"Every doctrine that is supposed to be a system, that is, a whole of cognition ordered according to principles, is called a science.".

From second paragraph of the preface to the Metaphysical Foundations of Natural Science, 4:468.

I realize he is saying that a "whole of cognition" is the same as a system, but I'm not understanding this definition. Dictionary defines system as a whole composed of relationships, essentially a mereological relationship. And then cognition? A body of knowledge?

  • what a strange question. i can't imagine someone being stuck with this particular puzzle from kant. do you mean to ask what sort of mereology kant has?
    – user71190
    Commented Jan 23 at 4:40
  • Is the dictionary definition not enough? "a product of [cognitive mental] processes*, i.e. knowledge, ideas, etc. Commented Jan 23 at 12:39
  • I think that the appendix to the Transcendental Dialectic in KrV under the title of "Regulative Employment of the Ideas of Pure Reason" is where Kant provides an answer to your question.
    – user71009
    Commented Jan 24 at 22:30
  • Cognition (German original uses "Erkenntnis") from Latin cognosco, which literally means something like "coming to know", ie. acquiring knowledge. Cognition is acquired knowledge, may it be pure or empirical. Sadly, I lack the time to look up some technical definitions of Kant atm.
    – Philip Klöcking
    Commented Jan 26 at 12:21

4 Answers 4


I think Kant's "whole of cognition" might refer to the same thing that the Ancient Greek's logos referred to -- an interactive 3-D simulation of the world that every human individual can piece together in their mind.1

Our deterministic Universe can be understood as a machine, as a giant clockwork -- understood by visualizing its virtual counterpart. For example, one could visualize an interactive model of the solar system,2 or of the banking system, or of the human mind, etc. This is logos -- and the logos is knowledge, it is the truth, and it is science.

Note that this simulation of the world is necessarily individual, each of us assembling and seeing their own copy. However, each of us can can share their simulation with others by describing what they see in their mind -- so the listener could reconstruct a copy of it in theirs, so they can see it too. That's how we can understand each other.

1 And it's not unlike the 3-D simulations that computers can do -- like realistic computer games. Our brain's visual cortex has the 3-d visualization capacity similar to that of a GPU.

2 Which we managed to do, in our minds, hundreds of years before we could actually see the solar system from the outer space.


KANT demands that knowledge which is to be called scientific must satisfy two requirements: (a) it must fit with all other knowledge of its kind into a single complete system which is constructed in accordance with an a priori idea; (b) it must be apodeictically certain.


So by cognition he means apodictic knowledge, and by whole he means a priori construct.

Right? I haven't read the link, but I would suggest diving in!

  • Kant writes: "Particular laws, since they concern empirically determined appearances, can not be completely derived from those, although they all stand under them. Experience must come in for [these laws] to become known" (B165)
    – user71009
    Commented Jan 24 at 22:27
  1. For Kant the paradigm of science was Newton’s mechanics. Newton’s mechanics employs some basic kinematic concepts like time, space, velocity and some dynamical concepts like force and energy. Moreover, Newton states general basic principles, e.g., his claim that absolute space and absolute time exist. With his kinematical and dynamical concepts Newton then formulates some general laws of mechanics, e.g., the later called laws of Newtonian mechanics.

    Newton’s mechanics is “natural science”. It sets into relation the different concepts to build “cognition”, which formulate laws of nature with the help of basic “principles”.

  2. Kant considered many of Newton’s results to be synthetically a priori, in particular to be final and necessarily valid results. According to Kant, Newton’s mechanics is an example of successful metaphysics on the field of science.

    The quote above from the "Metaphysical Foundations of Natural Science" is followed by a long terminological classification from Kant’s philosophy of science.

  3. IMO the value of Kant’s thoughts about metaphysics of science is questionable. In current physics concepts like absolute space and time are outdated , the results are no longer considered synthetically a priori.

  • 1
    Kant discusses absolute space but also explains why it is idle speculation since all experience of space is relative IIRC. That is basically the one point where he opposed Newton (like many of Newton's contemporaries).
    – Philip Klöcking
    Commented Jan 23 at 11:44
  • @PhilipKlöcking Yes, that's true. Kant combines Leibniz's and Newton's/Euler's views of space.
    – user71009
    Commented Jan 24 at 20:53
  • Kant writes: "Particular laws, since they concern empirically determined appearances, can not be completely derived from those, although they all stand under them. Experience must come in for [these laws] to become known" (B165) He doesn't think Newton's laws are synthetic a priori. The forces he discusses in MADN barely even have anything to do with Newton's forces.
    – user71009
    Commented Jan 24 at 22:27
  • 1
    Kant does not refer to kinetic energy in the Metaphysical Foundatiins, but as part of the viva controversy he refers to kinetic energy in his earliest work in 1747, Thoughts on the Estimation of Living Forces. What puzzles me in the Metaphysical Foundations is where is the metaphysics in what appears to be a work of Newtonian science? Or something similar? We wouldn't ordinarily refer to the Principia as metaphysics.
    – Gerry
    Commented Jan 25 at 23:57
  • 1
    @Gerry Yeah, Kant later himself discovered that his account is circular and merely mathematical. That's the problem (or one of the problems) that he was attempting to solve in his Opus Postumum. Hegel also noticed it, in 1801. Cf. Kenneth Westphal, On Hegel's Early Critique of Kant's Metaphysical Foundations of Natural Science.
    – user71009
    Commented Jan 26 at 4:19

I'm gonna take a stab at answering my own question based on the feedback you all have given me. Not sure if it's right, but then I know you all will correct me.

By cognition, I think he means a process of knowing or learning of which there are many types, e.g., metaphysical, logical, mathematical, empirical, practical, etc. A "whole of cognition" would be one of these types, e.g., empirical knowledge would be one whole process that one could consider independently of the other types (even though they are all related through reason).

So then if I take one of these processes, like empirical reasoning, and if I order them systematically according to foundational principles, then I have created a science or a Gewissenschaft, in this particular case, a natural science.

That's what I think he means.

  • A cognition or Erkenntnis is the outcome of this process, ie. sentences (of knowledge) with a truth value. The systematic aspect is a fitting together according to principles and while these principles may themselves be cognitions, Kant does not exactly put the process or action of doing science to the fore, even if he insists that the sources of knowledge for each cognition are to be kept apart to characterise it as pure or empirical. This is the main twist that happened only with Hegel some years later, who emphasised the scientific process over particular cognitions.
    – Philip Klöcking
    Commented Jan 26 at 12:28

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