What Is Rationalism? – The Spiritual Life

Posted: June 13, 2021 at 12:24 pm

In philosophy,rationalismis theepistemologicalview that regardsreasonas the chief source and test of knowledge[1]or any view appealing to reason as a source of knowledge or justification.[2]More formally, rationalism is defined as amethodologyor atheoryin which the criterion of the truth is not sensory but intellectual anddeductive.[3]

In an old controversy, rationalism was opposed toempiricism, where the rationalists believed that reality has an intrinsically logical structure. Because of this, the rationalists argued that certain truths exist and that the intellect can directly grasp these truths. That is to say, rationalists asserted that certain rational principles exist inlogic,mathematics,ethics, andmetaphysicsthat are so fundamentally true that denying them causes one to fall into contradiction. The rationalists had such a high confidence in reason that empirical proof and physical evidence were regarded as unnecessary to ascertain certain truths in other words, there are significant ways in which our concepts and knowledge are gained independently of sense experience.[4]

Different degrees of emphasis on this method or theory lead to a range of rationalist standpoints, from the moderate position that reason has precedence over other ways of acquiring knowledge to the more extreme position that reason is the unique path to knowledge.[5]Given a pre-modern understanding of reason, rationalism is identical tophilosophy, theSocraticlife of inquiry, or the zetetic (skeptical) clear interpretation of authority (open to the underlying or essential cause of things as they appear to our sense of certainty). In recent decades,Leo Strausssought to revive Classical Political Rationalism as a discipline that understands the task of reasoning, not as foundational, but asmaieutic.In the 17th-century Dutch Republic, the rise of early modern-period rationalismas a highly systematic school of philosophy in its own right for the first time in historyexerted an immense and profound influence on modern Western thought in general,[6][7]with the birth of two influential rationalisticphilosophical systemsofDescartes[8][9] (who spent most of his adult life in the Dutch Republic in the period 16281649 and despite frequent moves, he wrote all his major work during his 20-plus years in theUnited Provinces) andSpinozanamely CartesianismandSpinozism. It was the 17th-century arch-rationalistslike Descartes, Spinoza andLeibnizwho have given the Age of Reason its name and place in history.[30]

In politics, rationalism, since the Enlightenment, historically emphasized a politics of reason centered upon rational choice, utilitarianism, secularism, and irreligion[31] the latter aspectsantitheismwas later softened by the adoption of pluralistic methods practicable regardless of religious or irreligious ideology.[32]In this regard, the philosopherJohn Cottingham[33]noted how rationalism, amethodology, became socially conflated withatheism, aworldview:

In the past, particularly in the 17th and 18th centuries, the term rationalist was often used to refer to free thinkers of an anti-clerical and anti-religious outlook, and for a time the word acquired a distinctly pejorative force (thus in 1670 Sanderson spoke disparagingly of a mere rationalist, that is to say in plain English an atheist of the late edition). The use of the label rationalist to characterize a world outlook which has no place for the supernatural is becoming less popular today; terms like humanist or materialist seem largely to have taken its place. But the old usage still survives.

Rationalism is often contrasted withempiricism. Taken very broadly, these views are not mutually exclusive, since a philosopher can be both rationalist and empiricist.[2]Taken to extremes, the empiricist view holds that all ideas come to usa posteriori, that is to say, through experience; either through the external senses or through such inner sensations as pain and gratification. The empiricist essentially believes that knowledge is based on or derived directly from experience. The rationalist believes we come to knowledgea priori through the use of logic and is thus independent of sensory experience. In other words, asGalen Strawsononce wrote, you can see that it is true just lying on your couch. You dont have to get up off your couch and go outside and examine the way things are in the physical world. You dont have to do any science.[34]Between both philosophies, the issue at hand is the fundamental source of human knowledge and the proper techniques for verifying what we think we know. Whereas both philosophies are under the umbrella ofepistemology, their argument lies in the understanding of the warrant, which is under the wider epistemic umbrella of thetheory of justification.

The theory of justification is the part ofepistemologythat attempts to understand the justification ofpropositionsandbeliefs. Epistemologists are concerned with various epistemic features of belief, which include the ideas ofjustification, warrant,rationality, andprobability. Of these four terms, the term that has been most widely used and discussed by the early 21st century is warrant. Loosely speaking, justification is the reason that someone (probably) holds a belief.

If A makes a claim, and B then casts doubt on it, As next move would normally be to provide justification. The precise method one uses to provide justification is where the lines are drawn between rationalism and empiricism (among other philosophical views). Much of the debate in these fields are focused onanalyzingthe nature of knowledge and how it relates to connected notions such astruth,belief, andjustification.

At its core, rationalism consists of three basic claims. For one to consider themselves a rationalist, they must adopt at least one of these three claims: the intuition/deduction thesis, the innate knowledge thesis, or the innate concept thesis. In addition, rationalists can choose to adopt the claims of Indispensability of Reason and or the Superiority of Reason although one can be a rationalist without adopting either 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.[35]

Generally speaking, intuition isa prioriknowledge or experiential belief characterized by its immediacy; a form of rational insight. We simply see something in such a way as to give us a warranted belief. Beyond that, the nature of intuition is hotly debated.

In the same way, generally speaking, deduction is the process ofreasoningfrom one or more generalpremisesto reach a logically certain conclusion. Using validarguments, we can deduce from intuited premises.

For example, when we combine both concepts, we can intuit that the number three is prime and that it is greater than two. We then deduce from this knowledge that there is a prime number greater than two. Thus, it can be said that intuition and deduction combined to provide us witha prioriknowledge we gained this knowledge independently of sense experience.

Empiricists such asDavid Humehave been willing to accept this thesis for describing the relationships among our own concepts.[35]In this sense, empiricists argue that we are allowed to intuit and deduce truths from knowledge that has been obtaineda posteriori.

By injecting different subjects into the Intuition/Deduction thesis, we are able to generate different arguments. Most rationalists agree mathematics is knowable by applying the intuition and deduction. Some go further to include ethical truths into the category of things knowable by intuition and deduction. Furthermore, some rationalists also claim metaphysics is knowable in this thesis.

In addition to different subjects, rationalists sometimes vary the strength of their claims by adjusting their understanding of the warrant. Some rationalists understand warranted beliefs to be beyond even the slightest doubt; others are more conservative and understand the warrant to be belief beyond a reasonable doubt.

Rationalists also have different understanding and claims involving the connection between intuition and truth. Some rationalists claim that intuition is infallible and that anything we intuit to be true is as such. More contemporary rationalists accept that intuition is not always a source of certain knowledge thus allowing for the possibility of a deceiver who might cause the rationalist to intuit a false proposition in the same way a third party could cause the rationalist to have perceptions of nonexistent objects.

Naturally, the more subjects the rationalists claim to be knowable by the Intuition/Deduction thesis, the more certain they are of their warranted beliefs, and the more strictly they adhere to the infallibility of intuition, the more controversial their truths or claims and the more radical their rationalism.[35]

To argue in favor of this thesis,Gottfried Wilhelm Leibniz, a prominent German philosopher, says, 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[36]


We have knowledge of some truths in a particular subject area, S, as part of our rational nature.[37]

The Innate Knowledge thesis is similar to the Intuition/Deduction thesis in the regard that both theses claimknowledgeis gaineda priori. The two theses go their separate ways when describing how that knowledge is gained. As the name, and the rationale, suggests, the Innate Knowledge thesis claims knowledge is simply part of our rational nature. Experiences can trigger a process that allows this knowledge to come into our consciousness, but the experiences dont provide us with the knowledge itself. The knowledge has been with us since the beginning and the experience simply brought into focus, in the same way a photographer can bring the background of a picture into focus by changing the aperture of the lens. The background was always there, just not in focus.

This thesis targets a problem with the nature of inquiry originally postulated byPlatoinMeno. Here, Plato asks about inquiry; how do we gain knowledge of a theorem in geometry? We inquire into the matter. Yet, knowledge by inquiry seems impossible.[38]In other words, If we already have the knowledge, there is no place for inquiry. If we lack the knowledge, we dont know what we are seeking and cannot recognize it when we find it. Either way we cannot gain knowledge of the theorem by inquiry. Yet, we do know some theorems.[37]The Innate Knowledge thesis offers a solution to thisparadox. By claiming that knowledge is already with us, eitherconsciouslyorunconsciously, a rationalist claims we dont really learn things in the traditional usage of the word, but rather that we simply bring to light what we already know.


We have some of the concepts we employ in a particular subject area, S, as part of our rational nature.[39]

Similar to the Innate Knowledge thesis, the Innate Concept thesis suggests that some concepts are simply part of our rational nature. These concepts area prioriin nature and sense experience is irrelevant to determining the nature of these concepts (though, sense experience can help bring the concepts to ourconscious mind).

Some philosophers, such asJohn Locke(who is considered one of the most influential thinkers of theEnlightenmentand anempiricist) argue that the Innate Knowledge thesis and the Innate Concept thesis are the same.[40]Other philosophers, such asPeter Carruthers, argue that the two theses are distinct from one another. As with the other theses covered under the umbrella of rationalism, the more types and greater number of concepts a philosopher claims to be innate, the more controversial and radical their position; 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. Since we do not experience perfect triangles but do experience pains, our concept of the former is a more promising candidate for being innate than our concept of the latter.[39]

In his book,Meditations on First Philosophy,[41] Ren Descartes postulates three classifications for our ideas when he says, 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.[42]

Adventitious ideas are those concepts that we gain through sense experiences, ideas such as the sensation of heat, because they originate from outside sources; transmitting their own likeness rather than something else and something you simply cannotwillaway. Ideas invented by us, such as those found inmythology,legends, andfairy talesare created by us from other ideas we possess. Lastly, innate ideas, such as our ideas ofperfection, are those ideas we have as a result of mental processes that are beyond what experience can directly or indirectly provide.

Gottfried Wilhelm Leibnizdefends the idea of innate concepts by suggesting the mind plays a role in determining the nature of concepts, to explain this, he likens the mind to a block of marble in theNew Essays on Human Understanding, This is why I have taken as an illustration a block of veined marble, rather than a wholly uniform block or blank tablets, that is to say what is called tabula rasa in the language of the philosophers. For if the soul were like those blank tablets, truths would be in us in the same way as the figure of Hercules is in a block of marble, when the marble is completely indifferent whether it receives this or some other figure. But if there were veins in the stone which marked out the figure of Hercules rather than other figures, this stone would be more determined thereto, and Hercules would be as it were in some manner innate in it, although labour would be needed to uncover the veins, and to clear them by polishing, and by cutting away what prevents them from appearing. It is in this way that ideas and truths are innate in us, like natural inclinations and dispositions, natural habits or potentialities, and not like activities, although these potentialities are always accompanied by some activities which correspond to them, though they are often imperceptible.[43]

The three aforementioned theses of Intuition/Deduction, Innate Knowledge, and Innate Concept are the cornerstones of rationalism. To be considered a rationalist, one must adopt at least one of those three claims. The following two theses are traditionally adopted by rationalists, but they arent essential to the rationalists position.

The indispensability of reason thesishas the following rationale, The knowledge we gain in subject area,S, by intuition and deduction, as well as the ideas and instances of knowledge inSthat are innate to us, could not have been gained by us through sense experience.[1]In short, this thesis claims that experience cannot provide what we gain from reason.

The superiority of reason thesishas the following rationale, The knowledge we gain in subject areaSby intuition and deduction or have innately is superior to any knowledge gained by sense experience.[1]In other words, this thesis claims reason is superior to experience as a source for knowledge.

In addition to the following claims, rationalists often adopt similar stances on other aspects of philosophy. Most rationalists reject skepticism for the areas of knowledge they claim are knowablea priori. Naturally, when you claim some truths are innately known to us, one must reject skepticism in relation to those truths. Especially for rationalists who adopt the Intuition/Deduction thesis, the idea of epistemic foundationalism tends to crop up. This is the view that we know some truths without basing our belief in them on any others and that we then use thisfoundational knowledgeto know more truths.[1]

Rationalism as an appeal to human reason as a way of obtaining knowledge has a philosophical history dating from antiquity. Theanalyticalnature of much of philosophical enquiry, the awareness of apparentlya prioridomains of knowledge such as mathematics, combined with the emphasis of obtaining knowledge through the use of rational faculties (commonly rejecting, for example, directrevelation) have made rationalist themes very prevalent in the history of philosophy.

Since the Enlightenment, rationalism is usually associated with the introduction of mathematical methods into philosophy as seen in the works ofDescartes,Leibniz, andSpinoza.[3]This is commonly calledcontinental rationalism, because it was predominant in the continental schools of Europe, whereas in Britainempiricismdominated.

Even then, the distinction between rationalists and empiricists was drawn at a later period and would not have been recognized by the philosophers involved. Also, the distinction between the two philosophies is not as clear-cut as is sometimes suggested; for example, Descartes and Locke have similar views about the nature of human ideas.[4]

Proponents of some varieties of rationalism argue that, starting with foundational basic principles, like the axioms ofgeometry, one coulddeductivelyderive the rest of all possible knowledge. The philosophers who held this view most clearly wereBaruch SpinozaandGottfried Leibniz, whose attempts to grapple with the epistemological and metaphysical problems raised by Descartes led to a development of the fundamental approach of rationalism. Both Spinoza and Leibniz asserted that,in principle, all knowledge, including scientific knowledge, could be gained through the use of reason alone, though they both observed that this was not possiblein practicefor human beings except in specific areas such asmathematics. On the other hand, Leibniz admitted in his bookMonadologythat we are all mereEmpiricsin three fourths of our actions.[5]

Detail of Pythagoras with a tablet of ratios, numbers sacred to the Pythagoreans, fromThe School of AthensbyRaphael.Vatican Palace,Vatican City,

Although rationalism in its modern form post-dates antiquity, philosophers from this time laid down the foundations of rationalism. In particular, the understanding that we may be aware of knowledge available only through the use of rational thought.

Pythagoras was one of the first Western philosophers to stress rationalist insight.[44]He is often revered as a greatmathematician,mysticandscientist, but he is best known for thePythagorean theorem, which bears his name, and for discovering the mathematical relationship between the length of strings on lute and the pitches of the notes. Pythagoras believed these harmonies reflected the ultimate nature of reality. He summed up the implied metaphysical rationalism in the words All is number. It is probable that he had caught the rationalists vision, later seen byGalileo(15641642), of a world governed throughout by mathematically formulable laws.[44]It has been said that he was the first man to call himself a philosopher, or lover of wisdom.[45]

Plato held rational insight to a very high standard, as is seen in his works such asMenoandThe Republic. He taught on theTheory of Forms(or the Theory of Ideas)[46][47][48]which asserts that the highest and most fundamental kind of reality is not the material world of changeknown to us through sensation, but rather the abstract, non-material (butsubstantial) world of forms (or ideas).[49]For Plato, these forms were accessible only to reason and not to sense.[44]In fact, it is said that Plato admired reason, especially ingeometry, so highly that he had the phrase Let no one ignorant of geometry enter inscribed over the door to his academy.[50]

Aristotles main contribution to rationalist thinking was the use ofsyllogisticlogic and its use in argument. Aristotle defines 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.[51]Despite this very general definition, Aristotle limits himself to categorical syllogisms which consist of threecategorical propositionsin his workPrior Analytics.[52]These included categoricalmodalsyllogisms.[53]

Although the three great Greek philosophers disagreed with one another on specific points, they all agreed that rational thought could bring to light knowledge that was self-evident information that humans otherwise couldnt know without the use of reason. After Aristotles death, Western rationalistic thought was generally characterized by its application to theology, such as in the works ofAugustine, the Islamic philosopherAvicennaand Jewish philosopher and theologianMaimonides. One notable event in the Western timeline was the philosophy ofThomas Aquinaswho attempted to merge Greek rationalism and Christian revelation in the thirteenth-century.[44]

Early modern rationalism has its roots in the 17th-centuryDutch Republic,[54]with some notable intellectual representatives likeHugo Grotius,[55]Ren Descartes, andBaruch Spinoza.

French thinker Ren Descartes proposed several arguments that could be termed ontological.

Descartes was the first of the modern rationalists and has been dubbed the Father of Modern Philosophy. Much subsequentWestern philosophyis a response to his writings,[56][57][58]which are studied closely to this day.

Descartes thought that only knowledge of eternal truths including the truths of mathematics, and the epistemological and metaphysical foundations of the sciences could be attained by reason alone; other knowledge, the knowledge of physics, required experience of the world, aided by thescientific method. He also argued that althoughdreamsappear as real assense experience, these dreams cannot provide persons with knowledge. Also, since conscious sense experience can be the cause of illusions, then sense experience itself can be doubtable. As a result, Descartes deduced that a rational pursuit of truth should doubt every belief about sensory reality. He elaborated these beliefs in such works asDiscourse on Method,Meditations on First Philosophy, andPrinciples of Philosophy. Descartes developed a method to attain truths according to which nothing that cannot be recognised by the intellect (orreason) can be classified as knowledge. These truths are gained without any sensory experience, according to Descartes. Truths that are attained by reason are broken down into elements that intuition can grasp, which, through a purely deductive process, will result in clear truths about reality.

Descartes therefore argued, as a result of his method, that reason alone determined knowledge, and that this could be done independently of the senses. For instance, his famous dictum,cogito ergo sumor I think, therefore I am, is a conclusion reacheda priorii.e., prior to any kind of experience on the matter. The simple meaning is that doubting ones existence, in and of itself, proves that an I exists to do the thinking. In other words, doubting ones own doubting is absurd.[59]This was, for Descartes, an irrefutable principle upon which to ground all forms of other knowledge. Descartes posited a metaphysicaldualism, distinguishing between the substances of the human body (res extensa) and themindor soul (res cogitans). This crucial distinction would be left unresolved and lead to what is known as themind-body problem, since the two substances in the Cartesian system are independent of each other and irreducible.

In spite of his early death, Spinoza exerted a profound influence onphilosophy in the Age of Reason.[60][61][62]He is often considered one of three most remarkable rationalists of modern Western thought, along with Descartes and Leibniz.

The philosophy ofBaruch Spinozais a systematic, logical, rational philosophy developed in seventeenth-centuryEurope.[63][64][65]Spinozas philosophy is a system of ideas constructed upon basic building blocks with an internal consistency with which he tried to answer lifes major questions and in which he proposed that God exists only philosophically.[65][66]He was heavily influenced byDescartes,[67]Euclid[66]andThomas Hobbes,[67]as well as theologians in the Jewish philosophical tradition such asMaimonides.[67]But his work was in many respects a departure from theJudeo-Christiantradition. Many of Spinozas ideas continue to vex thinkers today and many of his principles, particularly regarding theemotions, have implications for modern approaches topsychology. To this day, many important thinkers have found Spinozas geometrical method[65]difficult to comprehend:Goetheadmitted that he found this concept confusing. Hismagnum opus,Ethics, contains unresolved obscurities and has a forbidding mathematical structure modeled on Euclids geometry.[66]Spinozas philosophy attracted believers such asAlbert Einstein[68]and much intellectual attention.[69][70][71][72][73]

Main article:Gottfried Leibniz

Leibniz was the last major figure of seventeenth-century rationalism who contributed heavily to other fields such as metaphysics, epistemology, logic, mathematics, physics, jurisprudence, and the philosophy of religion; he is also considered to be one of the last universal geniuses.[74]He did not develop his system, however, independently of these advances. Leibniz rejected Cartesian dualism and denied the existence of a material world. In Leibnizs view there are infinitely many simple substances, which he called monads (which he derived directly fromProclus).

Leibniz developed his theory of monads in response to both Descartes andSpinoza, because the rejection of their visions forced him to arrive at his own solution. Monads are the fundamental unit of reality, according to Leibniz, constituting both inanimate and animate objects. These units of reality represent the universe, though they are not subject to the laws of causality or space (which he called well-founded phenomena). Leibniz, therefore, introduced his principle ofpre-established harmonyto account for apparent causality in the world.

Kant is one of the central figures of modernphilosophy, and set the terms by which all subsequent thinkers have had to grapple. He argued that human perception structures natural laws, and that reason is the source of morality. His thought continues to hold a major influence in contemporary thought, especially in fields such as metaphysics, epistemology, ethics, political philosophy, and aesthetics.[75]

Kant named his brand of epistemology Transcendental Idealism, and he first laid out these views in his famous workThe Critique of Pure Reason. In it he argued that there were fundamental problems with both rationalist and empiricist dogma. To the rationalists he argued, broadly, that pure reason is flawed when it goes beyond its limits and claims to know those things that are necessarily beyond the realm of all possible experience: theexistence of God, free will, and the immortality of the human soul. Kant referred to these objects as The Thing in Itself and goes on to argue that their status as objects beyond all possible experience by definition means we cannot know them. To the empiricist he argued that while it is correct that experience is fundamentally necessary for human knowledge, reason is necessary for processing that experience into coherent thought. He therefore concludes that both reason and experience are necessary for human knowledge. In the same way, Kant also argued that it was wrong to regard thought as mere analysis. In Kants views,a prioriconcepts do exist, but if they are to lead to the amplification of knowledge, they must be brought into relation with empirical data.[76]

Rationalism has become a rarer labeltout courtof philosophers today; rather many different kinds of specialised rationalisms are identified. For example,Robert Brandomhas appropriated the terms rationalist expressivism and rationalist pragmatism as labels for aspects of his programme inArticulating Reasons, and identified linguistic rationalism, the claim that the contents of propositions are essentially what can serve as both premises and conclusions of inferences, as a key thesis ofWilfred Sellars.[77]

Rationalism was criticized by William Jamesfor being out of touch with reality. James also criticized rationalism for representing the universe as a closed system, which contrasts to his view that the universe is an open system.[78]

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What Is Rationalism? - The Spiritual Life

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