‘Philosophy’ has always been Bunk: Kant’s Noumena and Phenomena

(I’ve kept all parts of Kant on Knowledge together, so this chapter is awfully long.  The nub of it is down to the first horizontal line.  Takethe rest in easy stages.  I’ve left Kant’s Ethics to another chapter.)

Kant felt he had achieved a revolution of Copernican proportions in Philosophy by coming up with hisTranscendental Idealism — which very roughly is that we can never know things in themselves as they really are!  These things-in-themselves are the noumena.

All we can ever sense or know are the phenomena which result from pre-existing faculties in our minds shaping the sensations coming in to us from the noumena of the outside world (and also from the contents of our inner world).  Such mental faculties of ours are concepts like Causality, Space, Time and many others, which are in our minds! and not out there!

Bertrand Russell said over a century later that, for knowledge to count as knowledge, it (obviously) has to be of things and their properties as they really are.1   So what Kant was saying didn’t solve anything and was a soporific for him.

Kant said that knowledge doesn’t only come from the sensations, as the British Empiricists had been saying for well over a century.  No, he said, the mind doesn’t arrive at birth a blank slate, a tabula rasa, upon which the senses later simply imprint Knowledge.  No, the newborn child comes equipped with prior faculties lying latent in the mind.  These faculties eventually contribute to knowledge of the outside world and of its own interior world.

Kant stated that we receive sensations of the outer world and of our inner world, but they are then mediated through our minds.  They become the phenomena of our Empirical Knowledge.   We do not know things-in-themselves unmediated by these mental functions.  These later are the noumena.

Kant’s revolutionary new point (against the Empiricists) was that, rather than our minds having to conform purely to the senses, it is our minds that help constitute our world as we sense it.

To understand what started Kant off, we have to go back to Hume.  Hume had been a British empiricist who believed that all knowledge came from sensation.  But, in 1739, he published his shattering vision that some of our most cherished axioms of belief don’t in fact come from sensation!   Our belief in Cause and Effect, for instance, doesn’t — the inevitability of effect following cause isn’t a sensation that comes to us from the world.2 All we get from the world are sensations of specific happenings or events, and these don’t include Causality. Causality isn’t a happening or event.  Hume must have meant that it was a theory or supposition.  And belief in Causality isn’t valid logic either — just because the sun has always risen doesn’t mean logically that it will rise tomorrow!  It is the fault of so-called Inductive Logic to assume that just because something has always happened, that it’s always going to.  The inference isn’t logical.

If we perceive that some events cause other events, that is because our mind has the faculty of making sense of events in terms of cause and effect.  This spurred Kant into working out that Causality (and other concepts) was something in our minds that we add to sensations to produce what we think of as knowledge.

(Derived from here3, I think:) Space and Time are two such other faculties of Mind among many others.  They don’t come to us from the outside world as sensations.  As far as Time goes, for example, our minds arrange sensations in a temporal progression.  Similar remarks apply to Space but I presently can’t trace them.

Kant said that these faculties, functions or concepts, in our minds are a priori in that they are prior to sensation, and ‘synthetic’ in that they do provide knowledge and not just repetitive tautologies of the definitions or meanings of the words used, such as ‘all bachelors are unmarried’.

Science is based on these mental functions that mediate the sensations, including that of cause-and-effect, time, space and others, and therefore based on phenomena.

Kant invented the term Transcendental Idealism for these faculties inside the mind.

Hume’s revelations, that causality isn’t among the sensations, and that ‘Inductive Logic’ is false logic, threatened to undermine the logic of science and its claim to Truth.  (It was perhaps only in the 20th century that Popper said that Science is not based on induction, but on hypothetico-deduction.)

Hume however added a cryptic comment, that, though Causality wasn’t something empirical or rational, yet it is based on human experience and ‘the basic laws of thought’.  Some interpreters have tried to squeeze that last remark into meaning the same as Kant ‘s ‘prior faculties of the human mind’.1

Kant’s theory gave rise to the later pottiness of German Idealism — of Fichte, of the two Schlegels, and of Schelling.  These philosophers threw out noumena and argued that everything was in the mind and consisted of mental phenomena.  There was no Reality, no Noumenon, out there.3    Bertrand Russell, as I remember, called the philosophy of one of them ‘insane’.

Kant was against the pure Rationalists who with their Metaphysics had tried to reach knowledge about profound matters like God, the Universe, and Life after Death, without sensory input to begin the process.  He believed in the necessity of the sensations   To an extent, he brought Empiricism and Rationalism together.

That’s the nub of Kant on Knowledge.


Kant’s ‘Transcendental Idealism’

‘Idealism’ refers to the broad group of theories that say that things apparently out there in the world, are actually in our minds!  ‘Realism’ refers to the theories that say that things apparently out there really are out there.

Transcendental Idealism is the title that Kant gave to the a priori, synthetic judgments that the mind contributes to empirical knowledge, that he had discovered.  He also called them the ‘transcendental conditions’.

In Berkeley’s Idealism, which seems to have been the original Idealism of that age, something is an object only if or when it is perceived.  In Kant’s transcendental idealism, the object exists in reality even when not perceived.  It is just that our faculties of mind or ‘conditions of sensibility’, such as space and time, provide the ‘epistemic conditions’ (Henry Allison’s term) for us to know objects as phenomena.4

It seems Berkeley had already used the concepts of Phenomenon and Noumenon: that all we can know are the mental impressions, i.e. the phenomena, that the outside world creates in our minds; and that we know nothing of the things-in-themselves, the noumena.  Berkely also said that things only have permanent reality in that God is always perceiving them.5

Kant said that our mental faculties order things and events and ‘make it intelligible’.  We could not understand reality if we did not have minds equipped with a rational structure. The world appears rational, not because the world is rational but because the mind is.

And still from here 4, though I don’t quite grasp it so can’t put it into my own words but include it for its philosophical flavour:  Kant refuted idealism.  To answer criticism that his transcendental idealism denied the reality of external objects, Kant seems to have argued that our self-consciousness presupposes the reality of external objects in space.  Defining self-consciousness as a determination of the self in time, Kant argues that all determinations of time presuppose something permanent in perception and that this permanent cannot be in the self, since it is only through the permanent that one’s existence in time can itself be determined.  (This argument inverted the supposed priority of inner over outer experience that had dominated philosophies of mind and knowledge since Descartes.)


It seems very important to Kant that his functions of Mind were recognized as ‘synthetic’ and ‘a priori’. 

Empiricist Hume and rationalist Leibniz had previously recognized only two kinds of statements.  These were the analytic, a priori ones, and the synthetic, a posteriori ones.  They thought that no statements fell outside these two kinds of statement.  They had to be the only ones.

(Derived from here6, among many other sources:) A priori means that the statement is true or false independent of experience, of sensations from the outer world or from the inner world of our own minds.  A true a priori statement is necessarily true by virtue of its own words.  That old chestnut of a statement, ‘All bachelors are unmarried’, is a priori.

Analytic statements are true or false by virtue of the meanings of the terms used — the meaning of the predicate is already contained within the meaning of the subject, as in ‘all bachelors are unmarried.’  They are always and everywhere true, i.e. universally true; and necessarily true too in that they cannot be otherwise.

(I seem to have written the same definition for ‘a priori’ as I have for ‘analytic’ but that’s perhaps how they are.  I am too philosophically exhausted to read through them again.)

An a posteriori statement depends on sensation coming from the outer world or the inner mental world, such as ‘some dogs are black’ or ‘all swans are white’ or the feeling of geriatric tiredness.  It is synthetic too, i.e. adding to information, in that it doesn’t just depend on the meaning of words in predicate and subject.


So for Hume and others, there were only two kinds of statement possible: synthetic, a posteriori ones, and analytic, a priori ones.6

So Kant’s theory that there can be statements, judgments, truths, that are synthetic (providing information, not just re-hashing meanings of words), as well as being prior to sensations, was new.6 He argued that mathematics and scientific principles were such, as were all those other faculties of mind that contribute to creating the phenomena.

‘7 + 5 = 12′ is a priori because it is a necessary and universal truth independent of experience, and synthetic because the concept of ’12’ is not contained within the concept of ‘7 + 5’.


Kant against Metaphysics

Kant felt he had achieved a revolution of Copernican proportions in trying to divert the continental Philosophy of his day (as by Descartes, Spinoza and Leibniz) from discovering truths about reality by pure thinking in the mind, i.e. by metaphysics.

He was against these pure Rationalists who with their Metaphysics tried to reach knowledge about matters like God, the Universe, Life after Death, Time and Causation, by pure Reason without sensory input to begin the process.

He believed that the mind did contribute something, but it was by way of its inborn faculties to shape our sensations.  This, it is said, was a shift from metaphysics to epistemology, which remains to this day in Philosophy.6

Incidentally, Kant’s book title ‘Critique of Pure Reason’ simply meant that he was criticizing the notion that Reason could reach knowledge on its own.  It was directed at Leibniz’s rationalism and against metaphysics in general.7,8 It wasn’t intended to contrast Pure Reason with the Practical Reason of Ethics, which latter he dealt with in another book.  (It is stated that it was also because Kant was against Hume’s empiricist scepticism about the possibility of any scientific knowledge at all, but I don’t see how this helps justify the title.)

Hume, already before Kant, had rejected metaphysics because it consisted only of rationalistic speculation in the head without grounding in sensation.3 I would have thought that Empiricism as such, even before Hume, was in its very nature a radical rejection of metaphysics.

To see Kant’s new departure in another way:  He argued that the pure Rationalists assumed that ultimate profundities were in an external reality that the mind must reach out for, rather than inside the mind in the form of its inborn faculties.3 Or in other words, which I don’t quite understand, Kant differed from the Pure Rationalists by claiming that Pure Reason can discern the form but not the content of reality.

Kant rejected metaphysics also because he saw it as the attempt to know the world-in-itself by synthetic a priori reasoning, instead of understanding that this kind of reasoning only contributes to our knowledge of the phenomena.  (Mmm! That sounds like proving something by assuming it’s right.)

However, at least one interpreter sees Kant’s system of prior mental faculties contributing to experience, as being a kind of metaphysics.

Here is something I don’t understand: That Kant thought there may be things in the universe that we don’t have either the sensory or mental faculties to apprehend.  Although these things are real in themselves, they are not real for us. We have certain ‘predispositions’ (which I suppose means our prior mental orderings) as to what exists, and only those things that fit into these predispositions can be said to exist for us.


Here is a whole list of some of the prior faculties of mind that Kant discovered, what they are and do, and what they should be called.  Here is my understanding of them, as best I could.  These next two sections are difficult and are liable to give one terminal ennui.

There are features of the world that we know without experience or experiment.  We know that if a stone rolls downhill, there must be some cause, even though we don’t have a clue what it is.9

If we put 3 apples in a bag and then 5 oranges, we are certain we will end up with 8 pieces. We don’t have to perform an experiment or count them.

Also, we are certain that the space around us is going to be describable in terms of geometry.  For instance, if the floor is perfectly level and the wall is perfectly perpendicular to it, the resulting angle will be exactly 90 degrees.

Kant wondered how we can know such necessarily true features, prior to any experience.  They are not analytically true by virtue of simply re-hashing the meanings of the words used, such as that old chestnut ‘all bachelors are unmarried’.  That latter is just true by virtue of simple logic.

So, the question is how are synthetic, a priori judgments possible?  How do we know there is a cause that makes that stone fall down?  How do we know there will be 8 pieces of fruit in that bag?

Madison Morrison in his An Elementary Introduction to Kant’s Terminology  gives us more words that Kant used and what they meant.10 I find Kant’s terminology, and those of his interpreters, confusing.

Morrison uses the term Epistemic Dualism (that others had already used) for Kant’s overall theory that Knowledge comes from the duality of Sensations and Reason.  No confusion there.

Morrison gives Kant’s meanings for words that he (Kant) uses, such as sensation, experience, sensibility, categories, intellect, concepts, percepts, intuitions , imagination, content, understanding, reason, subjectivity, objectivity.  That is necessary because many of these words have different meanings in ordinary usage; and some interpreters of Kant give different meaning from those he himself gave.

According to a site no longer available, Kant called Space and Time the ‘forms of perception’, and that these are the first things in the mind to be married up with sensations.  The second things to be married up are ‘the forms of conception’ (which are the ‘categories of thought’), but I don’t understand what either of those terms mean!

Space and Time are also called ‘sensibilities’, or ‘pure intuitions of our faculty of sensibility’, or ‘forms’ of perception!11 From elsewhere, I got the terms ‘forms of sensibility’ and ‘categories of understanding’.  What did Kant or others mean by them?

Kant called one of his mental functions ‘Category’.  He divided Category into four groups of three: quantity (unity, plurality, totality); quality (reality, negation, limitation); relation (substance, cause, community) and modality (possibility, existence, necessity).7,12

I wonder if these owe something to Aristotle’s Logic.  Within Category is Number.  I am awash in a sea of vague understanding.

We are told that Kant had found these prior faculties of the Mind by deductively working backwards until he could go no further. The Categories represented ‘the very bottom level of conceptual organization’.

Kant thought that our number sense also isn’t from sensation but comes from our intuition of successive moments in time.  Geometry comes from our intuition of space.3

And the concept of causality is in our ‘faculty of understanding’.

Kant thought that we need the senses to become aware of an object, but we need Understanding and Reason (which presumably simply means the prior functions of Mind) to form any conception of it.12

In another site I now can’t trace are more explanations of what Kant and his interpreters meant by terms like ‘sensibility’, ‘physical and mental sensations’, ‘outer sense’, ‘inner sense’, ‘intuitions’, ‘faculty of understanding’, ‘inertia’ in physics, ‘concepts’ per se, the ‘logical perspective’, the ’empirical perspective’, and ‘judgments’.  But they lacked clear examples to enable me to understand.

The next two paragraphs are even more difficult but I felt I couldn’t leave them out:

On top of these difficulties in understanding Kant, there have also been difficulties translating him into English:  A site I now can’t trace tells us that Kant’s sinnlichkeit is translated into English as ‘sensibility’ and means roughly the ability to have ‘intuitions’.  (But what does ‘intuitions’ mean in philosophy?)  Each of ‘sinnlichkeit‘ and ‘sensibility’ is contrasted with the ‘understanding’ which is the ability to have and use concepts.  (I wrote at some stage, wrongly I think, that the ‘understanding’ simply means the prior faculties of Mind).  The German word Empfindung is translated into the English ‘Sensation’, and each of them means the stimulation of one’s senses by the real presence of a thing-in-itself affecting them.

The previous paragraph shows that ‘sensibility’ and ‘sensation’ are etymologically related in English, but their translations into German, Sinnlichkeit and Empfindung aren’t. (I now lose full comprehension of this paragraph that I have largely got from elsewhere.) And they are in fact two unrelated concepts:  ‘Sensibility’ in English means the ability to imagine, i.e. to form intuitions of things not actually there, and also to have intuitions of pure mathematical objects such as pure circles which don’t exist as actual objects.  It is precisely because of the difference from sensation, from Empfindung, that Kant thought there was an ‘a priori, formal dimension of intuition’.   So, says this site, ‘we should define intuition without reference to sensation as an immediate singular representation in space and time’.

As if the above section is not enough to sink one, there was also available on the Web, Morrison’s Intermediate and Advanced Introductions to Kantian Terminology.

Macaulay, the historian, was exasperated that he could not understand a word of The Critique of Pure Reason.14 It is said to be very long and almost unreadable due to dry prose and complex terminology.3,9 Kant published Prolegomena to Any Future Metaphysics two years later.  While hardly a page-turner, it was much briefer and more accessible.

Isolated Comments:

There may be some disagreement among Kant and his interpreters on whether all of the prior faculties of Mind are already fully developed at birth.

To attempt some plodding Thought of my own which must have been done already: I would say that Causality is within our sensations when we see that the same sequence of events happens over and over again.  It is seen to be constant and inevitable; and later it is discovered by science what exactly it is that makes it inevitable.

I think Russell, in his opinion of Kant’s idealism as a soporific, added that putting concepts essential to Science like Causality into the mind rather than into the world was just a convenient side-step that solved nothing

Bertrand Russell seems to have said also that the noumenon of anything consists of particles whizzing around inside the atom, as the physicists later discovered, and these are entirely different from the phenomena that our senses mediated by our minds give us.



  1. http://blogs.britannica.com/2011/05/influence-david-hume-editor/
  2. https://en.wikipedia.org/wiki/Logical_positivism#Analytic/synthetic_gap
  3. https://www.sparknotes.com/philosophy/kant/section1/
  4. https://academickids.com/encyclopedia/index.php/Immanuel_Kant
  5. https://www.philosophybasics.com/movements_german_idealism.html
  6. https://www.sparknotes.com/philosophy/kant/themes/
  7. http://peace.saumag.edu/faculty/kardas/courses/HP/Lectures/kant.html
  8. https://en.wikipedia.org/wiki/Critique_of_Pure_Reason
  9. https://www.shmoop.com/study-guides/literary-critics/immanuel-kant
  10. http://www.madisonmorrison.com/topics/kant-and-chinese-literati-landscape-painting/an-elementary-introduction-to-kants-terminology.html
  11. http://www.historyguide.org/intellect/lecture23a.html
  12. https://www.philosophybasics.com/philosophers_kant.html
  13. http://www.philosophybasics/
  14. Manfred Kuehn, 2014, Kant: A Biography, Cambridge University Press










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