted into each other, and what are the equivalent quantities of the two forms of energy.
Letter to Lewis Campbell (21 Apr 1862). In P.M. Harman (ed.), The Scientific Letters and Papers of James Clerk Maxwell (1990), Vol. 1, 711.
Pathology, probably more than any other branch of science, suffers from heroes and hero-worship. Rudolf Virchow has been its archangel and William Welch its John the Baptist, while Paracelsus and Cohnheim have been relegated to the roles of Lucifer and Beelzebub. … Actually, there are no heroes in Pathology—all of the great thoughts permitting advance have been borrowed from other fields, and the renaissance of pathology stems not from pathology itself but from the philosophers Kant and Goethe.
Quoted from an address to a second year class, in Levin L. Waters, obituary for Harry S. N. Greene, M.D., in Yale Journal of Biology and Medicine (Feb-Apr 1971), 43:4-5, 207.
Kant, discussing the various modes of perception by which the human mind apprehends nature, concluded that it is specially prone to see nature through mathematical spectacles. Just as a man wearing blue spectacles would see only a blue world, so Kant thought that, with our mental bias, we tend to see only a mathematical world.
In The Mysterious Universe (1930), 115.
Though genius isn't something that can be produced arbitrarily, it is freely willed—like wit, love, and faith, which one day will have to become arts and sciences. You should demand genius from everyone, but not expect it. A Kantian would call this the categorical imperative of genius.
Critical Fragment 16 in Friedrich Schlegel's Lucinde and the Fragments (1971), 144.
Read no newspapers, try to find a few friends who think as you do, read the wonderful writers of earlier times, Kant, Goethe, Lessing, and the classics of other lands, and enjoy the natural beauties of Munich’s surroundings. Make believe all the time that you are living, so to speak, on Mars among alien creatures and blot out any deeper interest in the actions of those creatures. Make friends with a few animals. Then you will become a cheerful man once more and nothing will be able to trouble you.
Letter (5 Apr 1933). As quoted in Jamie Sayen, Einstein in America: The Scientist’s Conscience in the Age of Hitler and Hiroshima (1985), 12. This is part of Einstein’s reply to a letter from a troubled, unemployed musician, presumably living in Munich.
The mathematical take-over of physics has its dangers, as it could tempt us into realms of thought which embody mathematical perfection but might be far removed, or even alien to, physical reality. Even at these dizzying heights we must ponder the same deep questions that troubled both Plato and Immanuel Kant. What is reality? Does it lie in our mind, expressed by mathematical formulae, or is it “out there”.
In Book Review 'Pulling the Strings,' of Lawrence Krauss's Hiding in the Mirror: The Mysterious Lure of Extra Dimensions, from Plato to String Theory and Beyond in Nature (22 Dec 2005), 438, 1081.
While we keep an open mind on this question of vitalism, or while we lean, as so many of us now do, or even cling with a great yearning, to the belief that something other than the physical forces animates the dust of which we are made, it is rather the business of the philosopher than of the biologist, or of the biologist only when he has served his humble and severe apprenticeship to philosophy, to deal with the ultimate problem. It is the plain bounden duty of the biologist to pursue his course unprejudiced by vitalistic hypotheses, along the road of observation and experiment, according to the accepted discipline of the natural and physical sciences. … It is an elementary scientific duty, it is a rule that Kant himself laid down, that we should explain, just as far as we possibly can, all that is capable of such explanation, in the light of the properties of matter and of the forms of energy with which we are already acquainted.
From Presidential Address to Zoological Section of the British Association for the Advancement of Science. As quoted in H.V. Neal, 'The Basis of Individuality in Organisms: A Defense of Vitalism', Science (21 Jul 1916), 44 N.S., No. 1125, 82.
We … find a number of quotations illustrating the use of the word [probability], most of them taken from philosophical works. I shall only refer to a few examples: “The probable is something which lies midway between truth and error” (Thomasius, 1688); “An assertion, of which the contrary is not completely self-contradictory or impossible, is called probable” (Reimarus). Kant says: “That which, if it were held as truth, would be more than half certain, is called probable.”
In Probability, Statistics, and Truth (1939), 3.
Kant … commanded the future from his study more than Napoleon from his throne.
Paraphrased from Oliver Wendell Holmes, Montesquieu: A Critical and Biographical Introduction to “The Spirit of the Laws” (1900), xiv. The context referred to “Montesquieu … a lonely scholar sitting in a library. Like Descartes or Kant, he commanded the future from his study more than Napoléon from his throne.”
The mathematical intellectualism is henceforth a positive doctrine, but one that inverts the usual doctrines of positivism: in place of originating progress in order, dynamics in statics, its goal is to make logical order the product of intellectual progress. The science of the future is not enwombed, as Comte would have had it, as Kant had wished it, in the forms of the science already existing; the structure of these forms reveals an original dynamism whose onward sweep is prolonged by the synthetic generation of more and more complicated forms. No speculation on number considered as a category a priori enables one to account for the questions set by modern mathematics … space affirms only the possibility of applying to a multiplicity of any elements whatever, relations whose type the intellect does not undertake to determine in advance, but, on the contrary, it asserts their existence and nourishes their unlimited development.
As translated in James Byrnie Shaw, Lectures on the Philosophy of Mathematics (1918), 193. From Léon Brunschvicg, Les Étapes de La Philosophie Mathématique (1912), 567-568, “L’intellectualisme mathématique est désormais une doctrine positive, mais qui intervertira les formules habituelles du positivisme: au lieu de faire sortir le progrès de l’ordre, ou le dynamique du statique, il tend à faire de l'ordre logique le produit du progrès intellectuel. La science à venir n'est pas enfermée, comme l’aurait voulu Comte, comme le voulait déjà Kant, dans les formes de la science déjà faite; la constitution de ces formes révèle un dynamisme originel dont l’élan se prolonge par la génération synthétique de notions de plus en plus compliquées. Aucune spéculation sur le nombre, considéré comme catégorie a priori, ne permet de rendre compte des questions qui se sont posées pour la mathématique moderne … … l’espace ne fait qu'affirmer la possibilité d'appliquer sur une multiplicité d’éléments quelconques des relations dont l’intelligence ne cherche pas à déterminer d’avance le type, dont elle constate, au contraire, dont elle suscite le développement illimité.”
To go straight to the deepest depth, I went for Hegel; what unclear thoughtless flow of words I was to find there! My unlucky star led me from Hegel to Schopenhauer … Even in Kant there were many things that I could grasp so little that given his general acuity of mind I almost suspected that he was pulling the reader’s leg or was even an imposter.
As quoted in D. Flamm, Stud. Hist. Phil. Sci. (1983), 14, 257.
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