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53Issue IX ɢ Spring 2022

The Nature of Human Knowledge

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THE NATURE OF HUMAN KNOWLEDGE
in Light of Empiricism After a Critique of Kantian 

Epistemology
 BURAK ARICI

It is generally thought that humans, by nature, have a tendency to question and 
know. We never feel satis!ed with the amount of knowledge we have, but rather, 

always seek more, wholeheartedly believing that knowledge is power. Although we 
think that knowledge is exceptionally valuable, do we really examine the nature or real 
source of this power? Discourse concerning the nature of knowledge has pervaded the 
history of philosophy. One of the conspicuous investigations of this inquiry is related 
to the origins of knowledge; how do we acquire, constitute, or reach knowledge? It 
can be said that there are two main epistemological approaches that try to give an 
answer to questions of how we really know: rationalism and empiricism. "e former, 
essentially, claims that knowledge derives from reason and that through the use of 
reason, we can directly comprehend certain truths such as logic, mathematics, ethics, 
and metaphysics. "e latter, in contrast, suggests that the source of knowledge is 
not reason, but sensory experience based on perceptual data. It is not di#cult to 
realize that these two opposite philosophical doctrines pave the way for divergent 
worldviews stemming from  the radical di$erences in  each method’s mechanism for 
the acquisition of knowledge. "ese approaches, on the grounds of their foundational 
attributes, are so in%uential that the divide between them persists in areas outside of 
their original philosophical domain. While a rationalist philosophy can attempt to 
explain logic, mathematics, or metaphysics through the existence of an ideal world



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Dianoia: The Undergraduate Philosophy Journal of Boston College

which is independent of the material world in which we live, an empiricist philosophy 
can try to do this by appealing only to sensory experience. However, how can we know 
which approach is true? Do we have to choose one of them?

§1 An Overview of Kantian Epistemology
Immanuel Kant attempts to solve the problems of knowledge through a synthesis 
of rationalism and empiricism. Rationalism, which neglects the importance of 
sensory data acquired by perceptual observation, gives rise to groundless metaphysical 
conceptions, and that mere empiricism, which underestimates the capacity of reason, 
prevents us from learning any necessary truths about experience. Put simply, he makes 
a distinction between that which we can know and that which we cannot know by 
positing two di$erent realms: the realm of phenomena to which we have access, and 
the realm of noumena (the world of things-in-themselves) to which we do not. Along 
with that, he argues we can only have knowledge of what we can experience in the 
realm of phenomena. Our mind processes information acquired from the external 
world by dint of sensory experience, and this gives it order to provide us the skill of 
comprehension. In parallel, he proposes some general categories by which human 
understanding operates and makes judgments like quantity, quality, relation, and 
modality. While Kant repudiates the idea of obtaining knowledge from the noumenal 
world, “he [holds] that we can discover the essential categories that govern human 
understanding, which are the basis for any possible cognition of phenomena.”1  
Even though he agrees with empiricists that knowledge stems from experience, he 
champions the existence of a priori knowledge that can be reached without experience 
or sense data as opposed to a posteriori knowledge that requires experience to be known. 
Concerning Kant, H. J. Paton elucidates that “We can have [a priori] knowledge by 
means of the categories, only if the categories are due to the nature of the mind and 
are imposed by the mind on the objects which it knows.”2  In other words, it is argued 
that the human mind has attributes that make a priori knowledge possible. In this 
vein Kant makes another distinction in the categorization of knowledge to show how 
di$erent types of knowledge are revealed: the analytic-synthetic distinction.

According to Kant, propositions, similar to the di$erence between a priori and a 
posteriori, can be examined within the analytic-synthetic distinction on the linguistic-
judgmental ground. While analytic propositions are true or not true only by virtue 
of meaning, synthetic propositions are true or not true in their meaning-relation to 
the world. For example, the statement that all bachelors are unmarried demonstrates 
an analytic proposition because we do not have to con!rm, by observing the world, 
that it is the case. Instead, this is necessarily and universally true solely by virtue of the 
meaning of the concepts “bachelor” and “unmarried men.”

1 Amie "omasson, “Categories”, "e Stanford Encyclopedia of Philosophy (Summer 2019 Edition), Edward N. 
Zalta (ed.), URL = <https://plato.stanford.edu/archives/sum2019/entries/categories/>.

2 H. J. Paton, Kant’s Metaphysic of Experience, (London: George Allen and Unwin, 1936), 258.



55Issue IX ɢ Spring 2022

The Nature of Human Knowledge

Quite the contrary, the statement that some bachelors are bald is a synthetic 
proposition since in order to test the veracity of this claim, we need to make some 
observations in the world and see if this is the case.

At this point, it becomes possible to address a conceptual scheme which consists of 
the concepts “a priori, a posteriori, analytic, and synthetic” by their combination in 
the expression of human knowledge. For Kant, propositions like “All bachelors are 
unmarried men” and “All squares have four equal sides” represent analytic a priori 
judgments, because we can know whether or not they are true before experience, and 
it is analytic on the grounds that they are true in virtue of their meanings instead of 
their truth-relations to the world. Analytic a posteriori, on the other hand, establishes 
an empty category. Analyticity is that which implies necessity and universality, 
and posteriority is that which depends on observation and that has the capacity to 
create di$erent possibilities.  "erefore, there is a contradiction between the two 
terms. Synthetic a posteriority refers to observational judgments that can also include 
di$erent possibilities (e.g., the car is red, it is raining). Hence, this category, as the 
exact opposite of analytic a priori, represents the cluster of observations that are not 
necessary and universal. Lastly, synthetic a priority seems contradictory like analytic 
a posteriori, but in Kant’s account of knowledge, it remains  a signi!cant element. 
For him, mathematics and causality, for instance, show synthetic a priori knowledge. 
Consider “7+5=12.” Kant brie%y argues that we cannot regard this equation as 
analytic, since, as he writes in the Prolegomena, “[t]he concept of twelve is in no way 
already thought because I merely think to myself this uni!cation of seven and !ve, 
and I may analyze my concept of such a possible sum for as long as may be, still I will 
not meet with twelve therein” [4:269]. "at is, we cannot think of this proposition 
in the same manner as, say, “All bachelors are unmarried,” because those simply do 
not have the same logical structure in that the concept of bachelor is equivalent to 
the concept of unmarried in terms of meaning, whereas the concept of twelve is 
not equivalent to the concept of the sum of seven and !ve. Rather, we infer twelve 
from the sum of seven and !ve by our empirical intuitions. Other than that, this 
mathematical proposition is a priori for the reason that it is also possible to know the 
proposition independently of experience. Likewise, causality is synthetic a priori in 
that in order to comprehend this phenomenon, we need to !rst experience the cause 
and e$ect relation. Besides, it is a priori for the same reason — it is possible to know 
the proposition independently of experience. Inferring their truth and knowing 
these independently of experience may seem contradictory, but Kant expounds 
this issue by asserting that the human mind operates through categories in relation 
to perceptual data within space and time and makes judgments. "ese judgments 
about mathematics and causality, like any other judgments, are subject to the mind’s 
processes. In other words, the grounds or foundations of synthetic a priori knowledge 
reside in the principles and regulatory structure of the mind. “[T]he concept of cause 
is not empirical but rather a pure category of the understanding, required to make 



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Dianoia: The Undergraduate Philosophy Journal of Boston College

sense of the relation of events within experience.”3  We put the mind into action 
through sensory data in the investigation of the knowledge of reality and in this way, 
we reach the necessary and universal knowledge of the phenomenal world and laws 
of nature. As Kant puts it in Critique of Pure Reason:

“Even laws of nature, if they are considered as principles of the empirical use of the 
understanding, at the same time carry with them an expression of necessity, thus at 
least the presumption of determination by grounds that are a priori and valid prior 
to all experience.”4 

After all, in Kantian epistemology, the obvious synthesis of rationalism and empiricism 
becomes easier to discern by the clari!cation and combination of the concepts “a 
priori, a posteriori, analytic, and synthetic” and in this way, we can understand Kant’s 
suggestion as to how to acquire knowledge and know reality. 

§2 Does Kantian epistemology really work?
It is no question that the Kantian conception of knowledge has attracted many 
philosophers. It has been thought that it provides a consistent and cogent solution 
to the shortcomings of rationalism and empiricism by allowing the existence of 
both “knowledge-before-experience” and “knowledge-after-experience” within a 
conceptualization of the analytic-synthetic dichotomy. Kant’s conception of synthetic 
a priori knowledge, particularly, deserves attention at this point, because he makes 
an extraordinary move in opposition to the classical conception of knowledge at 
his time by introducing synthetic a priority. Before Kant, David Hume, in An 
Enquiry Concerning Human Understanding, claimed that human knowledge 
consists of “relations of ideas” and “matters of fact.” To clarify, “recent Empiricists 
have formulated Hume’s challenge in the a priori–a posteriori, analytic–synthetic 
terminology. "eir position, the modernized version to the extent that it is directly 
inspired by Hume’s doctrine, can be formulated in this way: All knowable propositions 
are either analytic a priori or synthetic a posteriori.”5

"at is, Hume’s understanding of knowledge only consists of analytic a priori and 
synthetic a posteriori, and unlike Kant, excludes synthetic a priori. "e reason that 
Kant’s introduction of synthetic a priori knowledge is of great importance is better 
comprehended through the di$erence between the ways Kant and Hume understand 
laws of nature. In simple terms, according to Kant, by means of observation (not 
being con!ned within meanings or in short, syntheticity), we can discover necessary 

3 Antony Flew, A Dictionary of philosophy, (London: Macmillan, 1979), 102
4 Immanuel Kant, Critique of Pure Reason (Paul Guyer, Allen W. Wood, Trans.),                                                                                                    

(Cambridge, United Kingdom; New York, NY, USA: Cambridge University Press. 1999), [A159].
5 Georges Dicker, Hume's Epistemology and Metaphysics: An Introduction, (London; New York: Routledge. 1998), 

41.



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The Nature of Human Knowledge

and universal phenomena of which we actually have knowledge before experience. 
Yet, Hume argues that it is impossible to reach necessary and universal knowledge of

the world through experience, but rather, the only knowledge that we have through 
experience is synthetic a posteriori in that we observe the world (syntheticity) and reach 
probable knowledge that can be known after experience and that, in principle, has the 
chance to change in lieu of being necessary and universal knowledge. For instance, 
Kant would consider gravity to be synthetic a priori because unlike analytic truths, 
the knowledge of this phenomenon can, !rstly, be learned through experience, and 
then, it can be discerned that gravitational attraction is necessary and universal on 
the grounds that “[gravity] cannot be viewed as simply an [empirical fact] about the 
true motions […] for without this property we are unable to de!ne the true motions 
in the !rst place”6  Hume, quite to the contrary, would regard gravity as simply an 
empirical fact. In other words, the reason that objects fall down to the ground cannot 
be explained through the law of gravitation, but rather, this phenomenon is synthetic 
a posteriori, and there is no rationale to claim that objects will fall down every single 
time necessarily and universally. What makes us think that objects will fall, in fact, 
is not the law of gravitation, but our past experiences: we make generalizations as to 
how nature works by relying upon our past empirical data and apply them to the 
future events. However, Kant, as a response to Hume, holds that it is not the case 
that we cannot reach necessary and universal laws of nature, but instead, we can have 
this knowledge by the active role of human mind in the formation of knowledge: 
as Kant, in the Prolegomena, says, “"e understanding does not draw its (a priori) 
laws from nature, but prescribes them to it.”7  "at is, we have laws of nature in our 
minds before experience, but in order to know or make sense of them, we need to 
experience or see how they work in nature. "is reasoning, at !rst glance, may seem 
quite convincing today,  as we have learned a lot through modern science about how 
human beings perceive and experience the world. We can consider this example: we 
see di$erent colors via certain cells in the eyes that enable us to perceive them. When 
some light waves re%ected from an object come to our eyes, we can see its color if this 
biological system works properly, and this shows, like gravity, a use of laws of nature 
and thus, indicates a priority, necessity, and universality in its epistemic possession. 
In Kantian terms, it could be paraphrased in such a way that even if we did not see 
any object, we would still come to know, owing to the related cells in the eyes, that 
we have the concept of color in our minds, but so as to understand or make sense of 
this concept, we need to see an object: understanding, say, redness becomes possible 
only after seeing a red object. Yet, the question is: how can we really know whether 
we have such a priori concepts, laws, categories, and so on in our minds without 

6 Michael Friedman. “KANT ON SPACE, THE UNDERSTANDING, AND THE LAW OF GRAVITATION: 
‘PROLEGOMENA’ §38.” "e Monist 72, no. 2 (1989), 243.

7 Immanuel Kant, Prolegomena to any future metaphysics that will be able to come forward  as science: with selections 
from the Critique of pure reason (Gary Hat!eld, Trans.). (Cambridge, UK; New York: Cambridge University 
Press, 2004), [4:320]



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Dianoia: The Undergraduate Philosophy Journal of Boston College

assuming their presence? If our genes or physiological systems are di$erent names for 
those, then this claim is absolutely true, but at this point, that which is implicated, 
in fact, is that we already have the knowledge of colors (or other a priori laws and 
principles), but we simply do not understand those before experience. A color-blind 
person cannot see some colors as a person who is not color-blind can see. Does 
it mean that color-blind people have the de!ciency of some inherent concepts in 
their minds? "e Kantian answer could be that they do not have such a de!ciency, 
but nevertheless, they cannot comprehend or make sense of colors as non-color-
blind people can do due to the fact that they do not possess adequate and propitious 
biological equipment that enables them to catch the required sensory data. "e same 
question arises once again: what is the rationale behind assuming the pre-existence of 
such concepts? Our biological instruments, surely, play a signi!cant role in what we 
understand and how we experience the world in accordance with our development 
and adaptation in the evolutionary history of humankind. In parallel, our genes 
can provide us the opportunity to know or experience certain kinds of things in 
the world as discussed in the example where we can see redness through particular 
cells, but does carrying certain genes mean that we have the knowledge of what 
these genes carry? What is knowledge, then? Our congenital tendency or capacity 
to walk, for instance, does not express that we have a priori knowledge of walking 
even before starting to walk, but rather, it only shows that our biology enables us to 
act in such a way. "us, we can say that our genes or physiological systems are not 
concepts, categories, or knowledge, but our equipment to have knowledge, because 
knowing that we can walk or understanding redness is a conscious phenomenon 
of which we become aware through establishing beliefs about ourselves. or the 
world by means of observation. What Kant means here is the existence of such a 
framework consisting of a priori concepts, categories, and so on from the abstract 
and rationalist standpoint, but the proposal of such a framework, in fact, implies 
a groundless metaphysical assertion, since how can we claim, for example, that a 
color-blind person has the concept of redness, or that a healthy person who has been 
unconscious since his or her birth and who has no experience about the world has 
such a structure in the mind? Alternatively, claiming that making such abstractions 
and creating concepts or categories after experience is much more compatible with 
our knowledge about ourselves and the world, and seeing that becomes easier when 
we test the compatibility between so-called a priori knowledge and what we see when 
we look at the world.

Kant’s proposal of synthetic a priori, in this way, comes together with such criticisms 
in its reformulation of mathematical and scienti!c knowledge. Although the idea 
of synthetic a priori seems di#cult to disprove, we can ultimately see that it fails. 
Besides mathematics and laws of nature, Kant holds that formal logic is also a priori, 



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The Nature of Human Knowledge

that is, it has nothing to do with empirical data in its epistemic status and analysis.8  
Considering that logical rules, laws, or principles are totally abstract, and that they, in 
a way, manifest the structure of our minds, it, at !rst sight, seems again plausible to 
hold such a view that our knowledge or possess concepts, laws, principles, and so on 
that are a priori, necessary, and universal, then what we expect, when we look at the 
world, is that we never make a mistake in our conception of a priori, or that we never 
understand a priori things di$erently in relation to the physical world, since they are 
necessarily and universally true; and known or possessed before experience. However, 
as science and technology develop, nature continues to surprise us. A groundbreaking 
discovery has shown that our a priori and certain logical rules that we think of as 
necessary can tell us a di$erent story. It has been found, after the emergence of 
quantum logic, that one of the laws in formal logic, namely the distributive law, 
is not always true in quantum logic. “"e distributive law is sometimes false in 
quantum logic because of the superposition principle (and the projection postulate) 
in quantum mechanics.”9  "is situation has enormous implications as to the nature 
of human knowledge. While the aforementioned law works in the  macro-cosmos 
in which we live, it does not on the quantum scale. "e reason can obviously be 
propounded through the explanation that the universe works di$erently on di$erent 
scales, but the actual question that we must ask in our inquiry is: why do we call such 
laws (and other forms of a priori knowledge) a priori, and along with that, necessary, 
and universal? "e example of the distributive law, clearly, indicates that this is not 
the case. For, if these are a priori elements in our minds with such and such qualities, 
then how can we be mistaken even once? "ere should be a di$erent explanation 
as to the nature or origin of logic and, in the broadest scope, of human knowledge, 
as we see the implausibility of the presence of a priori knowledge. All these points 
suggest that empiricism provides the only solution to the question of the origin of 
human knowledge.

§3 The real leading roles in epistemology: 
syntheticity and a posteriority
Once we intend to eliminate the possibility of a priori knowledge, we are left with, 
as expected, only a posteriori knowledge. "us, it becomes natural to claim that 
knowledge, in fact, only stems from experience, and that it has nothing to do with 
any pre-given knowledge. Yet, it is still too early to arrive at this conclusion based on 
what we have covered so far, since there are other aspects in the defense of knowledge-
before-experience that we should examine. Notwithstanding the problematicality of a 
priori knowledge, some characteristics of human knowledge seem to show that there 
is a priority, but as we shall see, we can actually explain these through a posteriority. 

8 Immanuel Kant, Critique of Pure Reason, (B170).
9 Gibbins, P. F. “Why the Distributive Law Is Sometimes False.” (Analysis 44, no. 2, 1984), 64.



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In contemporary epistemology, one of the most controversial aspects is perhaps 
the presence of the analytic-synthetic dichotomy. "e consensus has been that the 
distinction between analytic and synthetic knowledge is as obvious and natural as 
that of a priori and a posteriori. "e latter distinction is totally understandable, 
because the origin of knowledge is either experience or mind, whereas in the former, 
learning becomes a matter of either observation or of appeal to language. "e problem 
concerning a priori appears within the context of its relation to analytic propositions: 
if there is no a priori, how can we then explain analytic truths? Let’s again consider 
the statement “All bachelors are unmarried men.” "ough it seems to be a matter of 
language, do we actually know before experience that this is the case? Do all these clear 
analytic descriptions or inferences not require the existence of a priority because of 
the fact that analyticity implies a priority or knowledge-before-experience? 

"e most well-known attack on the analytic-synthetic distinction, indubitably, 
comes from W.V.O. Quine. He attempts to show the nullity of this dichotomy 
through indicating that analyticity is circular. "at is, to learn the veracity of 
synthetic statements, we make observations or look at facts without appealing to 
the statements themselves, but for analytic propositions, we show this through 
analyticity itself, even though we believe that those propositions are true solely in 
virtue of their meanings. Along with Quine’s conclusion, it can be ascertained that 
analyticity, in fact, is fundamentally grounded upon syntheticity, and in this way, 
we come to the conclusion that the only way to have knowledge is foundationally 
syntheticity. "is paves the way for a posteriori knowledge by revealing facts in the 
world by means of experience, that is, empiricism is the only successful philosophy 
compared to rationalism or Kantian epistemology, which combines empiricism and 
rationalism. To comprehend how analyticity fails and is rooted in syntheticity, we 
should brie%y delineate Quine’s argumentation.

To begin his argument, he makes a distinction between analytic propositions with 
regards to their ways of justi!cation. He compartmentalizes analytic statements into 
two categories: the propositions that are logically true and the propositions that 
are true by synonymy. Consider this sentence: “No unmarried man is married.” In 
this classical example, we can logically see the truth of this sentence without any 
consideration of the interpretations of “man” and “married” when "no", "un-" 
and "is" have their ordinary meaning.10  On the other hand, we need to dissect 
analytic statements from the perspective of synonymy when we encounter this sort 
of example: “No bachelor is married.” Recalling that analytic propositions are true 
or not true only by virtue of meaning, the meanings of “bachelor” and “married” 
become important elements in this inquiry in a way that this sentence, by the 
synonymy between “bachelor” and “unmarried man,” can turn into “No unmarried 

10 W. V. Quine. “Main Trends in Recent Philosophy: Two Dogmas of Empiricism.” ("e Philosophical Review 60, no. 
1, 1951), 23.



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The Nature of Human Knowledge

man is married.” Analyticity by synonymy is ultimately understood via analyticity by 
logic, but this transition, Quine points out, is problematic in that it is circular, and 
this will later show us how possible it is to surmount the di#culty of understanding 
analyticity on the grounds of syntheticity without falling into circularity.

A !rst strategy could be to use the de!nitions of “bachelor” and “unmarried man” in 
order to demonstrate how they are synonymous. Surely, a dictionary can help us !nd 
out their de!nitions, but because a dictionary only provides a report of the de!nition 
of a word which is already known, this method does not represent the synonymy 
between them. If so, what is the way then to know that they are synonymous and 
hence, constitute an analytic statement that is true only in virtue of meaning without 
requiring any empirical data? At this point, Quine tries to use interchangeability in 
their synonymy.11  According to this conception, if two terms are interchangeable 
in all contexts without any change in their truth-value, they are synonymous. For 
example, “‘Bachelor’ has fewer than ten letters.” "is statement gives a quality 
of “bachelor,” but it also indicates that "bachelor" and "unmarried man" are not 
interchangeable in this sentence, since obviously, we cannot say “‘unmarried man’ 
has fewer than ten letters.” "erefore, we have no reason to justify the analytic 
sentence “A bachelor is an unmarried man” under these circumstances. However, 
when we attempt to appeal to interchangeability for synonymy, that which we are 
really concerned with is not the formal structure of the words, but rather, Quine 
argues, cognitive synonymy, how we actually understand them. Yet, at this point, 
another issue arises. "e problem is that we have to presuppose the knowledge of 
the meaning of analyticity to expound cognitive synonymy. To put it another way, it 
is simply asserted that we know the synonymy between “bachelor” and “unmarried 
man” by claiming that they are synonymous, or by referring again to their meanings: 
using analyticity. In contrast, Quine states, “What we need is an account of cognitive 
synonymy not presupposing analyticity.”12  We can, hence, say that putting forward 
cognitive synonymy or proposing that we know the synonymy between the words 
simply in virtue of our cognitive ability to know their meanings without any further 
justi!cation is another way to use analyticity.

As another attempt to resolve this problem, Quine suggests the use of “necessarily” 
in order to circumvent this situation.  He argues that if we use such an adverb, 
it becomes possible to avoid using meanings, and thus, analyticity. Nonetheless, 
the same problem comes to the surface for the reason that the concept of necessity 
applies only to analytic propositions; justifying a sentence through including 
“necessarily” still presupposes analyticity. Consider the statement “Necessarily all and 
only bachelors are bachelors”. Since we hold that “bachelor” and “unmarried man” 
are interchangeable, this proposition turns into “Necessarily all and only bachelors 

11 Ibid, Pg. 27.
12 Ibid, Pg. 28.



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Dianoia: The Undergraduate Philosophy Journal of Boston College

are unmarried men.” We try to explain this interchangeability through an appeal to 
necessity as an alternative to the use of meaning and avoid analyticity, but indeed, 
what is done here is to change the site of analyticity from the synonymy between the 
words “bachelor” and “unmarried man” to “necessarily.” Analyticity, in this situation, 
is used by means of necessity, because “[t]o suppose that [necessity makes sense] is to 
suppose that we have already made satisfactory sense of 'analytic.'”13  "erefore, only 
the acceptance of analyticity can establish synonymy, and in fact, propositions like 
this, theoretically, show no di$erence from statements that are logically true in terms 
of their justi!cations.

Quine argues for the circularity of analyticity to explicate the impossibility of 
analyticity. We can conclude, therefore, that the fundamental logic behind analyticity 
is that analytic statements are true, because they are true. However, there is still a 
question: if there is no analyticity, how do we still know “All bachelors are unmarried 
men” or “All squares have four equal sides” before experience? Perhaps, the real 
question should be: do we really know them before experience? "is question is 
di#cult to answer if they are a priori self-evident knowledge that require no further 
justi!cation to be held. In other words, what if they are self-evidently true in virtue 
of necessary and universal a priori knowledge as manifestations of our a priori 
logical reasoning that has nothing to do with our presuppositions or the way we use 
language? 

Language is a way to express our thoughts or beliefs in accordance with some logical 
structures in our minds, and especially in analytic propositions, it is crucial that true 
statements are the ones that comply with our logic. "at is the reason that Quine states 
that when we use analyticity, we indeed turn statements that are true by synonymy 
into statements that are logically true. "us, along with his argument that analyticity 
is circular, the major takeaway from his argument is that analyticity depends on the 
idea of a priori logic. "is allows us to claim that “All bachelors are unmarried men” 
is true because it is logically true and requires no further justi!cation. However, when 
it comes to the original way we know them, the dispute between rationalism and 
empiricism arises: is it something we know before experience, or are there really such 
a priori concepts or categories that shape our judgments, etc.? In this case, what is in 
question is the origin of logic since, as we have shown, analyticity is fundamentally 
grounded upon logic. 

Yet, in our discussion of the distributive law, we saw that the idea of a priori logic 
could be wrong. So, does this totally eliminate the presence of a priori logic in the 
context of analyticity? After all, we can roughly express that the purest form of 
analyticity is “X is X” or “X=X” "erefore, the question turns into “How is ‘X is X’ 
or ‘X=X’ true?” and in fact, other than how synonymy occurs, this is the fundamental 

13 Ibid, Pg. 29



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goal of analyticity.. Is “X is X” or “X=X” known before experience? "e answer is that 
it is indeed known after experience even though this appears counter-intuitive. In 
order to create a proper conception of X in our minds and argue that it is identical 
with itself or the same as something else, we need to experience X in relation to 
other things. Similarly, to understand “A bachelor is a bachelor” or “An unmarried 
man is an unmarried man,” we !rst need to understand the meanings of bachelor 
and unmarried man. Consider the !rst example. If this statement were an analytic 
proposition in a way that it is argued, then we would only comprehend this sentence 
by reading it. Yet, what guarantees that the former bachelor and the latter bachelor 
are the same? "e former could mean an unmarried man, whereas the latter could 
mean a person who holds a !rst degree from a university. So as to establish the sense 
of analyticity in the form of “X is X,” we need to ensure that they have the same 
meaning, but we can only do that empirically. 

"us, we leave the realm of analyticity and enter syntheticity, and this brings 
about the emergence of a posteriori knowledge. "is situation may not happen 
for “An unmarried man is an unmarried man,” since the meaning of “unmarried 
man” is understood more precisely unlike “bachelor.” Considering, however, that 
the meanings of words in a language depends on the context or language in which 
they are being used, this could apply to any word, and that shows the empirical 
aspect of language and the necessity to appeal to the external world to verify its true 
meaning. Hence, it is not surprising to see that we can understand “All bachelors 
are bachelors” after experiencing and creating a suitable conceptualization of what 
is being experienced. We can claim, therefore, that analyticity lies on the ground of 
syntheticity, and that the knowledge acquired from so-called analytic statements like 
“All bachelors are unmarried men” or “X is X” is indeed synthetic a posteriori because 
we need to check the veracity of these statements, according to the way they are being 
used, through observation, and this syntheticity gives rise to a posteriori knowledge 
rather than necessary and universal a priori knowledge.

"e same process occurs on the grounds of not only language, but also our 
conceptualizations in the sense of understanding the existence of ourselves and the 
world. For example, when we state, “All squares have four equal sides,” we describe an 
abstraction based on experience in the sense that after seeing squares with the same 
property —four equal sides—we conceptualize this shape and claim to know, in an 
analytic a priori manner, that “All squares have four equal sides.” "is demonstrates 
how we come to know the world through generalizations. As we have seen, 
empirical generalizations, according to Hume, are synthetic a posteriori and cannot 
be considered to be necessary or universal.  "erefore we cannot reach any certain 
knowledge of the world like laws of nature, and unlike his idea of “relations of ideas”, 
or in modern version analytic a priori it can be said that these sorts of propositions, 
laws of nature or logical principles, can be known in a synthetic a posteriori way by 



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rejecting analyticity and a priori through unfalsi!able scienti!c generalizations of our 
experience of reality.

For instance, we have discussed the distributive law and suggested that since it does 
not work under the conditions of quantum mechanics, it cannot have a necessary 
and universal property, and hence, we cannot regard it as a priori. Instead, as we do 
for every phenomenon, we can think of this law as synthetic a posteriori knowledge, 
but this does not mean that it cannot be generalized and count as certain or universal. 
Before quantum logic emerged, this law had worked perfectly, and nobody questioned 
the truth of it. However, once quantum physics changed this, its truth, necessity, or 
universality started to be questioned. Does this suggest that we should abandon this 
law while speaking of human knowledge? "e answer, of course, should be no. Just 
because the law does not always work on the quantum scale does not mean that it 
is wrong in every situation. Likewise, Newton came up with several laws in order to 
describe how the universe works, but it was said that Newtonian physics is wrong 
after Einstein. Yet, it is still used in science and technology. If it is wrong, why is it 
used? "e reason is obviously that it does work particularly in machine parts, %uids, 
planets, spacecrafts, and so on, but it does not within the context of Einsteinian 
physics or quantum mechanics. Furthermore, we still call Newtonian laws laws. If 
these are wrong, how can they be called laws?

To conceive what is really happening here, we should understand how laws, principles, 
axioms, logical rules, etc. come into existence on the grounds of unfalsi!able scienti!c 
generalizations. When we say, for example, that the sum of the interior angles of a 
triangle is 180 degrees, through the scienti!c method, it is ultimately concluded that 
this is true and represents a law, rule, or principle. A law then is something that is 
unfalsi!able. "is is indeed how we know facts about the world and our logic. 

Similarly, logic is an extension of the external world in the sense that after making 
observations and generalizing facts, we conceptualize what we see in the world and 
state some certain rules or principles. However, as science and technology develop, we 
gain a broader understanding of how the universe works and start questioning what 
we think of as certain. We found out that the laws of Newtonian physics or some 
logical laws like the distributive law do not work in all cases. Yet, these still work well 
in the conditions that we most often encounter. After Einstein and quantum physics, 
it was understood that Newtonian physics is wrong, but it still describes the world 
that we experience by common-sense with high precision. "is shows that those are 
unfalsi!able in this world, because their veracities were tested in this world, and along 
with that, they have become laws in this world. Yet, when we discover other areas of 
the universe, new laws, rules, or principles concerning the di$erent mechanisms of 
these areas emerge. 



65Issue IX ɢ Spring 2022

The Nature of Human Knowledge

"us, we can eventually see that our whole knowledge of the world and logic can be 
expressed via syntheticity and a posteriority, since all these facts require experience to 
be known and lack necessity and universality in the broadest scope. "e distributive 
law, for example, can count as a law when it is observed only in the world where 
it is unfalsi!able, but in quantum mechanics, it cannot. It is synthetic, because we 
need to look at the world or the speci!c conditions where it is being used in order to 
see if it is true, and it is a posteriori, since we come to know it only after experience 
through unfalsi!able generalizations under certain conditions. "is endorses the 
idea that human knowledge stems only from our empirical observations, not from 
a priori phenomena. "is argument, therefore, strongly supports the repudiation 
of knowledge-before-experience, and thus rationalism. Notwithstanding all those 
points, there are two aspects of the issue to be explained such as the knowledge of 
the things about which unfalsi!ability is not always used and as a more fundamental 
subject, the knowledge of the self.

§4 The Knowledge of the Self and the External 
World
When we see a chair, for instance, we think we know that there is a chair. We do not 
think there is a need to rely upon the cumulative knowledge of humanity to make 
sure that our knowledge about the presence of the chair is unfalsi!able. Moreover, 
what guarantees that this holistic and shared knowledge of humanity is true? How 
can we be sure that what we are seeing is true? What if there is no chair, and we 
live in a delusion? Surely, this can only bring us to Cartesian skepticism. If only 
empiricism can explain the nature of human knowledge, and if the world where we 
live might be a delusion, then how can we really experience and know the world 
or trust empiricism at all? At this point, the only knowledge we can have, it could 
be argued, is our individual existence. We can only say, “I think, therefore, I am.” 
However, is this not known independently of experience? What we have seen so far 
champions the view that knowledge independent of experience is impossible, but 
can we argue that the knowledge of the self is the only a priori knowledge, and thus, 
empiricism ultimately fails? 

Descartes makes a strong case when he argues, “I think, therefore, I am.” It is, most 
of the time, held that he proves his existence independently of the external world by 
doubting everything. At the most fundamental level, he, in fact, knows nothing, but 
his a priori existence. He knows it, because it is self-evident to him, and this situation 
requires no further justi!cation. "is is a crucial point in any inquiry of human 
knowledge, since after considering skeptical arguments (particularly, the Agrippan 
problem) that cast a shadow over the possibility of human knowledge and argue that 
epistemic justi!cation is impossible, we can more easily establish the importance of 
having self-evident truths upon which the rest of human knowledge. "at is to say, 
we need self-evident knowledge, at least at the fundamental level, to speak of the 



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Dianoia: The Undergraduate Philosophy Journal of Boston College

possession of knowledge. If so, what is this basic and self-evident knowledge, and is 
it a priori? 

At this point, seemingly, we agree with Descartes with regards to the existence of 
self-evident knowledge, but when it comes to its origin or how it is found,there is 
an apparent di$erence. We will focus on the idea of the self-evident existence of 
the self which, in this argumentation, is independent of the external world, and 
this independence, indeed, is the element that causes a problem here. In order to 
conceive this issue, we should !rst comprehend how we come to know ourselves. "e 
process of knowing the self only occurs in relation to things that we perceive in the 
external world. In other words, this knowledge becomes a process of self-perception 
only after the perceiver perceives himself or herself, and becomes aware of his or her 
existence. However, once we try to isolate ourselves by focusing on our own distinct 
self as though it is totally independent of the external world in a way that Descartes 
does, we !nd ourselves in a delusion in respect of the origin of the self by thinking 
that it can be known even in the absence of experience. Descartes argues that we 
can know that we exist without experiencing anything, but the knowledge of the 
self only arises after experience, since self-realization occurs after understanding that 
we are the perceiver. Even if we think that the only thing we know is our a priori 
existence, the properties or nature of this existence will be limited to what we have 
experienced so far. It can be proposed, therefore, that the knowledge of the self is not 
analytic or a priori, but rather, more precisely, synthetic a posteriori in that it requires 
experience every time by realizing the distinction between the perceiver and what is 
being perceived, and it cannot be known before experience.

After all, although the knowledge of the self arises as a result of experience, we can 
still argue that it is self-evident, since regardless of its origin this knowledge ultimately 
appears to our consciousness in a way that it is known directly or self-evidently. 
When it comes to the knowledge of objects in the external world we can say that 
their existence is also self-evident because of the fact that, regarding our relationship 
with the external world in terms of the emergence of our self-awareness, it can be 
inferred that their existence is a main requisite to realize our own existence that 
emerges as a part of the physical reality, and thus, similar to how we self-evidently 
know the self, their existence appears to us as self-evident. Moreover, this direct 
shift in our comprehension of existence allows us to look at reality in a much more 
comprehensive manner in the sense that we can no longer grasp reality from the 
internal perspective in which we can only know our own existence, but only from 
the external perspective in which we can look at ourselves as a part of the external 
world. However, we know that we are living beings that consist of physiological 
systems that could have malfunctions or that could cause illusions, etc. "at is to say, 
we could sometimes be wrong in our judgments, but under normal circumstances 
of our biology, when our body works without any problem, we will not be mistaken 



67Issue IX ɢ Spring 2022

The Nature of Human Knowledge

very often. When one is drunk, one could argue that there are two chairs in the 
room actually when there is one, or there could be an illusion for a sober person, but 
if more people independent of each other test this claim several times, then it will 
eventually be con!rmed that there is one chair in the room.  "is perfectly describes 
the scienti!c method with the notion of unfalsi!ability. "is is how certain facts, 
laws, or principles are established within the synthetic a posteriori framework. Yet, 
as we have said, this is valid for the world we examine. When electrons and protons 
are considered, on this scale, there will be no chair, only particles. Does it, however, 
mean that what we see, in fact, is a delusion? After considering that the existence 
of the chair in the room is self-evident to us, we can conclude that the world we 
experience is not a delusion, but it represents reality to which we have a direct access, 
and that at the same time, it is not the ultimate reality. We cannot know the ultimate 
reality due to the fact that our experience and knowledge are limited. "is situation 
does not necessarily mean that we are wrong as to our judgments of reality, but 
instead, as we develop new instruments that broaden our horizon by making more 
empirical data visible to us, expanding our knowledge about reality in various aspects 
becomes possible.


