Boer is Professor of Philosophy at the University of Leuven,
Belgium. She is the author of Thinking in the Light of Time:
Heidegger's Encounter with Hegel (2000) and On Hegel: The
Sway of the Negative (2010), as well as of numerous articles
on Kant, Hegel, classical German philosophy, and Heidegger. She
also co-edited, with Tinca Prunea-Bretonnet, The Experiential
Turn in Eighteenth-Century German Philosophy (2020).
Welcome to Philosophy Podcast where we interview leading
philosophers about their recent books. Today I'm speaking to
Professor Karin de Boer about her book Kant's Reform of
Metaphysics: The Critique of Pure Reason Reconsidered. And a couple
of endorsements, this is from Paul Franks, Yale University. De Boer
has succeeded in writing a much-needed account of Kant's critical
philosophy as the salvation not the destruction of metaphysics,
correcting the epistemological focus of over a century of Kant's
scholarship. Her illuminating rereading in light of the metaphysics
of Wolff and Baumgarten, and her scrupulous reconstruction of the
system of pure reason that Kant intended but never completed, make
this book essential reading for anybody interested in Kant's
And Carl Aric of University of Notre Dame. De Boer shows in
detail how Kant's critical aim was to reform metaphysics as a
system, not to reject it altogether, and especially valuable
feature of her discussion is its focus on Conant concern with
Wolf's philosophy and the metaphysical question of how metaphysics
as a science and pure reason is possible at all. Yeah. Karen Dubbo
is the author of Thinking in the Light of Time, Heidegger's
Encounter with Hagle also on Hagle the Sway of the Negative. She
also co-edited with Tinka Prenaya [inaudible 00:01:49] , the
Experiential Turn in 18th century German philosophy. Professor
Karen De is professor philosophy at the University of Lu van in
Belgium. Welcome to Philosophy podcast. So tell me, when I read
those endorsements, they talked about you're having a different
interpretation and something about epistemology having been
dominant before and you're emphasizing something else. Could you
give us an overview of that?
Yes, sure. So maybe I can clarify the take on the reason that
I developed, starting from a very simple example, namely the
principle of causality. So the concept and the principle of
causality are very often used to clarify Kant's project, but I
think that has an interest in this concept and in other concepts
that is maybe somewhat different from what we take it to be. So
normally we would consider Kant be interested in the concept of
causality because causality is seen as a principle that makes
possible our empirical judgments about, for instance, colliding
billiard balls. So that would be an interest in the concept of
causality. That has to do with the way we acquire knowledge of
things. So that could be called the epistemological approach. So as
I just said, I think that Kant was interested in the concept of
causality also for a different reason because he noticed that his
predecessors and contemporaries also used the concept of causality
to make statements about gods.
Yes. For instance, by positing, by arguing that God is the
cause of the universe. And for Kant, this was a very problematic
statement. Yes. Because in fact, what the meta physicians were
doing on his account was just combining two concepts, but there was
no bearing to actual empirical cognitions. And as you probably
know, yum had a similar criticism. Yes. Yum also thought that it
was very problematic to speculate about God and to claim that God
is the cause of the universe. And as is well known, Kant took Yum's
skepticism in this regard extremely seriously, but Kant thought
that we could not just get rid of metaphysics in the way Yum
proposed. Because according to Kant, it was really important to
conceive of causality as a pure concept. That is to say as a
concept that is part and parcel of the hardware as it were of the
human mind that is not just a concept such as all kind of empirical
concepts that we develop through experience.
So Kant wanted to preserve the concept of causality as an
absolutely necessary concept because he thought that only in this
way can we account, as it were for the objectivity of our empirical
knowledge. So I think that if we only think about Kant's project as
a project that is interested in causality in relation to empirical
knowledge, we miss, as it were, the other part of the story, namely
Kant's concern with the use of the concept of causality in a
speculative metaphysics. In my book, I tried to shift the focus
from the parts on let's say the conditions for empirical cognition
to the part where Kant develops his criticism of former
metaphysics. But unlike many other authors, I take this criticism
of former metaphysics to as it'll motivate the project as a whole.
And so I take count also in the early parts of the work, including
the transcendental deduction, to be concerned with the limits
within which the concept of causality can be used. I hope that this
And as opposed to Hume, he's not trying to get rid of
metaphysics, he's trying to reform it. But it is a limitation,
isn't it? Or perhaps you don't think of it that way.
Yes. I take reform of metaphysics to indeed consist in a
limitation of metaphysics, yes? So what he opposes, what he
rejects, as I already mentioned, the tendency of metaphysics to
speculate about God, the soul, or the world as a whole, completely
divorced from the realm of possible experience. That is something
that Kant rejects, at least with regard to our theoretical
cognition. But he thinks that metaphysic still has a really
important task, namely to identify all a prioritized concepts as he
calls them. That is to say all concepts that have their origin in
the human mind per se. So he takes this to be an important task for
metaphysics that needs to be preserved also within the modern
Right. And so you speak of him having an inner end in the
text, which is this system of pure reason. That would be what
metaphysics will look like in his mind. And you describe it, or
maybe it's a translation of German, it's an inventory, it's a list
of, it's limited. It's not about God or the world or the soul as
such. And instead it's a inventory, I think of it. Tell me how you
think of it as a list of synthetic statements.
Yes. That that's partly correct. So in fact, already develops
a small version of this system within the critique of pure region
itself, yes? Most importantly, he puts forward the famous table of
categories, which is just a list or invent of 12 basic concepts
that according to Kant as it were necessary, piece of positions of
any cognition that we can achieve of any knowledge that we can
achieve. So we find in the critique itself already a minimal
system. And I think that ambition was to increase this system, and
that is to say to also deal with more specific concepts that are
not presuppositions of any knowledge whatsoever, but for instance,
are necessary presuppositions or principles for the actual natural
sciences. Instance, a concept such as force or movement should also
be included in the lists.
These concepts are not yet presented systematically within the
context of the critique of pure reason itself. But accordance to
Kant all particular sciences share, as it were, the basic
conceptual framework already presented in a critique of your
reason. But they also are based on a set of specific principles
that is to say principles that are specific to, for instance,
physics or psychology or any other discipline.
I think you described that there was this distinction I
thought was helpful between maybe he started out in the role of
judge, but along the way took on the role of architect or designer
one might say. Could you explain that? I thought that was
Yes. I think this is indeed an important distinction because
it pertains to the two separate tasks that Kant tries to carry out
in a single book. Maybe this is not something that we should advise
our students yet to identify two tasks and carry them out
simultaneously. Because it stuff gets very complicated. So maybe it
would be preferable to do the first thing first and then move on to
the other task. But I think that for Kant, this was impossible. So
what are these two tasks? Maybe I start with the task of the
architect, and this I think is something we have already discussed,
yes? Namely providing a systematic account of all the pure elements
of our actual cognition. That is to say the concepts and principles
that are necessarily presupposed in our actual knowledge of
objects. So the accounts in his capacity as an architect is
concerned with presenting the various lists of concepts in a
systematic manner. And Kant thought that his predecessors in
Germany had already done this to some extent, but hadn't done a
And they... Go ahead. Right.
So maybe I can first move to the other task, the task of the
judge. And this is something that Kant emphasizes in the prefaces,
namely the need to, as it were, step back from the work of the
architect and to investigate how metaphysics can be established as
a science in the first place. And in order to answer this question,
the classical task of providing a systematic account of all these
aporia elements must be interrupted in order to ask a more
That is the question, what are the ultimate conditions of
metaphysics itself as a discipline? So in this case, we are not
interested in the conditions of physics or empirical cognition more
generally, but in this case, we are interested in the conditions
that make it possible to do metaphysics in the first place in an
adequate manner. And I take it that Kant uses the metaphor of the
judge to explain this part of the word. The second task, as it
were. So the judge doesn't do anything but assesses the various
claims that have been made by meta physicians, but also by the
skeptics. And the judge assesses, as it were, the validity or lack
of validity of the various claims that has had been made.
Right. And I thought one of the really interesting
distinctions was what Kant is doing is restricting not individuals,
but the discipline of metaphysics, in other words. Well, maybe you
could elaborate on that. It's not a restriction on what people will
do. It's a restriction on what the field of medic physics should
Yes, exactly. Well, I think that the term individual is maybe
not sufficiently specific because individuals can be engaged in all
endeavors. I think I can answer your question by looking in
particular at what individual scientists do, yes? For instance,
when they are engaged in physics. Now on my reading, the scientists
who actually engage in empirical research, they are not limited
whatsoever, yes? They can go on with the investigations
indefinitely. Kant doesn't really put a limit on the activities
carried out by the scientists. And maybe this is not sufficiently
appreciated by scholars. That in that regard there's no reason for
the scientist to be modest. Kant's philosophy is often associated
with a requirement to be modest, yes? I don't think this is correct
because I think that Kant is, as you just mentioned, is interested
in the existing tendency of metaphysics to go beyond any bounds.
And he wants to restrict metaphysics. Such that it takes upon
itself a mother staff, namely systematically organizing these
various aporia elements of our knowledge.
Right. I think that the quote I had was the restriction is
imposed not on the human mind as such, but on the field of
metaphysics, because isn't there the sense that humans not, instead
of looking at professional philosophers, look at everyone, we're
going to naturally do metaphysics in our head. And it's not my
understanding of what you're saying is he's not saying there's
anything wrong with that. He's saying in the field of metaphysics,
it should be restricted. Is that the way you see it?
Yeah. Yes. That's the way I see it. And I think that Kant
would also affirm that it's perfectly fine for human beings and
perfectly purposeful in at least a number of cases. For instance,
to believe in God. What you believe in immortality of the soul. So
Kant is not against human beings who believe in God or in the
immortality of the soul because his concern is the action
supportive or not. If it's supports individuals in having a certain
hope, or if it supports them in acting morally, then believing in
god's or in immortality of the soul is perfectly fine. So again,
this I think illustrates that Kant was not interested in delimiting
human cognition and human activity in general. No, he investigates
human cognition and human action for the purpose or for the sake of
clarifying what the limits are of the traditional type of
Maybe what is getting confused for people is this idea that
there is Kant saying that there is this nominal realm, but we can
have no access to it. That's not to say that we can't have
synthetic truths, but there is this realm out there that we're not
going to be able to tap. That is the source maybe of this idea that
he is all crushing.
Yes. That is indeed an important point and has also been an
important bone of contention in the literature. Now, my way of
looking at this is as follows. I think that we should first of all
get rid of the expression there is that you used. Yes. You say
There is a nominal realm.
There is a nominal realm, and I don't think that Kant would
normally use this expression. And more generally, I think it is
being used way too often in philosophy. One thing I learned from
Kant is that there is expression or question is relevant to
Or at least to the type of philosophy that Kant's is doing.
Yes. So Kant doesn't posit that there is this realm outside of us,
to which we don't have any access. But he tries to clarify, as it
were, from within his investigation of the human mind, how we can
on the one hand engage in unifying our appearances. That is to say
how we can produce empirical knowledge, on the one hand, but how on
the other hand, the human mind is also able to produce ideas such
as the idea of God or the idea of the soul. So he's not positing
anything, he's just, as it were, clarifying how the human mind
operates, how it can operate on stuff out there or stuff that we
get access to through our senses. But how your mind can also
operate in a different manner and produce the idea of God, the idea
of the soul, the idea of freedom, et cetera. And so Kant then
further reflects on this distinction just on the two directions
that we can take in so far as we try to think about things.
No, I understand. That's very helpful. I think one of the
things you observe is that the project, his lifelong pursuit was to
turn metaphysics into a science or to reform metaphysics by turning
it into a science. And so all those words need some help there. But
what was metaphysics like at his time, supposed to now, and I
wondered if you could give some concrete examples of what was wrong
with metaphysics at the time. Any theories out there that he
thought were really harmful or?
Yeah, there were several problems that he identified. I have
already discussed one earlier on in this conversation, namely the
tendency of meta physicians to make judgments such as God is the
cause of the universe.
Okay. Yeah. Gotcha.
And in this, the judgment looks very similar to an empirical
judgment such as the swan is white. Or this movement is the cause
of the second movement, right? The structure of these judgments is
very similar, but Kant thinks that the judgment about God is
basically elusory. It's just a combination of two concepts, but in
the way the concepts are being combined, no real object is being
generated. So there is an emptiness to this judgments, which is not
acknowledged by the meta physicians. Because they took their
judgment about God, for instance, to be the pinnacle of
So this is something that we already discussed, but there is
an other problem that really bothered Kant and that he tried to
solve and that is somewhat related to this one. And so the other
one concerns the discipline of cosmology and cosmology was
considered to be a part of metaphysics that was very different from
actual physics. And that consisted in a number of speculations
about the world as such. But of course, we cannot observe the world
as such, or the world as a whole. We only can observe bits and
pieces of the world, but many of Kant's predecessors and even
contemporaries, they debated about questions concerning, for
instance, Monas. Yes, of course this is an idea that they took over
from lightness, but they had very heavy and animated debates about
whether a Mona takes up space.
So how can we know whether a Mona takes up space just cause
Mona by definition cannot be perceived by the census. So these
debates and controversies about Mona, for instance, were really
focal, very problematic. And I guess that he was also personally
irritated by these books and articles where these controversies
were discussed. And he probably also got irritated by his own
earlier attempts to contribute to these debates. So the critique of
pure reason is in a way also a critique of Kant's own earlier
position. And so he developed his ideas and emancipated himself, at
least to some extent from his earlier assumptions, which were more
or less the [inaudible 00:23:23] ones.
Right. And so is it fair to say that on the epistemological
front, which maybe has been the focus, Kant was responding to Hume
who was saying we couldn't really know much, but on the
metaphysical, I think you also point out that the terms
metaphysical and epistemological would not have been Kant's terms.
But anyway, on the side that you're emphasizing, he was saying
humor was wrong because he was too limiting, and the meta
physicians were need to be reigned in because they are too
expansive or have too much flying too high.
Yes, exactly. Yeah.
I think one of the things I think it's very appealing about
this idea is that there is this... Okay, so in one sense he was in
the critique of pure reason. He was going about doing this second
order critique, but along the way you have much of this general
metaphysics. But in the other sense, it was never something that he
actually finished or never really wrote a second, wrote this all
up, I guess you could say. And it gives you this sense of this lost
manuscript or this unwritten manuscript, which is really intriguing
because you want to know what it would say, but why was it not ever
finished by him or anyone else?
Yeah. Okay. That's a good question. Yeah. So in the final
chapter of my book, I tried to provide an outline of consistent by
dealing with the various main parts and also filling in some of the
details to the extent that I could do so relying on his lectures on
sections of the critique of your reason itself.
Letters of the people.
So for me, this has been important because in this way I think
I could provide a different vantage point from which we can, as it
were, reassess the whole project. Yes. The critical part and the
aim that Kant had set himself. So that I think is the relevance of
this final chapter. Not so much because we now know exactly what
Kant had in mind with his future system or his future metaphysics,
but because it allows us to put into perspective as it were, what
he actually did in the critical pure reason. So that that's maybe
one part of the answer. The other part of the question is, well why
didn't Kant go on and actually sit down to write this system of
pure reason or metaphysical system that he promised at various
points in the text? And there I think we can only speculate yes,
and just said Kant was not really in favor of speculations, but as
readers and writers, we can not avoid engaging in a little bit of
speculation from time to time.
So as you know, Kant felt that he had to carry out a number of
other tasks after the critique of pure reason. No, he went on to
write two more critiques and he went on to write a number of other
works as well. And as I also suggest in the book, I think that Kant
in a way lost interest in this metaphysical system. And as he took
almost 10 years to write the critical, so it is very possible that
the aim he set himself, let's say the late 1770s, had maybe lost
some of its appeal once he had finished at the time he had finished
the book. And it's also possible that he realized gradually that
carrying out the task of the architects in a full-fledged manner
would be more complicated. Then he had suggested in the critique of
pure reason, so it could be a combination of both that he felt that
other tasks were more pertinent. And maybe he was also somewhat
discouraged because he realized that the task of the architect was
more complicated than he had thought.
Well, I'll speculate also, but this is just from reading your
book, that it seemed like he thought maybe this was something for a
student or someone an heir to do that that was not really his
forte. That was my only read on it.
Yes. So these passages where he basically suggests that his
students and followers could easily carry out the work they suggest
that Kant was very optimistic about the possibility of writing up a
Just write it up.
Just write it up. But as I just said, it's possible that after
the publication of the critique reason, Kant gradually realized the
obstacles that might be in the way of a satisfactory elaboration of
the metaphysical system. Now, what I did not really discuss at
length in the book is the fact that some of Kant's students took
his message to heart and did try to elaborate a meta fiscal system.
And after I published my book on country reform, I wrote an article
on Schmid who was not exactly Kant's student but someone who very
early on started teaching a concept of reason in [inaudible
And the book chapter is not yet published. But I thought it
was really fascinating to see how someone at the time, based on
Kant's own indications and some thinking to do the job, and maybe
it's not very satisfactory, but at least I think it's of interest
for story philosophy to see that there was something going on with
regard to this idea of a philosophical system in between [inaudible
00:29:34] on the one hand, and for instance, Reinhold and Fester
and Hagle on the other hand. Because the German idealists also had
this ambition to develop an encompassing philosophical system, not
call it metaphysics, but in fact there is a lot of continuity
between the idea of a metaphysical system if you look at what Kant
has to say about it. And if you look at what Fester and Hagle, et
cetera have to say about it. But as said, I was really fascinated
by this attempt, by this unknown figure called Schmidt to develop a
metaphysical system on the basis of Kant's own indications.
Especially since you had just thought about how you thought it
How accurate you think, well, I mean it's just one person, but
Well maybe someone can compare my chapter.
That's a good point.
And what I have to say about at some point in time.
So the emphasis by Kant was trying to make this more
scientific turn, metaphysics into a science, science must have
meant something or I don't, whatever the German word was it even
that word meant something different at that time than now. How is
this new metaphysics that he envisions, how would it be scientific
as opposed what about it is scientific?
Yeah, that's as well a very good point. So the German term is
vision shaft. I don't know if that's helpful.
No, I do remember that.
Ask the question. No, but let me try to explain a bit more
My main question is, I guess is it about the method you use to
arrive at your results? Or is it about scientific means it's
something that the end result is what we can call knowledge? Those
are two options I can see. Because people often, when you hear
science, you immediately hear the word method. And so is he saying
that what's different is that he wants to use a new method? That
was that's where I'm leading.
Yeah. Okay. So I think that's a good point. Yes. And I think
that indeed for Kant the method is really, really very important.
And so I think that we can understand what he means by science and
scientific, if we contrast his own ideas with what he took to be
Wolf's project. So basically the metaphysics that emerged from
Mitch Metaphysics, and that was incredibly influential during the
first half of the 18th century. So seen from Kant's perspective,
Wolf was not able to turn metaphysic into a science for various
reasons. But one of the reasons was that according to Kant, Wolf
did not proceed systematically. So for instance, in Kant's, sorry,
involves general metaphysics, we find a whole list of basic
concepts such as causality and substance and possibility and
necessity and ground and so on. Yes, these well-known concepts now
Kant was not satisfied with this metaphysics because it was just
because Wolf in his view, was just listing these various concepts
but not developing the account in the systematic manner.
And so we can compare these two Kant's own micro system within
the critique of pure that I already mentioned, namely the table of
categories. 12 categories ranged under three, four headings. It
looks really nice and elegant and ant also asserts that the table
of category is developed from a principle. Yeah. He's not very
clear on this. And as well has caused great discussions among his
contemporaries and also later commentators, but at least count
himself held that his table of categories was developed strictly,
systematically. And he thought this was a great improvement
compared to the arbitrary collection of concepts that we find
involves first part of the metaphysics. And so I think that for
Kant's Sentaficity is basically the same as Systematicity. Okay.
That's helpful. And of course, in order to proceed systematically,
you need to have a method that allows you to proceed
So for Kant's, the notion of a science does not necessarily
mean that there has to be a true relationship between my thoughts
and the object of thoughts. So the correspondence theory of truth
is I think irrelevant to Kant's notion of a science or recent
shaft. And of course in the case of particular sciences such as
physics, a lot more is required. According to Kant, physics is only
a true science insofar as it rests on mathematics. So it has to be
able to objectify contents in a scientific manner.
And in the case of physics, it requires the needs to quantify
the findings. And so the physics needs to rely on mathematical
principles in order to be able to quantify its results. But this is
a requirement, this is a requirement in my view that is specific to
physics. It's not a requirement that must be met in all sciences.
And so I think that Kant has a loose notion of science, which
allows him maybe two things, first of all to distinguish as it
were, non-scientific types of metaphysics from a properly
scientific metaphysics. And it also allows him to think about the
specific requirements that must be met in the specific sciences.
Does that make sense?
No. It does, that's helpful. I think one of the things that I
thought was fascinating, and you raised this point in your book is
if it is a method then is critique a method that leads to
scientific results it seems to have here?
I don't know if I summarize that right from your book.
I find this a very interesting and important question. So at
first or at first site, we can say indeed critique leads to the
possibility of developing metaphysics as a science, yes? So it's a
step toward the elaboration of a scientific metaphysics. And as we
just discussed, Kant never really got there, but at least we can
see that this was his project. But then I think the more
interesting part of your question is whether the critique which is
carried out in the critique pre itself, itself already
Because if were, if the critique pre were just the heap of
thoughts or arguments loosely connected together, how can it then
function as a first stepping stone towards a scientific
And how can he criticize Wolf?
Yes. If he cannot meet the requirements of any scientific
endeavor. That he establishes within the critique of, so this is I
think an extremely important question. And what is very interesting
is that Kant's successors, including Maiman and Ryan hold and
Festar and Simone and so on, they all felt that Kant was lacking in
this respect. So they felt that the critique of pure region itself
did not meet its own requirements for scientificity.
And so they challenged Kant in this regards or rejected the
critical reason in some cases, and this allowed them also to
present their own philosophies as an improvement in this regard.
Yes. So for instance, Ronald and Fester, they claimed that Kant was
perfectly right with regard to everything he had said in the
critique reason. However, he had not been able, according to them,
to present his insights in a properly scientific manner. Yes, it
is, to say not in a properly systematic manner.
Yes. Very interesting.
Yeah, no, fascinating.
However, what I am doing at the moment is working on the
question, well is there maybe a certain system to Kant's own
critique of reason.
So is there maybe a certain scientific and systematicity
throughout [inaudible 00:39:28] reason that was not sufficiently
acknowledged by Rhino and Fester and also others. Clearly the
method or the methods that they use to develop their systems is
very different from Kant's, yes? And Fester is the first to
recognize this, but it doesn't mean that there is no systematicity
to the critic reason at all. So I think that what could be done by
commentators today is to try to look at the systematicity that as
it were allowed to organize the various parts of the critique.
Go ahead, sorry about that.
Yes. And I think that this, looking at as it were, the
systematicity of the critique of reason itself requires that we
adopt this rather loose notion of scientificity that I just
mentioned. Because it's clear that otherwise you can only infer
that the critique of your reason is not itself scientific. To think
about a notion of scientificity that can apply both to what Kant
himself does in a critical reason and can also apply to the future
metaphysical system that he had in mind.
Right. Now it's fascinating. And then my synapses are firing
and I have about 75 questions, but unfortunately we're out of time.
Thank you so much. The book is Cons Reform of Metaphysics by Karen
Delore, Cons Reform of Metaphysics, the Critique of Pure Reason
Reconsidered. Look forward to talking to you about that next book.
Thanks very much for talking with me.
Yes, thank you very much for this conversation. And it's true.
I'd like to be re-invited in a couple of years.
Let's do it. Excellent. All right. Thanks very much.