The Critique of Pure Reason quotes

Human reason, in one sphere of its cognition, is called upon to consider questions, which it cannot decline, as they are presented by its own nature, but which it cannot answer, as they transcend every faculty of the mind.

It falls into this difficulty without any fault of its own. It begins with principles, which cannot be dispensed with in the field of experience, and the truth and sufficiency of which are, at the same time, insured by experience.

The arena of these endless contests is called Metaphysic.

Time was, when she was the queen of all the sciences; and, if we take the will for the deed, she certainly deserves, so far as regards the high importance of her object-matter, this title of honour.

Now, it is the fashion of the time to heap contempt and scorn upon her; and the matron mourns, forlorn and forsaken, like Hecuba:

The same would be the case with the other kinds of cognition, if their principles were but firmly established. In the absence of this security, indifference, doubt, and finally, severe criticism are rather signs of a profound habit of thought.

Our age is the age of criticism, to which everything must be subjected.

The sacredness of religion, and the authority of legislation, are by many regarded as grounds of exemption from the examination of this tribunal.

… arrive at these, it must make use of principles which, in fact, extend only to the objects of possible experience, and which cannot be applied to objects beyond this sphere without converting them into phenomena, and thus rendering the practical extension of pure reason impossible.

I must, therefore, abolish knowledge, to make room for belief.

The dogmatism of metaphysics, that is, the presumption that it is possible to advance in metaphysics without previous criticism, is the true source of the unbelief (always dogmatic) which militates against morality.

To these deserving men, who so happily combine profundity of view with a talent for lucid exposition—a talent which I myself am not conscious of possessing—I leave the task of removing any obscurity which may still adhere to the statement of my doctrines.

For, in this case, the danger is not that of being refuted, but of being misunderstood.

For my own part, I must henceforward abstain from controversy, although I shall carefully attend to all suggestions, whether from friends or adversaries, which may be of use in the future elaboration of the system of this Propædeutic.

That all our knowledge begins with experience there can be no doubt.

For how is it possible that the faculty of cognition should be awakened into exercise otherwise than by means of objects which affect our senses, and partly of themselves produce representations, partly rouse our powers of understanding into activity, to compare to connect, or to …

In respect of time, therefore, no knowledge of ours is antecedent to experience, but begins with it.

But, though all our knowledge begins with experience, it by no means follows that all arises out of experience.

For, on the contrary, it is quite possible that our empirical knowledge is a compound of that which we receive through impressions, and that which the faculty of cognition supplies from itself (sensuous impressions giving merely the occasion), an addition which we cannot distinguish from …

for he met with no resistance which might serve him for a support, as it were, whereon to rest, and on which he might apply his powers, in order to let the intellect acquire momentum for its progress.

It is, indeed, the common fate of human reason in speculation, to finish the imposing edifice of thought as rapidly as possible, and then for the first time to begin to examine whether the foundation is a solid one or no.

Arrived at this point, all sorts of excuses are sought after, in order to console us for its want of stability, or rather, indeed, to enable Us to dispense altogether with so late and dangerous an investigation.

Deceived by such a proof of the power of reason, we can perceive no limits to the extension of our knowledge.

The light dove cleaving in free flight the thin air, whose resistance it feels, might imagine that her movements would be far more free and rapid in airless space.

Just in the same way did Plato, abandoning the world of sense because of the narrow limits it sets to the understanding, venture upon the wings of ideas beyond it, into the void space of pure intellect.

Neither of these faculties has a preference over the other. Without the sensuous faculty no object would be given to us, and without the understanding no object would be thought.

Thoughts without content are void; intuitions without conceptions, blind.

Hence it is as necessary for the mind to make its conceptions sensuous (that is, to join to them the object in intuition), as to make its intuitions intelligible (that is, to bring them under conceptions). Neither of these faculties can exchange its proper function.

The definition of the word truth, to wit, “the accordance of the cognition with its object,” is presupposed in the question; but we desire to be told, in the answer to it, what is the universal and secure criterion of the truth of every cognition.

To know what questions we may reasonably propose is in itself a strong evidence of sagacity and intelligence.

For if a question be in itself absurd and unsusceptible of a rational answer, it is attended with the danger—not to mention the shame that falls upon the person who proposes it—of seducing the unguarded listener into making absurd answers, and we are presented with …

Our Consciousness of the one, when we speak of the manifold, is always distinguishable from our consciousness of the other; and it is only respecting the synthesis of this (possible) consciousness that we here treat.

The “I think” must accompany all my representations, for otherwise something would be represented in me which could not be thought; in other words, the representation would either be impossible, or at least be, in relation to me, nothing.

That representation which can be given previously to all thought is called intuition. All the diversity or manifold content of intuition, has, therefore, a necessary relation to the “I think,” in the subject in which this diversity is found.

… priori only by means of categories, and a certain kind and number thereof, is as impossible as to explain why we are endowed with precisely so many functions of judgement and no more, or why time and space are the only forms of our intuition.

To think an object and to cognize an object are by no means the same thing.

In cognition there are two elements: firstly, the conception, whereby an object is cogitated (the category); and, secondly, the intuition, whereby the object is given.

Besides, they often weaken the power of our understanding to apprehend rules or laws in their universality, independently of particular circumstances of experience; and hence, accustom us to employ them more as formulae than as principles.

Examples are thus the go-cart of the judgement, which he who is naturally deficient in that faculty cannot afford to dispense with.

[26] Deficiency in judgement is properly that which is called stupidity; and for such a failing we know no remedy.

[26]

Deficiency in judgement is properly that which is called stupidity; and for such a failing we know no remedy.

A dull or narrow-minded person, to whom nothing is wanting but a proper degree of understanding, may be improved by tuition, even so far as to deserve the epithet of learned.

… indicates a rule, according to which my imagination can delineate the figure of a four-footed animal in general, without being limited to any particular individual form which experience presents to me, or indeed to any possible image that I can represent to myself in concreto.

This schematism of our understanding in regard to phenomena and their mere form, is an art, hidden in the depths of the human soul, whose true modes of action we shall only with difficulty discover and unveil.

Thus much only can we say:

The schema of substance is the permanence of the real in time; that is, the representation of it as a substratum of the empirical determination of time; a substratum which therefore remains, whilst all else changes. (

Time passes not, but in it passes the existence of the changeable.

To time, therefore, which is itself unchangeable and permanent, corresponds that which in the phenomenon is unchangeable in existence, that is, substance, and it is only by it that the succession and coexistence of phenomena can be determined in regard to time.)

… be proved except by means of a deduction of the possibility of experience, it is no wonder that while it has served as the foundation of all experience (for we feel the need of it in empirical cognition), it has never been supported by proof.

A philosopher was asked: “What is the weight of smoke?” He answered: “Subtract from the weight of the burnt wood the weight of the remaining ashes, and you will have the weight of the smoke.”

Thus he presumed it to be incontrovertible that even in fire the matter (substance) does not perish, but that only the form of it undergoes a change. In like manner was the saying:

We have now not only traversed the region of the pure understanding and carefully surveyed every part of it, but we have also measured it, and assigned to everything therein its proper place.

But this land is an island, and enclosed by nature herself within unchangeable limits.

It is the land of truth (an attractive word), surrounded by a wide and stormy ocean, the region of illusion, where many a fog-bank, many an iceberg, seems to the mariner, on his voyage of discovery, a new country, and, while constantly deluding him with …

the former could not, because, if it acts only according to its own laws, the effect (the judgement) must necessarily accord with these laws. But in accordance with the laws of the understanding consists the formal element in all truth.

In the senses there is no judgement—neither a true nor a false one.

But, as we have no source of cognition besides these two, it follows that error is caused solely by the unobserved influence of the sensibility upon the understanding.

Still less must phenomenon and appearance be held to be identical. For truth or illusory appearance does not reside in the object, in so far as it is intuited, but in the judgement upon the object, in so far as it is thought.

It is, therefore, quite correct to say that the senses do not err, not because they always judge correctly, but because they do not judge at all.

Hence truth and error, consequently also, illusory appearance as the cause of error, are only to be found in a judgement, that is, in the relation of an object to our understanding.

A. OF REASON IN GENERAL.

All our knowledge begins with sense, proceeds thence to understanding, and ends with reason, beyond which nothing higher can be discovered in the human mind for elaborating the matter of intuition and subjecting it to the highest unity of thought.

At this stage of our inquiry it is my duty to give an explanation of this, the highest faculty of cognition, and I confess I find myself here in some difficulty.

And thus the practical idea is always in the highest degree fruitful, and in relation to real actions indispensably necessary.

In the idea, pure reason possesses even causality and the power of producing that which its conception contains.

Hence we cannot say of wisdom, in a disparaging way, “it is only an idea.”

… are, as regards their result, rather to be termed sophisms than syllogisms, although indeed, as regards their origin, they are very well entitled to the latter name, inasmuch as they are not fictions or accidental products of reason, but are necessitated by its very nature.

They are sophisms, not of men, but of pure reason herself, from which the Wisest cannot free himself.

After long labour he may be able to guard against the error, but he can never be thoroughly rid of the illusion which continually mocks and misleads him.

They are sophisms, not of men, but of pure reason herself, from which the Wisest cannot free himself.

After long labour he may be able to guard against the error, but he can never be thoroughly rid of the illusion which continually mocks and misleads him.

Of these dialectical arguments there are three kinds, corresponding to the number of the ideas which their conclusions present.

… a discipline, which sets impassable limits to speculative reason in this region of thought, to prevent it, on the one hand, from throwing itself into the arms of a soulless materialism, and, on the other, from losing itself in the mazes of a baseless spiritualism.

It teaches us to consider this refusal of our reason to give any satisfactory answer to questions which reach beyond the limits of this our human life, as a hint to abandon fruitless speculation

; and to direct, to a practical use, our knowledge of ourselves—which, although applicable only to objects of experience, receives its principles from a higher source, and regulates its procedure as if our destiny reached far beyond the boundaries of experience and life.

As impartial umpires, we must lay aside entirely the consideration whether the combatants are fighting for the right or for the wrong side, for the true or for the false, and allow the combat to be first decided.

Perhaps, after they have wearied more than injured each other, they will discover the nothingness of their cause of quarrel and part good friends.

This method of watching, or rather of originating, a conflict of assertions, not for the purpose of finally deciding in favour of either side, but to discover whether the object of the struggle is not a mere illusion, which each strives in vain to reach, …

We have, therefore, nothing but nature to which we must look for connection and order in cosmical events.

Freedom—independence of the laws of nature—is certainly a deliverance from restraint, but it is also a relinquishing of the guidance of law and rule.

For it cannot be alleged that, instead of the laws of nature, laws of freedom may be introduced into the causality of the course of nature. For, if freedom were determined according to laws, it would be no longer freedom, but merely nature.

… world of sense) cannot conclude with an empirically unconditioned condition, and that the cosmological argument from the contingency of the cosmical state—a contingency alleged to arise from change—does not justify us in accepting a first cause, that is, a prime originator of the cosmical series.

The reader will observe in this antinomy a very remarkable contrast.

The very same grounds of proof which established in the thesis the existence of a supreme being, demonstrated in the antithesis—and with equal strictness—the non-existence of such a being.

and that she thus encourages philosophy to extend the province of reason beyond all experience, and at the same time provides it with the most excellent materials for supporting its investigations, in so far as their nature admits, by adequate and accordant intuitions.

Unfortunately for speculation—but perhaps fortunately for the practical interests of humanity—reason, in the midst of her highest anticipations, finds herself hemmed in by a press of opposite and contradictory conclusions, from which neither her honour nor her safety will permit her to draw back.

Nor can she regard these conflicting trains of reasoning with indifference as mere passages at arms, still less can she command peace; for in the subject of the conflict she has a deep interest.

while, in the observation and investigation of nature, it would be forced to remain dumb and to confess its utter ignorance.

Thus indolence and vanity form of themselves strong recommendations of these principles.

Besides, although it is a hard thing for a philosopher to assume a principle, of which he can give to himself no reasonable account, and still more to employ conceptions, the objective reality of which cannot be established, nothing is more usual with the common …

and, however prejudicial it may be to the highest practical principles, there is no fear that it will ever pass the limits of the schools, or acquire any favour or influence in society or with the multitude.

Human reason is by nature architectonic.

That is to say, it regards all cognitions as parts of a possible system, and hence accepts only such principles as at least do not incapacitate a cognition to which we may have attained from being placed along with others in a general system.

such a person, on the supposition that he knew no other way out of the confusion than to settle the truth of one or other of the conflicting doctrines, would live in a state of continual hesitation.

Today, he would feel convinced that the human will is free; to-morrow, considering the indissoluble chain of nature, he would look on freedom as a mere illusion and declare nature to be all-in-all.

But, if he were called to action, the play of the merely speculative reason would disappear like the shapes of a dream, and practical interest would dictate his choice of principles.

Among the trivial subjects of discussion in the old schools of dialectics was this question: “

If a ball cannot pass through a hole, shall we say that the ball is too large or the hole too small?

” In this case it is indifferent what expression we employ; for we do not know which exists for the sake of the other. On the other hand, we cannot say: “The man is too long for his coat”; but:

because, as a series of subordinate representations, it subsists only in the dynamical regress and cannot be regarded as existing previously to this regress, or as a self-subsistent series of things.

Thus the antinomy of pure reason in its cosmological ideas disappears.

For the above demonstration has established the fact that it is merely the product of a dialectical and illusory opposition, which arises from the application of the idea of absolute totality—admissible only as a condition of things in themselves—to phenomena, which exist only in our …

The words I ought express a species of necessity, and imply a connection with grounds which nature does not and cannot present to the mind of man.

Understanding knows nothing in nature but that which is, or has been, or will be.

It would be absurd to say that anything in nature ought to be other than it is in the relations of time in which it stands; indeed, the ought, when we consider merely the course of nature, has neither application nor meaning.

Now a negation cannot be cogitated as determined, without cogitating at the same time the opposite affirmation.

The man born blind has not the least notion of darkness, because he has none of light; the vagabond knows nothing of poverty, because he has never known what it is to be in comfort;[65] the ignorant man has no conception of his ignorance, because he has no conception of knowledge.

All conceptions of negatives are accordingly derived or deduced conceptions; and realities contain the data, and, so to speak, the material or transcendental content of the possibility and complete determination of all things.

for logic pays no regard to the content of a judgement. But the determination of a conception is a predicate, which adds to and enlarges the conception. It must not, therefore, be contained in the conception.

Being is evidently not a real predicate, that is, a conception of something which is added to the conception of some other thing.

It is merely the positing of a thing, or of certain determinations in it. Logically, it is merely the copula of a judgement. The proposition, God is omnipotent, contains two conceptions, which have a certain object or content;

and there is no addition made to the conception, which expresses merely the possibility of the object, by my cogitating the object—in the expression, it is—as absolutely given or existing. Thus the real contains no more than the possible.

A hundred real dollars contain no more than a hundred possible dollars.

For, as the latter indicate the conception, and the former the object, on the supposition that the content of the former was greater than that of the latter, my conception would not be an expression of the whole object, and would consequently be an inadequate …

But both attempts are equally beyond our power—we find it impossible to satisfy the understanding upon this point, and as impossible to induce it to remain at rest in relation to this incapacity.

Unconditioned necessity, which, as the ultimate support and stay of all existing things, is an indispensable requirement of the mind, is an abyss on the verge of which human reason trembles in dismay.

Even the idea of eternity, terrible and sublime as it is, as depicted by Haller, does not produce upon the mental vision such a feeling of awe and terror; for, although it measures the duration of things, it does not support them.

and, still advancing, proceed from the conception of the absolute necessity of the first cause to the completely determined or determining conception thereof—the conception of an all-embracing reality.

Thus the physico-theological, failing in its undertaking, recurs in its embarrassment to the cosmological argument

; and, as this is merely the ontological argument in disguise, it executes its design solely by the aid of pure reason, although it at first professed to have no connection with this faculty and to base its entire procedure upon experience alone.

Now, if I grant that they cannot be employed in the sphere of experience, as constitutive principles, how shall I secure for them employment and objective validity as regulative principles, and in what way can they be so employed?

The understanding is the object of reason, as sensibility is the object of the understanding.

The production of systematic unity in all the empirical operations of the understanding is the proper occupation of reason; just as it is the business of the understanding to connect the various content of phenomena by means of conceptions, and subject them to empirical laws.

But, on the other hand, if misunderstood and employed as constitutive principles of transcendent cognition, they become the parents of illusions and contradictions, while pretending to introduce us to new regions of knowledge.

Thus all human cognition begins with intuitions, proceeds from thence to conceptions, and ends with ideas.

Although it possesses, in relation to all three elements, à priori sources of cognition, which seemed to transcend the limits of all experience, a thoroughgoing criticism demonstrates that speculative reason can never, by the aid of these elements, pass the bounds of possible experience, and …

For this reason, too, negative propositions, which are framed for the purpose of correcting false cognitions where error is absolutely impossible, are undoubtedly true, but inane and senseless; that is, they are in reality purposeless and, for this reason, often very ridiculous.

Such is the proposition of the schoolman that Alexander could not have subdued any countries without an army.

But where the limits of our possible cognition are very much contracted, the attraction to new fields of knowledge great, the illusions to which the mind is subject of the most deceptive character, and the evil consequences of error of no inconsiderable magnitude—the negative element …

The science of mathematics presents the most brilliant example of the extension of the sphere of pure reason without the aid of experience.

Examples are always contagious; and they exert an especial influence on the same faculty, which naturally flatters itself that it will have the same good fortune in other case as fell to its lot in one fortunate instance.

Hence pure reason hopes to be able to extend its empire in the transcendental sphere with equal success and security, especially when it applies the same method which was attended with such brilliant results in the science of mathematics.

… proper place for discussing the peculiar method of transcendental philosophy, as our present task is simply to examine whether our faculties are capable of erecting an edifice on the basis of pure reason, and how far they may proceed with the materials at their command.

Reason must be subject, in all its operations, to criticism, which must always be permitted to exercise its functions without restraint; otherwise its interests are imperilled and its influence obnoxious to suspicion.

There is nothing, however useful, however sacred it may be, that can claim exemption from the searching examination of this supreme tribunal, which has no respect of persons. The very existence of reason depends upon this freedom;

The question here is not whether its own statements may not also be false; it merely regards the fact that reason proves that the opposite cannot be established with demonstrative certainty, nor even asserted with a higher degree of probability.

Reason does not hold her possessions upon sufferance; for, although she cannot show a perfectly satisfactory title to them, no one can prove that she is not the rightful possessor.

It is a melancholy reflection that reason, in its highest exercise, falls into an antithetic; and that the supreme tribunal for the settlement of differences should not be at union with itself.

This consideration restores to Reason her courage; for what source of confidence could be found, if she, whose vocation it is to destroy error, were at variance with herself and without any reasonable hope of ever reaching a state of permanent repose?

Everything in nature is good for some purpose. Even poisons are serviceable; they destroy the evil effects of other poisons generated in our system, and must always find a place in every complete pharmacopoeia.

The objections raised against the fallacies and sophistries of speculative reason, are objections given by the nature of this reason itself, and must therefore have a destination and purpose which can only be for the good of humanity.

… of joining the combatants, it is your part to be a tranquil spectator of the struggle—a laborious struggle for the parties engaged, but attended, in its progress as well as in its result, with the most advantageous consequences for the interests of thought and knowledge.

It is absurd to expect to be enlightened by Reason, and at the same time to prescribe to her what side of the question she must adopt.

Moreover, reason is sufficiently held in check by its own power, the limits imposed on it by its own nature are sufficient;

If we could reckon with security even upon so little, the conflict of speculative reason regarding the important questions of God, immortality, and freedom, would have been either decided long ago, or would very soon be brought to a conclusion.

But, in general, the uprightness of the defence stands in an inverse ratio to the goodness of the cause; and perhaps more honesty and fairness are shown by those who deny than by those who uphold these doctrines.

I shall persuade myself, then, that I have readers who do not wish to see a righteous cause defended by unfair arguments.

… the good cause by illusory arguments, rather than to give to our supposed opponents the advantage of lowering our declarations to the moderate tone of a merely practical conviction, and of compelling us to confess our inability to attain to apodeictic certainty in speculative subjects.

But we ought to reflect that there is nothing, in the world more fatal to the maintenance of a good cause than deceit, misrepresentation, and falsehood.

That the strictest laws of honesty should be observed in the discussion of a purely speculative subject is the least requirement that can be made.

for it is not involved in these disputes, which have an immediate relation to certain objects and not to the laws of the mind, but is instituted for the purpose of determining the rights and limits of reason.

Without the control of criticism, reason is, as it were, in a state of nature, and can only establish its claims and assertions by war.

Criticism, on the contrary, deciding all questions according to the fundamental laws of its own institution, secures to us the peace of law and order, and enables us to discuss all differences in the more tranquil manner of a legal process.

There is, accordingly, no proper polemic in the sphere of pure reason. Both parties beat the air and fight with their own shadows, as they pass beyond the limits of nature, and can find no tangible point of attack—no firm footing for their dogmatical conflict.

Fight as vigorously as they may, the shadows which they hew down, immediately start up again, like the heroes in Walhalla, and renew the bloodless and unceasing contest.

But neither can we admit that there is any proper sceptical employment of pure reason, such as might be based upon the principle of neutrality in all speculative disputes.

There is, accordingly, no proper polemic in the sphere of pure reason.

Both parties beat the air and fight with their own shadows, as they pass beyond the limits of nature, and can find no tangible point of attack—no firm footing for their dogmatical conflict.

Fight as vigorously as they may, the shadows which they hew down, immediately start up again, like the heroes in Walhalla, and renew the bloodless and unceasing contest.

The difficulties and objections we have to fear lie in ourselves. They are like old but never superannuated claims; and we must seek them out, and settle them once and for ever, if we are to expect a permanent peace.

External tranquility is hollow and unreal.

The root of these contradictions, which lies in the nature of human reason, must be destroyed;

This caution serves to simplify very much the criticism of all propositions of reason. When reason employs conceptions alone, only one proof of its thesis is possible, if any.

When, therefore, the dogmatist advances with ten arguments in favour of a proposition, we may be sure that not one of them is conclusive.

For if he possessed one which proved the proposition he brings forward to demonstration—as must always be the case with the propositions of pure reason—what need is there for any more?

The bounds, moreover, which it is forced to set to its speculative exercise, form likewise a check upon the fallacious pretensions of opponents; and thus what remains of its possessions, after these exaggerated claims have been disallowed, is secure from attack or usurpation.

The greatest, and perhaps the only, use of all philosophy of pure reason is, accordingly, of a purely negative character.

It is not an organon for the extension, but a discipline for the determination, of the limits of its exercise; and without laying claim to the discovery of new truth, it has the modest merit of guarding against error.

and thus what remains of its possessions, after these exaggerated claims have been disallowed, is secure from attack or usurpation. The greatest, and perhaps the only, use of all philosophy of pure reason is, accordingly, of a purely negative character.

It is not an organon for the extension, but a discipline for the determination, of the limits of its exercise; and without laying claim to the discovery of new truth, it has the modest merit of guarding against error.

At the same time, there must be some source of positive cognitions which belong to the domain of pure reason and which become the causes of error only from our mistaking their true character, while they form the goal towards which reason continually strives.

The practical law based on the motive of happiness I term a pragmatical law (or prudential rule); but that law, assuming such to exist, which has no other motive than the worthiness of being happy, I term a moral or ethical law.

The first tells us what we have to do, if we wish to become possessed of happiness; the second dictates how we ought to act, in order to deserve happiness.

The first is based upon empirical principles; for it is only by experience that I can learn either what inclinations exist which desire satisfaction, or what are the natural means of satisfying them.

… its practical use—and to a corpus mysticum of rational beings in it, in so far as the liberum arbitrium of the individual is placed, under and by virtue of moral laws, in complete systematic unity both with itself and with the freedom of all others.

That is the answer to the first of the two questions of pure reason which relate to its practical interest: Do that which will render thee worthy of happiness.

The second question is this: If I conduct myself so as not to be unworthy of happiness, may I hope thereby to obtain happiness?

For they do not satisfy all the aims which are natural to every rational being, and which are determined à priori by pure reason itself, and necessary.

Happiness alone is, in the view of reason, far from being the complete good.

Reason does not approve of it (however much inclination may desire it), except as united with desert. On the other hand, morality alone, and with it, mere desert, is likewise far from being the complete good.

I can only maintain, that is, affirm as necessarily valid for every one, that which produces conviction.

Persuasion I may keep for myself, if it is agreeable to me; but I cannot, and ought not, to attempt to impose it as binding upon others.

Holding for true, or the subjective validity of a judgement in relation to conviction (which is, at the same time, objectively valid), has the three following degrees: opinion, belief, and knowledge. Opinion is a consciously insufficient judgement, subjectively as well as objectively.

Holding for true, or the subjective validity of a judgement in relation to conviction (which is, at the same time, objectively valid), has the three following degrees: opinion, belief, and knowledge.

Opinion is a consciously insufficient judgement, subjectively as well as objectively. Belief is subjectively sufficient, but is recognized as being objectively insufficient. Knowledge is both subjectively and objectively sufficient.

Subjective sufficiency is termed conviction (for myself); objective sufficiency is termed certainty (for all). I need not dwell longer on the explanation of such simple conceptions.

we must know, or abstain from forming a judgement altogether. The case is the same with the maxims of morality. For we must not hazard an action on the mere opinion that it is allowed, but we must know it to be so.

In the transcendental sphere of reason, on the other hand, the term opinion is too weak, while the word knowledge is too strong.

From the merely speculative point of view, therefore, we cannot form a judgement at all.