Within philosophical discourse, rationalism constitutes an epistemological perspective asserting that reason serves as the primary origin and arbiter of knowledge, or that reason inherently supersedes alternative methods of knowledge acquisition. This stance frequently contrasts with other potential sources, including faith, tradition, or empirical sensory experience. More precisely, rationalism is conceptualized as a methodological framework or theoretical construct where the ultimate criterion for truth is intellectual and deductive, rather than sensory.
During the Enlightenment, a significant philosophical contention arose between rationalism, occasionally conflated with innatism, and empiricism. Proponents of rationalism, such as René Descartes, posited that knowledge is predominantly innate, enabling the intellect—an intrinsic faculty of the human mind—to directly apprehend or deduce logical truths. Conversely, empiricists, exemplified by John Locke, contended that knowledge is not primarily innate but is optimally acquired through meticulous observation of the external physical world via sensory experiences. Rationalists maintained that fundamental principles in logic, mathematics, ethics, and metaphysics possess an inherent truth so profound that their denial inevitably leads to contradiction. Their profound confidence in reason led them to deem empirical proof and physical evidence superfluous for establishing certain truths, asserting that "there are significant ways in which our concepts and knowledge are gained independently of sense experience".
The varying degrees of emphasis placed on this methodology or theory result in a spectrum of rationalist perspectives, ranging from the moderate assertion "that reason has precedence over other ways of acquiring knowledge" to the more radical claim that reason constitutes "the unique path to knowledge". Within a pre-modern conceptualization of reason, rationalism aligns with philosophy itself, the Socratic pursuit of inquiry, or the zetetic (skeptical) approach to interpreting authority, which seeks the underlying or essential causes of phenomena as they present themselves to our perception of certainty.
Background
Rationalism possesses a philosophical lineage extending back to antiquity. The analytical character inherent in much philosophical investigation, coupled with the recognition of seemingly a priori knowledge domains like mathematics, and the insistence on acquiring knowledge through rational faculties (often dismissing, for instance, direct revelation), have rendered rationalist themes exceptionally prominent throughout the history of philosophy.
Subsequent to the Enlightenment, rationalism is typically linked to the integration of mathematical methodologies into philosophy, as evidenced in the writings of Descartes, Leibniz, and Spinoza. This particular manifestation is frequently termed continental rationalism, owing to its prevalence in European continental philosophical traditions, in contrast to Britain where empiricism held sway.
Nevertheless, the demarcation between rationalists and empiricists was a later conceptualization, likely unrecognized by the philosophers themselves at the time. Furthermore, the distinction between these two philosophical schools is not as absolute as frequently portrayed; for instance, Descartes and Locke shared comparable perspectives regarding the essence of human ideas.
Adherents of certain rationalist variations contend that, by commencing with foundational principles akin to geometric axioms, one could deductively ascertain all other conceivable knowledge. Baruch Spinoza and Gottfried Leibniz stand out as prominent philosophers who articulated this perspective most distinctly; their endeavors to address the epistemological and metaphysical challenges posed by Descartes significantly advanced the core tenets of rationalism. Both Spinoza and Leibniz maintained that, in principle, all forms of knowledge, including scientific understanding, could be acquired solely through the application of reason. However, they both acknowledged that this was not feasible in practice for human beings, except within specialized domains such as mathematics. Nevertheless, Leibniz conceded in his work Monadology that "we are all mere Empirics in three fourths of our actions."
Political usage
Since the Enlightenment, political rationalism has historically championed a "politics of reason," prioritizing rationality, deontology, utilitarianism, secularism, and irreligion. While initially characterized by antitheism, this latter element evolved to embrace pluralistic reasoning, applicable across diverse religious and irreligious ideologies. Philosopher John Cottingham observed this social conflation, where rationalism, as a methodology, became erroneously equated with atheism, a distinct worldview:
Historically, particularly during the 17th and 18th centuries, the term 'rationalist' frequently denoted freethinkers holding anti-clerical and anti-religious viewpoints. For a period, this word acquired a distinctly pejorative force; for instance, in 1670, Sanderson disparagingly referred to 'a mere rationalist, that is to say in plain English an atheist of the late edition...'. Currently, the use of 'rationalist' to characterize a worldview that excludes the supernatural is diminishing, largely replaced by terms such as 'humanist' or 'materialist'. Nevertheless, this older usage continues to endure.
Philosophical Usage
Rationalism is frequently juxtaposed with empiricism. Broadly interpreted, these perspectives are not inherently mutually exclusive, as certain definitions permit a philosopher to embrace both rationalist and empiricist tenets. At its most extreme, the empiricist stance posits that all ideas are acquired a posteriori, meaning through experience, whether via external senses or internal sensations like pain and gratification. Fundamentally, empiricists contend that knowledge originates from or is directly dependent on experience. Conversely, rationalists assert that knowledge is attained a priori, through logical reasoning, thereby independent of sensory input. As Galen Strawson succinctly articulated, "you can see that it is true just lying on your couch. You don't have to get up off your couch and go outside and examine the way things are in the physical world. You don't have to do any science."
The central divergence between these two philosophies concerns the foundational origin of human knowledge and the appropriate methodologies for validating perceived understanding. While both fall within the domain of epistemology, their contention primarily revolves around the concept of "warrant," which itself is subsumed under the broader epistemic framework of justification theory. This theory, a component of epistemology, seeks to elucidate the justification of propositions and beliefs. Epistemologists investigate various epistemic attributes of belief, encompassing justification, warrant, rationality, and probability. Among these four terms, "warrant" has garnered the most extensive usage and discussion by the early 21st century. Broadly defined, justification represents the rationale underlying an individual's (probable) adherence to a belief.
When A asserts a claim and B subsequently challenges it, A's typical response involves furnishing justification for that assertion. The specific methodology employed to provide such justification delineates the distinctions between rationalism and empiricism, among other philosophical perspectives. A significant portion of the discourse within these domains centers on scrutinizing the essence of knowledge and its interrelationship with associated concepts like truth, belief, and justification.
Fundamentally, rationalism is predicated on three core assertions. To be considered a rationalist, an individual must subscribe to at least one of these: the intuition/deduction thesis, the innate knowledge thesis, or the innate concept thesis. Furthermore, a rationalist may also embrace the Indispensability of Reason claim or the Superiority of Reason claim, though adherence to either of these is not a prerequisite for identifying as a rationalist.
The indispensability of reason thesis posits: "The knowledge we gain in subject area, S, through intuition and deduction, alongside the innate ideas and knowledge instances within S, could not have been acquired via sensory experience." Essentially, this thesis asserts that empirical experience is insufficient to yield the knowledge derived from reason.
The superiority of reason thesis states: "The knowledge we acquire in subject area S through intuition and deduction, or that which is innately present, surpasses any knowledge obtained via sensory experience." This thesis, therefore, contends that reason constitutes a superior source of knowledge compared to empirical experience.
Rationalists frequently adopt analogous positions on other philosophical aspects. Most rationalists reject skepticism concerning areas of knowledge they assert are knowable a priori. The assertion that certain truths are innately known necessitates the rejection of skepticism regarding those truths. Especially for rationalists who embrace the Intuition/Deduction thesis, the concept of epistemic foundationalism frequently emerges. This perspective posits that certain truths are known independently, without reliance on other beliefs, and subsequently serve as a foundation for acquiring further knowledge.
Intuition/Deduction Thesis
"Some propositions in a particular subject area, S, are knowable by us by intuition alone; still others are knowable by being deduced from intuited propositions."
Broadly defined, intuition constitutes a priori knowledge or an immediate experiential belief characterized by its directness, representing a form of rational insight. It involves a direct apprehension that confers a warranted belief. The precise nature of intuition, however, remains a subject of considerable debate. Similarly, deduction is typically defined as the process of reasoning from one or more general premises to attain a logically certain conclusion. Through the application of valid arguments, conclusions can be deduced from intuited premises.
For instance, by integrating both concepts, one can intuit that the number three is prime and exceeds two. From this intuited knowledge, one can then deduce the existence of a prime number exceeding two. Consequently, the combination of intuition and deduction yields a priori knowledge, acquired independently of sensory experience.
In support of this thesis, Gottfried Wilhelm Leibniz, a prominent German philosopher, asserts:
The senses, although they are necessary for all our actual knowledge, are not sufficient to give us the whole of it, since the senses never give anything but instances, that is to say particular or individual truths. Now all the instances which confirm a general truth, however numerous they may be, are not sufficient to establish the universal necessity of this same truth, for it does not follow that what happened before will happen in the same way again. … From which it appears that necessary truths, such as we find in pure mathematics, and particularly in arithmetic and geometry, must have principles whose proof does not depend on instances, nor consequently on the testimony of the senses, although without the senses it would never have occurred to us to think of them…
Empiricists, such as David Hume, have acknowledged this thesis as a framework for describing the relationships between our concepts. Within this framework, empiricists contend that truths can be intuited and deduced from knowledge acquired a posteriori.
Varying the subject matter to which the Intuition/Deduction thesis is applied generates diverse arguments. A majority of rationalists concur that mathematics is knowable through the application of intuition and deduction. Some extend this to encompass ethical truths within the scope of knowledge attainable via intuition and deduction. Additionally, certain rationalists assert that metaphysics is also knowable through this thesis. Evidently, as rationalists expand the range of subjects claimed to be knowable by the Intuition/Deduction thesis, their certainty in warranted beliefs increases, and their adherence to the infallibility of intuition becomes stricter, leading to more controversial claims and a more radical form of rationalism.
Beyond the variation in subject matter, rationalists also modulate the strength of their assertions by refining their conception of epistemic warrant. While some rationalists define warranted beliefs as those entirely devoid of doubt, others adopt a more conservative stance, considering warrant to be belief beyond a reasonable doubt.
Rationalists also exhibit divergent interpretations and assertions regarding the relationship between intuition and truth. Certain rationalists posit the infallibility of intuition, asserting that whatever is intuited as true is inherently so. Conversely, more contemporary rationalists acknowledge that intuition may not invariably provide certain knowledge, thereby accommodating the possibility of a deceiver inducing a false proposition, analogous to how an external agent might cause perceptions of nonexistent objects.
Innate Knowledge Thesis
"We have knowledge of some truths in a particular subject area, S, as part of our rational nature."
The Innate Knowledge thesis shares a fundamental similarity with the Intuition/Deduction thesis, as both posit that knowledge is acquired a priori. However, their explanations diverge regarding the mechanism of knowledge acquisition. The Innate Knowledge thesis, as its designation implies, asserts that knowledge inherently constitutes a component of our rational nature. While empirical experiences can initiate a process that brings this knowledge into conscious awareness, these experiences do not themselves impart the knowledge. Instead, the knowledge is considered to have been present from inception, with experience merely serving to clarify it, much like a photographer adjusts a lens aperture to sharpen a picture's background, which was always present but previously unfocused.
This thesis addresses a fundamental epistemological challenge concerning the nature of inquiry, initially articulated by Plato in his dialogue Meno. Plato's inquiry explores how individuals acquire knowledge of a geometric theorem through investigation. He posits a paradox: "If we already possess the knowledge, there is no need for inquiry. If we lack the knowledge, we cannot identify what we are searching for, nor recognize it upon discovery. Consequently, knowledge of a theorem cannot be gained through inquiry, yet we demonstrably possess such knowledge." The Innate Knowledge thesis provides a resolution to this paradox. By asserting that knowledge resides within us, whether consciously or unconsciously, rationalists contend that learning, in its conventional sense, is not an acquisition of new information but rather an activation or recognition of pre-existing understanding.
The Innate Concept Thesis
"We have some of the concepts we employ in a particular subject area, S, as part of our rational nature."
Analogous to the Innate Knowledge thesis, the Innate Concept thesis proposes that certain concepts are intrinsic to our rational faculties. These concepts are inherently a priori, rendering sensory experience inconsequential for discerning their fundamental character, although such experience may facilitate their emergence into conscious awareness.
In his seminal work, Meditations on First Philosophy, René Descartes delineates three categories of ideas, stating: "Among my ideas, some appear to be innate, some to be adventitious, and others to have been invented by me. My understanding of what a thing is, what truth is, and what thought is, seems to derive simply from my own nature. But my hearing a noise, as I do now, or seeing the sun, or feeling the fire, comes from things which are located outside me, or so I have hitherto judged. Lastly, sirens, hippogriffs and the like are my own invention."
Adventitious ideas represent concepts acquired through sensory experiences, exemplified by sensations like heat, as they originate from external sources, conveying their own distinct qualities and being beyond volitional control. Ideas invented by individuals, such as those prevalent in mythology, legends, and fairy tales, are constructs derived from other pre-existing concepts. Finally, innate ideas, including notions of perfection, are those concepts that arise from mental processes transcending what direct or indirect experience can furnish.
Gottfried Wilhelm Leibniz championed the concept of innate ideas, positing that the mind actively shapes the nature of concepts. To illustrate this, he famously compared the mind to a block of marble in his work New Essays on Human Understanding.
This analogy employs a block of veined marble, contrasting it with a uniform block or a blank slate, philosophically termed tabula rasa. If the soul were a blank slate, truths would reside within us akin to the figure of Hercules in an undifferentiated marble block, where the marble is entirely neutral regarding the form it receives. However, if the stone contained veins prefiguring Hercules, it would possess an inherent predisposition, making Hercules, in a sense, innate. Uncovering these veins would necessitate effort—polishing and removing obstructing material. Similarly, ideas and truths are innate within us as natural inclinations, dispositions, habits, or potentialities, rather than as fully realized activities. These potentialities, though often imperceptible, are consistently accompanied by corresponding activities.
Philosophers like John Locke, a prominent Enlightenment empiricist, contend that the Innate Knowledge thesis and the Innate Concept thesis are identical. Conversely, figures such as Peter Carruthers assert their distinctness. Within rationalism, the degree of controversy and radicalism associated with a philosopher's stance directly correlates with the quantity and variety of concepts posited as innate. The text highlights that "the more a concept seems removed from experience and the mental operations we can perform on experience the more plausibly it may be claimed to be innate." For instance, the concept of a perfect triangle, which lacks direct experiential counterparts, is considered a more compelling candidate for innateness than the concept of pain, which is directly experienced.
Historical Overview
Rationalist Philosophy in Western Antiquity
While modern rationalism emerged subsequent to antiquity, ancient philosophers established its foundational principles. Notably, they introduced the understanding that certain knowledge is accessible exclusively through rational thought.
Pythagoras (570–495 BCE)
Pythagoras stands as one of the earliest Western philosophers to emphasize rational insight. Revered as a distinguished mathematician, mystic, and scientist, he is primarily recognized for the eponymous Pythagorean theorem and for elucidating the mathematical correlation between lute string lengths and musical pitches. Pythagoras "believed these harmonies reflected the ultimate nature of reality," encapsulating his implicit metaphysical rationalism with the dictum 'All is number.' It is posited that he anticipated the rationalist perspective, later echoed by Galileo (1564–1642), envisioning a universe entirely governed by mathematically expressible laws. Furthermore, he is reputedly the first individual to identify himself as a philosopher, meaning a 'lover of wisdom.'
Plato (427–347 BCE)
Plato accorded immense significance to rational insight, a principle evident in his seminal works, including Meno and The Republic. He expounded the Theory of Forms (also known as the Theory of Ideas), which postulates that the ultimate and most fundamental reality transcends the mutable material world perceived through sensation. Instead, it resides in an abstract, non-material yet substantial realm of forms or ideas. According to Plato, these forms were exclusively accessible through reason, not sensory experience. His profound reverence for reason, particularly within geometry, is underscored by the apocryphal inscription above his academy's entrance: "Let no one ignorant of geometry enter."
Aristotle (384–322 BCE)
Aristotle's primary contribution to rationalist thought was the development and application of syllogistic logic in argumentation. He defined a syllogism as "a discourse in which certain (specific) things having been supposed, something different from the things supposed results of necessity because these things are so." Notwithstanding this broad definition, Aristotle confined his analysis to categorical syllogisms, comprising three categorical propositions, within his treatise Prior Analytics. His work also encompassed categorical modal syllogisms.
The Middle Ages
While the three prominent Greek philosophers held divergent views on specific doctrines, they uniformly affirmed that rational thought could unveil self-evident knowledge, which humans could not otherwise ascertain without the application of reason. Following Aristotle's demise, Western rationalistic thought predominantly manifested through its integration with theology, exemplified in the writings of Augustine, the Islamic philosophers Avicenna (Ibn Sina) and Averroes (Ibn Rushd), and the Jewish philosopher and theologian Maimonides. The Waldensian sect similarly incorporated rationalism into its tenets. A significant development in the Western intellectual tradition was Thomas Aquinas's thirteenth-century endeavor to synthesize Greek rationalism with Christian revelation. Generally, the Roman Catholic Church perceived Rationalists as a threat, characterizing them as individuals who, "while admitting revelation, reject from the word of God whatever, in their private judgment, is inconsistent with human reason."
Classical Rationalism
René Descartes (1596–1650)
Descartes is recognized as the progenitor of modern rationalism and is widely acclaimed as the 'Father of Modern Philosophy.' A substantial portion of subsequent Western philosophical discourse constitutes a response to his influential works, which continue to be rigorously studied today.
Descartes posited that only knowledge of eternal truths—encompassing mathematical principles and the epistemological and metaphysical underpinnings of the sciences—could be acquired solely through reason; other forms of knowledge, such as physics, necessitated empirical engagement with the world, facilitated by the scientific method. He further contended that despite dreams appearing as vivid as sensory experiences, they cannot furnish individuals with genuine knowledge. Moreover, given that conscious sensory experience can engender illusions, sense perception itself is inherently susceptible to doubt. Consequently, Descartes deduced that a rational pursuit of truth mandates skepticism toward all beliefs derived from sensory reality. He expounded upon these convictions in seminal works such as Discourse on the Method, Meditations on First Philosophy, and Principles of Philosophy. Descartes devised a methodology for attaining truths, asserting that any concept not discernible by the intellect (or reason) cannot be classified as knowledge. According to Descartes, these truths are apprehended "without any sensory experience." Truths accessed through reason are disaggregated into fundamental elements comprehensible by intuition, which, through a purely deductive process, yield clear insights into reality.
As a direct outcome of his method, Descartes thus asserted that reason alone determines knowledge, operating independently of the senses. For instance, his celebrated dictum, cogito ergo sum, or "I think, therefore I am," represents an a priori conclusion, meaning it is reached prior to any empirical experience concerning the matter. The fundamental implication is that the very act of doubting one's existence inherently proves the existence of an "I" performing the thought. In essence, doubting one's own doubt is illogical. For Descartes, this served as an irrefutable foundational principle for all other forms of knowledge. Descartes also advanced a metaphysical dualism, differentiating between the substances of the human body ("res extensa") and the mind or soul ("res cogitans"). This critical distinction remained unresolved, giving rise to what is known as the mind–body problem, given that these two substances within the Cartesian system are posited as independent and irreducible.
Baruch Spinoza (1632–1677)
Baruch Spinoza's philosophy, developed in seventeenth-century Europe, constitutes a systematic, logical, and rational framework. This philosophical system, built upon foundational principles, exhibits internal consistency and sought to address fundamental existential questions, notably positing that "God exists only philosophically." Spinoza drew significant influence from figures like Descartes, Euclid, and Thomas Hobbes, alongside theologians within the Jewish philosophical tradition, including Maimonides. Nevertheless, his work diverged considerably from the prevailing Judeo-Christian-Islamic intellectual traditions. Numerous Spinozan concepts persist in challenging contemporary thinkers, and many of his principles, especially those concerning emotions, bear relevance for modern psychological methodologies. Even prominent intellectuals, such as Goethe, have historically found Spinoza's "geometrical method" challenging to grasp. His magnum opus, Ethics, is characterized by unresolved ambiguities and a formidable mathematical structure, emulating Euclidean geometry. Spinoza's philosophical contributions garnered considerable intellectual interest and attracted adherents like Albert Einstein.
Gottfried Leibniz (1646–1716)
Gottfried Leibniz, a pivotal figure in seventeenth-century rationalism, made substantial contributions across diverse disciplines including metaphysics, epistemology, logic, mathematics, physics, jurisprudence, and the philosophy of religion, earning him recognition as one of the last "universal geniuses." His philosophical system, however, did not evolve in isolation from these broader intellectual advancements. Leibniz explicitly repudiated Cartesian dualism and asserted the non-existence of a material world. According to Leibniz, reality comprises an infinite multitude of simple substances, which he termed "monads," a concept directly influenced by Proclus.
Leibniz formulated his monad theory as a direct response to the philosophies of both Descartes and Spinoza, as his disagreement with their perspectives necessitated the development of an alternative framework. In Leibniz's metaphysics, monads represent the fundamental constituents of reality, forming both inanimate and animate entities. While these fundamental units reflect the entire universe, they remain exempt from the principles of causality and spatial relations, which he characterized as "well-founded phenomena." Consequently, Leibniz proposed his doctrine of pre-established harmony to explain the observed causality within the phenomenal world.
Immanuel Kant (1724–1804)
Immanuel Kant stands as a foundational figure in modern philosophy, establishing the conceptual parameters that have engaged all subsequent philosophical inquiry. Kant posited that human perception actively shapes natural laws and that reason serves as the ultimate origin of morality. His philosophical contributions maintain significant influence in contemporary discourse, particularly across disciplines such as metaphysics, epistemology, ethics, political philosophy, and aesthetics.
Kant designated his epistemological framework "Transcendental Idealism," initially articulating these perspectives in his seminal work, The Critique of Pure Reason. Within this text, he contended that both rationalist and empiricist doctrines suffered from inherent limitations. Addressing rationalists, he broadly asserted that pure reason becomes fallacious when it transgresses its boundaries, purporting to comprehend entities inherently transcending all possible experience, such as the existence of God, free will, and the immortality of the human soul. Kant termed these entities "The Thing in Itself," further arguing that their inherent nature as objects beyond all possible experience precludes human knowledge of them. Conversely, he posited to empiricists that while empirical experience is indeed indispensable for human knowledge, reason is equally crucial for organizing that experience into coherent understanding. Consequently, he concluded that both rational faculties and empirical data are essential for the acquisition of human knowledge. Similarly, Kant maintained that it was erroneous to conceive of thought as solely analytical. He asserted that "a priori concepts do exist, but if they are to lead to the amplification of knowledge, they must be brought into relation with empirical data."
Contemporary rationalism
"Rationalism" as a general philosophical designation is now less common; instead, various specialized forms of rationalism are recognized. For instance, Robert Brandom employs the terms "rationalist expressivism" and "rationalist pragmatism" to characterize elements of his work in Articulating Reasons. He also identified "linguistic rationalism"—the assertion that propositional content "are essentially what can serve as both premises and conclusions of inferences"—as a central tenet of Wilfred Sellars's philosophy.
Beyond formal academic philosophy, certain members of online communities associated with LessWrong and Slate Star Codex have adopted the designations "rationalists" or the "rationalist community," referring to rationality rather than the philosophical doctrine of rationalism. Critics, including Timnit Gebru, have similarly employed the term in this context.
Critiques
American psychologist William James critiqued rationalism for its perceived detachment from reality. James further argued that rationalism depicted the universe as a closed system, a perspective that diverged from his own conception of the universe as an open system.
Advocates of emotional choice theory challenge rationalism by leveraging recent discoveries in emotion research from psychology and neuroscience. They highlight that the rationalist framework typically posits decision-making as a conscious, reflective process driven by thoughts and beliefs, assuming individuals make choices through calculation and deliberation. Nevertheless, extensive neuroscientific research indicates that only a minor fraction of brain activity occurs at the level of conscious reflection, with the predominant portion comprising unconscious evaluations and emotions. These critics assert that rationalism has largely overlooked the crucial role of emotions in decision-making. Furthermore, emotional choice theorists argue that the rationalist paradigm struggles to integrate emotions into its models due to its inability to account for their social dimension. While emotions are experienced individually, psychologists and sociologists have demonstrated that emotions are inseparable from their social contexts. Emotions are intrinsically linked to individuals' social norms and identities, aspects generally excluded from conventional rationalist explanations. Emotional choice theory aims to encompass the social, physiological, and dynamic aspects of emotions, offering a unified action model to structure, elucidate, and forecast how emotions influence decision-making.
References
References
Sources
Primary Sources
- Descartes, René (1637), Discourse on the Method.
- Spinoza, Baruch (1677), Ethics.
- Leibniz, Gottfried (1714), Monadology.
- Kant, Immanuel (1781/1787), Critique of Pure Reason.
Secondary Sources
- Audi, Robert (ed., 1999), The Cambridge Dictionary of Philosophy, Cambridge University Press, Cambridge, 1995. Second edition, 1999.
- Baird, Forrest E.; Walter Kaufmann (2008). From Plato to Derrida. Upper Saddle River, NJ: Pearson Prentice Hall. ISBN 978-0131585911.
- Douglas, Alexander X.: Spinoza and Dutch Cartesianism: Philosophy and Theology. (Oxford: Oxford University Press, 2015)
- Fischer, Louis (1997). The Life of Mahatma Gandhi. HarperCollins. pp. 306–307. ISBN 0006388876.Zalta, Edward N. (ed.). "Rationalism vs. Empiricism." Stanford Encyclopedia of Philosophy. ISSN 1095-5054. OCLC 429049174.
- Zalta, Edward N. (ed.). "Rationalism vs. Empiricism". Stanford Encyclopedia of Philosophy. ISSN 1095-5054. OCLC 429049174.Homan, Matthew. "Continental Rationalism." In Fieser, James; Dowden, Bradley (eds.). Internet Encyclopedia of Philosophy. ISSN 2161-0002. OCLC 37741658.Lennon, Thomas M.; Dea, Shannon. "Continental Rationalism." In Zalta, Edward N. (ed.). Stanford Encyclopedia of Philosophy. ISSN 1095-5054. OCLC 429049174.Source: TORIma Academy Archive