THE LIMITS OF SENSE AND REASON: A Line-By-Line Critical Commentary on Kant’s “Critique of Pure Reason,” #7.
By Robert Hanna
[I] was then making plans for a work that might perhaps have the title, “The Limits of Sense and Reason.” I planned to have it consist of two parts, a theoretical and a practical. The first part would have two sections, (1) general phenomenology and (2) metaphysics, but this only with regard to its method. (Letter to Marcus Herz, 21 February 1772 [C 10: 129])
The first five installments in this series followed the 2019–2020 version of THE LIMITS OF SENSE AND REASON, aka LSR.
Starting with installment #6, subsequent installments follow the revised and updated 2021 version of LSR.
In any case, you can read or download a .pdf of the complete text of the 2021 version of LSR HERE.
Because LSR is an ongoing and indeed infinite task, revised and updated .pdfs of the complete text will be uploaded to that URL on a regular basis.
CPR TEXT Axii-xiv/GW101–102 Preface to the First (A) Edition
Axii Yet by this I do not understand a critique of books systems, but a critique of the faculty of reason in general, in respect of all the cognitions after which reasonb might strive independently of all experience, and hence the decision about the possibility or impossibility of a metaphysics in general, and the determination of its sources, as well as its extent and boundaries, all, however, from principles.c
It is on this path, the only one left, that I have set forth, and I flatter myself that in following it I have succeeded in removing all those errors that have so far put reason into dissension with itself in its nonexperiential use. I have not avoided reason’s questions by pleading incapacity of human reason as an excuse; rather I have completely specified these questions according to principles,d and after discovering the point where reason has misunderstood itself, I have resolved them to Axiii reason’s full satisfaction. To be sure, the anwer to these questions has not turned out just as dogmatically enthusiastic lust for knowledge might have expected; for the latter could not be satisfied except through magical powers in which I am not an expert. Yet this was also not the intent of our reason’s natural vocation; and the duty of philosophy was to abolish the semblance arising from misinterpretation, even if many and beloved delusions have to be destroyed in the process. In this business I have made comprehensiveness my chief aim in view, and I make bold to say that there cannot be a single metaphysical problem that has not been solved here, or at least to the solution of which the key has not been provided. In fact pure reason is such a perfect unity that if its principlee were insufficient for even a single one of the questions that are set
a Selbsterkenntnis b sie To agree with “faculty of reason” (das Vernunftsvermögen) the pronoun should have been neuter; perhaps Kant was taking the antecedent to be “reason” (die Vernunft). c Principien d Principien e Princip
for it by its own nature, then this [principle] might as well be discarded, because then it also not be up to answering any of the other questions with complete reliability.
While I am saying this I believe I perceive in the Axiv face of the reader an indignation mixed with contempt at claims that are apparently so pretentious and immodest; and yet they are incomparably more moderate than those of any author of the commonest program who pretends to prove the simple nature of the soul or the necessity of a first beginning of the world. For such an author pledges himself to extend human cognition beyond bounds of possible experience, of which I humbly admit that this wholly surpasses my capacity; instead I have to do merely with reason itself and its pure thinking; to gain exhaustive acquaintance with them I need not seek far beyond myself, because it is in myself that I encounter them, and common logic already also gives me an example of how the simple acts of reason may be fully and systematically enumerated; only here the question is raised how much I may hope to settle with these simple acts if all the material and assistance of experience are taken away from me.
So much for the completeness in reaching each of the ends, and for the comprehensiveness in reaching all of them together, which ends are not proposed arbitrarily, but are set up for us by the nature of cognition itself, as the matter of our critical investigation.
At this point, Kant makes five notoriously strong claims on behalf of his revolutionary philosophical project, the critique of pure reason, and also on behalf of his big book, the CPR,alike.
First, this is the only philosophical method by which classical Rationalist metaphysics can be adequately analyzed and criticized.
Second, in this book he’s completely avoided the mistakes by which non-experiential human reason falls forever into cognitive inauthenticity or commits cognitive suicide.
Third, he’s completely spelled out the questions, mentioned in the first paragraph of the Preface, which human reason puts to itself and cannot answer when it is being deployed non-experientially, according to principles.
Fourth, he’s answered these questions “to reason’s full satisfaction.”
Fifth and finally, his chief aim has been a synoptic understanding of human reason, and correspondingly he’s solved all the basic problems of classical Rationalist metaphysics.
On the face of it, this is sheer philosophical arrogance and an unintentional, self-deceptive backslide into the very same sort of dogmatic classical metaphysical and especially classical Rationalist philosophy that Kant intends to be diagnosing and revolutionizing; and if so, then Kant’s assertions are nothing but what his contemporary William Blake brilliantly identified as the voice of “mind-forg’d manacles”:
In every cry of every Man,
In every Infants cry of fear,
In every voice: in every ban,
The mind-forg’d manacles I hear.[i]
But, leaving aside the issue about philosophical arrogance — often enough, one philosopher’s arrogance is just another’s justified self-confidence — at the very least, Kant is fully aware of the worry about self-deceptive backliding into classical metaphysical dogmatism, especially into classical Rationalist dogmatism, and he has two pre-emptive responses to it.
First, the structure of human reason in its non-experiential use (aka “pure reason”) is not only inherently hierarchical, or multi-level: it is also inherently holistic: “a perfect unity.”
Its internal structure is therefore such that, on the one hand, no one of its principles could be correct without all of its principles also being correct, and on the other hand,
no one of its basic problems can be solved without also solving all of them.
So assuming that the critique of pure reason yields even one positive result, then it also suffices to yield a complete set of such results.
Again, as Gödel showed formally and rigorously in 1931, but as Kant importantly anticipates in 1781, an inference from systematicity to completeness is sound when and only when a system’s ground of truth is explicitly outside that system and also constrains the ontic and semantic scope of that system in a well-founded way that inherently heeds the fundamental ontological difference between phenomena and noumena.
Second, as we’ve already seen, all the self-inflicted problems of classical metaphysics and especially Rationalist metaphysics stem from a single source, namely, vicious impredicative reasoning, and its attempt — inevitably leading to absolute, ill-founded, noumenal sets or totalities, and antinomies/paradoxes/hyper-contradictions/ dialetheias — to apply rational principles that are adequately legitimated by human experience, beyond the limits of human experience.
But the critique of pure reason is based entirely and explicitly on its rational human rejection of vicious impredicative reasoning, and also on its rational human resolution to pursue the process of psycho-metaphilosophically diagnosing and studying, step-by-step, the way in which a reflectively immature and unenlightended (that is, unselfcritical and unCritical) human reason can thereby tragically self-destruct.
So, says Kant, it can’t (kant) possibly be the case that the critique of pure reason has committed the very same error that it was originally set up to detect and rectify.
On the basis of these two responses, Kant also says that he’s sufficiently warranted in concluding that he has established the primitive content of the critique of pure reason, not only as to its basic ends or purposes and the exhaustive articulation of each member of this set of ends, but also as to the comprehensiveness of the total set of ends.
These, he thinks, are a mirror of the internal constitution of the human cognitive faculty.
Now in the course of formulating these responses and then drawing this very strong conclusion, Kant provides two other reasons for holding that the critique of pure reason is inherently more reliable than and essentially distinct from the sort of classical metaphysical and especially classical Rationalist metaphysical reasoning that purports to prove, for example, the simplicity of the soul, or the thesis that the world necessarily has a first cause, namely:
I have merely to do with reason itself and its pure thinking; to gain exhaustive acquaintance with them I need not seek far beyond myself, because it is in myself that I encounter them, and general logic (gemeine Logik) also already gives me an example of how the simple acts of reason may be fully and systematically enumerated; only here the question is raised how much I may hope to settle with these simple acts if all the material and assistance of experience are taken away from me. (CPR Axiv)
In other words,
(i) the critique of pure reason bases its claims on rational self-reflection or rational introspection, not on claims about anything outside the self, and
(ii) the critique of pure reason presupposes, as a fundamental guide, the complete analysis of reason’s “simple acts” that can be found in what Kant later calls pure general logic.
It’s clear, then, that Kant is making two crucial assumptions here:
(i*) that the representational content, formal structure, and intentional activity of reason is veridically accessible to reason itself by means of self-reflection or introspection (The Reflexive Transparency Assumption), and
(ii*) that pure general logic lays bare the complete formal structure of human theoretical rationality itself, and is both explanatorily and justificationally presupposed by every other science, including metaphysics, mathematics, natural science or physics, and every other kind of logic (The Pure General Logic Assumption).
The second assumption, in order to be properly understood, requires some preliminary definitions, which I will also look at in more detail when we get to the Analytic of Concepts.
For Kant, logic is the categorically normative, strictly universal, law-governed a priori science of the laws of thought — the complete set of rules or principles specifying how rational human animals ought to think, in order to conform to the highest or supreme standards of human reason itself.
Analytic logic is the categorically normative, strictly universal, law-governed a priori science of consistent thinking, conceptually necessary truth, and valid inference (aka logical consequence).
Dialectical logic is the categorically normative, strictly universal, law-governed a priori science of inconsistent thinking, falsity or illusion, and fallacy (aka invalidity or non-consequence).
Pure logic is absolutely non-empirical logic, whether analytic or dialectical.
Applied logic is logic, whether analytic or dialectical, under actual, empirical conditions of thinking, namely, the empirical psychology of logic.
General logic is logic, whether analytic or dialectical, whose consistency/inconsistency, conceptually necessary truth/falsity or illusion, and validity/fallacy does not metaphysically depend on, and therefore is not necessarily determined by, the comprehensions or Umfangen of objects or states of affairs to which logic applies.
And particular or special logic is logic, whether analytic or dialectical, whose consistency/inconsistency, conceptual necessary truth/falsity or illusion, and validity/fallacy does metaphysically depend on, and therefore is necessarily determined by, the comprehensions of objects or states of affairs to which logic applies.
It’s often asserted that Kant’s notion of logical generality implies the necessary exclusion of and systematic insensitivity to existential commitment and existentially-committed singular terms in his analytic a priori general logic — therefore, that Kant is committed to the “topic-neutrality” of pure logic.
But that’s a big mistake, since for Kant “If Socrates is a bachelor, then Socrates is a bachelor” is every bit as logically true and analytic a priori as “All bachelors are bachelors.”
And, like Aristotle, Kant also holds that the antecedents of all propositions of the form “All Fs are Gs” — namely, “A” propositions in the Aristotelian Square of Opposition — are existentially-committed.
So the a priori general logical analyticity of “All bachelors are bachelors” for Kant is perfectly consistent with that proposition’s semantic commitment to the existence of some bachelors.
In fact, it’s only Bolzano in his Theory of Science — and later Frege, as well as Russell, and Carnap (in Logical Syntax of Language, although matters are more complicated in Meaning and Necessity), all implicitly following Bolzano on this point — who necessarily exclude existential commitment and existentially committed singular terms from a priori logical generality and analyticity.[ii]
Necessary underdetermination by conceptual or singular referential comprehension is one thing, and the necessary exclusion of and systematic insensitivity to existential commitment and genuine singular reference — the supposed topic-neutrality of pure logic — is quite another.
For Kant only the former is required for a priori logical generality and analyticity, not the latter.
In this respect, Kant’s view of pure logic is actually much closer in spirit to Tarski’s model-theoretic semantic approach to pure logic, and to Quine’s appeals to “obviousness” and “sheer logic” in his Philosophy of Logic, than it is to Frege’s, Russell’s, or the Logical Syntax of Language-era Carnap’s foundational approaches.[iii]
In any case, the topic-neutrality of pure logic is indeed directly entailed by logical platonism and logical conventionalism/stipulationism alike, and these binary foundational options have ideologically dominated mainstream philosophical work on the metaphysical and epistemic foundations of logic ever since Frege.
Nevertheless, the hegemony of these binary options is philosophically misguided.
The Kantian position on the metaphysical and epistemic foundations of logic is essentially and importantly distinct from logical platonism and logical conventionalism/stipulationism alike, and therefore constitutes a distinctively third option.[iv]
In particular, for Kant,pure logic is inherently topic–underdetermined or topic-synoptic, not topic-neutral.
This in turn allows Kant’s logic to remain fully general while also fully allowing for existential commitment and a robust, actual-world-indexed semantics of singular terms, general terms, and synthetic a posteriori and a priori judgments/propositions, all ranging over experienceable worlds.
In this way, for Kant pure general logic is the absolutely non-empirical, categorically normative, strictly universal, law-governed a priori science of the laws of thought, whether analytic or dialectical, whose consistency/inconsistency, conceptual necessary truth/falsity or illusion, and validity/fallacy does not metaphysically depend on, and therefore is necessarily underdetermined by, and synoptic over, all the comprehensions of objects or states of affairs to which pure general logic applies.
So it’s precisely this science of pure general logic, Kant is assuming via The Pure General Logic Assumption, that lays bare the complete formal structure of human theoretical rationality itself, and is both explanatorily and justificationally presupposed by every other science, including metaphysics, mathematics, natural science or physics, and every other kind of logic.
Now on the one hand, if there are any good reasons for seriously doubting either of these two crucial assumptions, then Kant’s project is correspondingly in serious trouble.
More specifically, can Pyrrhonian skepticism be effectively applied to either The Reflexive Transparency Assumption or the The Pure General Logic Assumption?
If so, then the critique of pure reason goes down in flames, and so does human rationality itself.
But on the other hand, if Kant is able to provide sufficiently good reasons for making these assumptions, and if he’s able to respond effectively to Pyrrhonian skepticism about either rational self-reflection or pure general logic, then the critique of pure reason is commensurately fireproofed and firewalled, and so is human rationality.
So I’ll flag The Reflexive Transparency Assumption and The Pure General Logic Assumption alike for later close critical examination.
[i] W. Blake, “London,” in W. Blake, Songs of Experience (1794), lines 5–8.
[ii] See, e.g., R. Hanna, “What is a ‘Representation-in-Itself’? Kant, Bolzano, and Anti-Psychologism,” available online at URL = <https://www.academia.edu/13452551/What_is_a_Representation-in-Itself_Kant_Bolzano_and_Anti-Psychologism>.
[iii] For the long version of this story, see R. Hanna, Cognition, Content and the A Priori: A Study in the Philosophy of Mind and Knowledge (THE RATIONAL HUMAN CONDITION, Vol. 5) (New York: Nova Science, 2018), also available online in preview HERE, chs. 4–5.
[iv] See, e.g., R. Hanna, “Jäsche Logic,” in J. Wuerth (ed.), Cambridge Kant Lexicon (Cambridge: Cambridge Univ. Press, 2021), pp. 707–711, also available online in preview HERE; and R. Hanna, Rationality and Logic (Cambridge, MA: MIT Press, 2006), also available online in preview HERE.
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