RATIONALISM – All you want to know

The seeds of rationalism have been firmly implanted in the Western world since at least the time of Plato. In the Middle Ages the cause was advanced by thinkers like Avicenna and scholastics like Duns Scotus. But the movement flowered in the modern triumvirate of Descartes, Spinoza, and Leibniz. Rationalism is characterized by its stress on the innate or a priori ability of human reason to know truth. Basically, rationalists hold that what is knowable or demonstrable by human reason is true.

An Exposition of Rationalism

Rationalism can be most easily understood by contrast with empiricism. The former stresses the mind in the knowing process and the latter lays emphasis on the senses. In the ancient world these emphases were found respectively in Plato and Aristotle. In modern times Descartes, Spinoza, and Leibniz are the chief exponents of rationalism; whereas Locke, Berkeley, and Hume are the prime examples of empiricism.

Along with its stress on the mind, rationalism holds to an a priori aspect to human knowledge, that is, something independent of sense experience. By contrast empiricists stress the a posteriori, or what comes through empirical experience. In like manner rationalists argue for innate ideas or principles, whereas empiricists believe that the mind is a tabula rasa or blank slate on which sense experience writes its impressions.

It is not uncommon for empiricism to lead to skepticism or ma-terialism, as in Hume and Hobbes. But rationalists tend to argue for the existence of God. Characteristic of a rationalist’s approach to God is the ontological argument from the idea of a perfect or necessary Being. However, empiricists who are theists tend to support their belief in God with the cosmological argument from the world to a cause beyond the world.

Perhaps the best way to understand rationalism is to see how it unfolded in its three major representatives in the modern world. Each has his distinctiveness but all exemplify the movement generally.

René Descartes (1596–1650)

Amid a period of increasing skepticism and doubt, Descartes felt called to bring certainty into philosophy. Since in Descartes’ day mathematics and particularly geometry held out most promise in this direction, Descartes applied the mathematical method to human reasoning. The result was what may be called a geometric epistemology. In order to arrive at demonstrable conclusions one must have unquestioned premises or axioms and from these he must deduce logically irrefutable conclusions.

But where is one to find these archimedean axioms in the flux of doubt? Descartes’ answer to this is both fascinating and illustrative of a classic rationalistic move. Doubt is a negative form of thought. And the more we doubt, the more certain we are of one thing, namely, that we are doubting. Complete doubt would bring complete certainty that one was thinking.

I doubt; therefore, I am thinking. But if one is thinking, he must be a thinking thing. Thus he moves from the dubito to the cogito to sum, from “I doubt” to “I think” to “I am.” The indubitable starting point or axiom is that one is both a doubting and a thinking being.¹

The mind then is a thinking thing and this cannot be doubted. But what of the body? According to Descartes the body is an extended thing, and this can be doubted. The senses deceive us and we could be merely dreaming about our body and the physical world. Indeed a malevolent demon may be deceiving me about the world. Just how Descartes overcomes this sensory doubt is an instructive lesson in a classic rationalistic move.

Since the only thing of which he is certain is the existence of his own mind, Descartes moves next to prove the existence of God. Then, on the grounds that God would not deceive us, Descartes attempts to demonstrate the existence of an external world of bodies.

Descartes offers two proofs for God and both are rationalistic. His a posteriori proof begins in doubt and thought.² I doubt. But if I doubt, I am imperfect; for a lack in knowledge is an imperfection. But if I know what is imperfect, I must have knowledge of the perfect; otherwise, I would not know it is not-perfect.

However, knowledge of the perfect cannot arise from an imperfect mind, since there cannot be an imperfect source or basis of what is perfect. Therefore, there must be a perfect Mind (God) who is the origin of the idea of perfection I have. The rationalistic character of this argument is not difficult to detect. The proof begins in the mind, then proceeds by a rational deduction to the conclusion that a perfect Mind exists.

The second proof Descartes offers is an a priori ontological argument in the tradition of Anselm. It may be summarized as follows.³ Whatever is necessary to the essence of a thing cannot be absent from that thing. For example, a triangle must have three sides. Devoid of three sides it would not be a triangle. Now existence or being is necessary to the nature of a necessary Being.

Without existence, it would not be by nature a necessary existent. It follows then that a necessary Being must necessarily exist. For if it did not exist it would not be by nature a necessary Being. God’s existence is logically necessary to affirm. Descartes’ other statement of this argument reveals the same rationalistic character. The idea of an absolutely perfect Being cannot be devoid of any perfection.

If it were, the idea would not be of what is absolutely perfect. But existence is a necessary element in the idea of an absolutely perfect Being. Anything lacking existence is lacking in perfection. Hence, an absolutely perfect Being must exist. For if it did not exist, the idea we have would not be of an absolutely perfect Being.

Not only is this second proof undertaken strictly in the realm of the mind, but it illustrates the innate, a priori stress on conceptual necessity in the reasoning process. God’s existence is conceptually or rationally inescapable.

Beneath the above argument lies a geometrical method of truth. Whatever is a clear and distinct idea (such as the indubitable ones) is true. (These are known intuitively; everything else is deducible from them.) Sensations and unclear ideas are not true. Errors arise not in the mind but in the will. Errors result when we judge to be true what the mind does not clearly know to be true. The corrective for error is found in four rules of valid thinking.

First, the rule of certainty states that only indubitably clear and distinct ideas should be accepted as true. Second, the rule of division affirms that problems must be reduced first to their simplest parts. Third, the rule of order declares that we must proceed in our reasoning from the simplest to the most complex. Finally, the rule of enumeration demands that we check and recheck each step of the argument to make sure no mistake has been made.⁴ By following this method Descartes was assured that error could be overcome and certainty could be attained in our knowledge of God.

Benedict Spinoza (1632–1677)

Spinoza was a younger contemporary of Descartes. Unlike Descartes his rationalistic method brought him to pantheistic conclusions rather than to Christian theism. Spinoza’s method, however, was even more rigidly geometric than Descartes’. He begins his work by setting forth eight definitions, seven axioms, and thirty-six propositions. Everything else is geometrically deduced from these.

The starting point of Spinoza is also different. Rather than beginning in methodological doubt in order to anchor the indubitable idea, Spinoza begins with the absolutely perfect idea of an absolutely perfect Being. He rejects both hearsay and conventional signs as guides to truth, along with the undisciplined experience of empiricists. These are unreliable in that they never attain the true nature or essence of things.

Even scientific inferences approach the essence of things only indirectly. For an essential knowledge of things we must exercise direct rational insight into the very essence of reality. In this way the mind can be united with the whole of nature and be healed of the injury of error. The most suitable method for engaging in this pursuit is by meditating on the absolutely perfect Idea of God. To begin anywhere short of the perfect Idea is to end in imperfection.⁵

For Spinoza error has four causes: the partial nature of our minds, which provide only fragmentary expressions of ideas; our imagination, which is affected by the physical senses and confuses us; our reasoning, which is often too abstract and general; and, above all, the failure to begin with the perfect Idea of God.

The geometric method is the remedy for error because it aids the weak mind, it is impersonal, and it yields conclusions that are proven (Q.E.D.). Furthermore, the more we feed on the perfect Idea, the more perfect we become. And the inner growth that results helps one distinguish clear ideas from confused sensations.

When Spinoza’s method is applied to God it yields for him the following results. First, in accordance with the traditional movement of the ontological proof, he argues that God must be conceived as a Being in and of himself, existing necessarily and independently.⁶ Anything less than this is inadequate and less than perfect. The first form of his argument runs as follows.

A necessary Being must necessarily exist unless there is a cause adequate to explain why it does not exist, for everything must have a cause either for its existence or for its nonexistence. But there clearly is no cause adequate to explain why a necessary Being does not exist. But since nothing either inside or outside a necessary Being could possibly annul it, there is no cause adequate to explain God’s nonexistence. Hence, God must necessarily exist.

Spinoza’s second argument for God begins with the affirmation that something necessarily exists.⁷ This he holds to be rationally inescapable, for even when one attempts to deny that anything exists he must affirm his own existence in so doing. But this existence must be either infinite or finite. And since everything must have a cause, there must be an adequate cause as to why this existence is not infinite. But in view of the fact that no finite existence can hinder it being infinite, it follows that this existence must be infinite.

The rationalistic method of Spinoza does not end in theism but in pantheism; for the infinite substance must be one, since it is impossible to have many infinite beings and finites are no more than many modes or moments of an infinite substance. All thoughts and attributes flow from the unity of this one substance with necessity just as 180° flows necessarily from the nature of a triangle.

And the effects (creation) are just as infinite as the cause (Creator). Indeed, the world with all its degrees of perfection (and corresponding imperfection) is both a necessary outflow from God and the best world possible. Viewing the world fragmentarily or segmentally leads to the misconception of evil. The world must be viewed as a whole, and the whole is both good and God in his multitudinous manifestations.

Gottfried Leibniz (1646–1716)

The last and perhaps most influential of the rationalistic theists was Leibniz. His particular brand of rationalism, as developed by Christian Wolff, has been the modern world’s chief example of rational theism. It is to the Leibniz-Wolffian theism that Kant reacted, and it has been subject to constant criticism since his day.

Unlike Descartes, Leibniz’ approach is not exclusively a rational one. He does not begin simply by an a priori analysis of ideas but with an examination of scientific findings from experience. He views the world as a grouping of simple natures (monads)⁸ in a calculus of combination possessing overall harmony by way of God.

However, Leibniz’ rationalism becomes apparent as he proceeds to argue for the existence of God by way of the principle of sufficient reason. The basis of Descartes’ rationalism was a clear or indubitable idea; Spinoza’s was the perfect Idea; but Leibniz bases his thoughts on God around the sufficient idea or reason.

There are several innate principles in the human mind that are not derived from the senses. First, the principle of sufficient reason says that nothing is without a reason; that is, everything has a reason or cause. This is the ground of all true propositions and it is known to be true analytically. One cannot deny it without using it. That is, he must have a sufficient reason for even denying the principle of sufficient reason, in which case he affirms it in the process of denying it.

Second, there is the law of contradiction or identity which affirms that something must be itself and cannot be other than itself. While sufficient reason regulates all truth, contradiction and identity determine or establish necessary truths. That is, identity is the sufficient reason for all necessary truths. Third, the principle of perfection or the principle of the best holds for all contingent truths, namely, since God is most perfect and wise he is morally (though not logically) obligated to create the best of all possible worlds. Finally, there are the principles of order including continuity and reaction.

In brief, they hold that the best world has no “gaps” but is a plenum (fulness) of different substances (monads). Breaks would violate the harmony of science. There is ultimate (mathematical) intelligibility in the universe. It is with the aid of these and other rational principles that Leibniz constructs his rationalistic theism.

The Leibnizian argument for the existence of God amply illustrates his rationalistic methodology in both his ontological and cosmological proofs for God’s existence. First, Leibniz argued (as had Anselm and Descartes) that if it is possible for an absolutely perfect Being to exist then it is necessary for it to exist.⁹ For by definition of its very nature an absolutely perfect Being cannot lack anything. So if it cannot lack anything it surely cannot lack existence.

And it is indeed possible or noncontradictory for God to possess absolutely all possible perfections, since perfections are irreducibly simple and therefore compatible qualities. That is, since there is no area of “overlap” with simple characteristics then there can be no conflict among them; they can all exist harmoniously in God. It must be concluded then that an absolutely perfect Being must exist; the very possibility of an absolutely perfect Being ensures its necessity. Reason demands God.

Leibniz’ cosmological type argument is likewise rationalistic.¹⁰. By experience we know that the entire observed universe is changing. But whatever changes lacks within itself the reason for its own existence. And yet there is a sufficient reason for everything either in itself or beyond itself. But since the world has not the sufficient reason for itself in itself in that it changes, there must be beyond the world a sufficient reason or cause for its existence.

Further, there cannot be an infinite regress of sufficient reasons, for the failure to reach an explanation is not an explanation. But the principle of sufficient reason demands that there be an explanation. Therefore, it is rationally necessary to conclude that there is a First Cause of the world which is its own sufficient reason for existing.

Several distinctively rationalistic aspects about this argument should be noted. First, although it begins with sense experience the conclusion is based on an analytical a priori principle of reason. Second, the principle of sufficent reason at the heart of the argument is held to be analytically true independent of experience. Third, “cause” is understood in terms of “reason” and “explanation” not distinctly as an ontological “ground” or “basis.” Fourth, notice also the difference between Leibniz’ principle of sufficient reason and, say, Aquinas’ principle of existential causality.

The latter says that only finite, changing, or contingent beings need a cause. The former says everything needs a reason. Further, Leibniz uses “cause” and “reason” somewhat interchangeably, whereas Aquinas considered a cause to be an ontological ground but not a rational explanation. Finally, by logical reduction Leibniz’ principle of sufficient reason leads to a Self-caused God, since everything must have a reason or cause including God. Hence, God must be his own cause. Aquinas’ principle of the cause of existence leads to an uncaused Cause.

For if only finite things and so forth need causes, an infinite being (God) would not need a cause but would be uncaused. The Leibnizian principle is distinctively rationalistic by comparison with the thomistic one. And it is noteworthy to observe that the fate of the cosmological argument in the modern world in the hands of Kant and followers has been largely identified with the Leibnizian rationalistic argument.

Stuart Hackett: Theistic Rationalism

Modern and contemporary Christian thought has not been without its strong strains of rationalism. A good bit of thomism has had strong rationalistic leanings since at least the time of Leibniz. Perhaps the best example of a contemporary evangelical is the work by Stuart Hackett, The Resurrection of Theism. ¹¹ Hackett entitles his view “rational empiricism,” but it might with equal justice be called “empirical rationalism” since he claims rational certainty for knowledge about God’s existence and nature derived from sense experience.

The Rejection of Kant’s Agnosticism. Hackett agrees with Kant that the content of all knowledge comes via the senses and that the form of knowledge is finalized by the a priori categories of the mind. He disagrees, however, with Kant’s agnostic conclusions. Kant was wrong in rejecting the preformation of the mind to reality. There must be a correspondence between the categories of the mind and reality, he argues, because the position which denies this “is self-contradictory and reduces to skepticism.”

For the assertion “that the categories yield no knowledge of things-in-themselves would be an unintelligible proposition if it were not false; since it assumes the very knowledge of noumenal reality which it denies.” It follows, then, that “the denial of the synthetic a priori is either self-contradictory or meaningless.” That is, contrary to empiricism which affirms that all contentful knowledge is based on sensation and cannot be known with certitude, it is logically necessary to maintain that the categories of the mind (such as unity and causality) are informative about reality.

In fact, “every attempt to derive the categories from the data of experience presupposes their use in the attempted derivation.” One cannot deny that there are universal and necessary truths, for “this proposition itself … is either true or false. If the proposition is false, it is refuted at once. Suppose then it is true,” Hackett continues, “in this case, since it asserts, or better denies, the predicate universally and necessarily, it is, by its own criterion, false—which is self-contradictory.”¹²

And since by logical necessity the opposite of the false must be true, it is logically necessary to conclude that the innate categories of the mind do inform man about the noumenal or real world.

Rational Proof for God’s Existence. Having laid the ground for theism in his rational realism, Hackett turns his attention to proving the existence of God. It is impossible to deny the existence of everything because the one making the denial “at least exists to effect the denial, which is therefore self-contradictory.” Now what exists is either an effect or not. If not, then we have already arrived at an absolutely necessary Being.

But if it is an effect, “its character and being must therefore, by definition, be determined by antecedent and contemporaneous existences external to itself.… But an infinite number of successive causes and effects … is rationally inconceivable.” It follows then that “whether a given entity is an effect or not, we rationally conclude the existence of an absolutely necessary being.”¹³

This argument is elaborated and defended with a great deal of rational sophistication, after which Hackett summarizes the important things about it. “In the first place, it rests upon that very a priori structure of rationality with which the mind approaches the experience and without which intelligible experience itself does not exist.” And “in the second place, the argument has likewise an a posteriori or existential premise; for it reasons to the existence of an absolutely necessary being from the granted reality of some particular entity of experience.”

Finally, “the sum of the whole matter is this: that rationality and experience have together established the existence of an absolutely infinite being that transcends the world of experience and is its only sufficient explanation.”¹⁴ In brief, it is rationally inescapable to conclude God’s existence, because it is logically necessary to conclude both that our minds correspond to reality and that there must be in reality an absolutely necessary Being (God).

Gordon Clark: Revelational Rationalism

There is yet another kind of evangelical rationalism. It claims no rationally inescapable arguments. Indeed, it disavows all such. “As a recourse for Christian theism,” writes Clark, “the cosmological argument is worse than useless. In fact Christians can be pleased at its failure, for if it were valid, it would prove a conclusion inconsistent with Christianity.”¹⁵ Hume and Kant put theistic rationalism to rest over one hundred fifty years ago.

The Need for Presuppositions. The failure of all philosophical attempts to establish truth either secular or religious points up the need for a Christian presupposition. “The various systems all fail on the two points at which failure is fatal. First, they do not furnish a systematic, consistent set of universal principles.” Second, “they give no guidance in making concrete decisions of everyday living.… Failing thus both theoretically and practically, the failure is complete.”¹⁶

From this Clark draws two conclusions: “The first is that no construction in philosophy is possible without some sort of presupposition or a priori equipment.” The second conclusion is “that the secular philosophers who use presuppositions have not selected those which can solve their problem.” To this Clark adds “a third conclusion, or at least an hypothesis for consideration. It is that revelation should be accepted as our axiom, seeing that other presuppositions have failed.”¹⁷

Testing the Christian Presupposition, Clark admits that the fact that “revelation should be accepted without proofs or reasons, undeduced from something admittedly true, seems odd when first proposed.” Nevertheless, he feels “it will not seem so odd … when the nature of axioms is kept in mind.” For “axioms, whatever they may be and in whatever subject they are used, are never deduced from more original principles.

They are always tested in another way.” Every philosopher makes a voluntary choice of his axioms. “Axioms, because they are axioms, cannot be deduced from or proved by previous theorems.” What we must ask with respect to the axiom of the prepositional revelation of Scripture is: “Does revelation make knowledge possible? Does revelation establish values and ethical norms? Does revelation give a theory of politics?

And are all these results consistent with one another?” In short, “we can judge the acceptability of an axiom by its success in producing a system.” Logical consistency is the essence of truth, and logical contradiction is the core of falsity.¹⁸

The Status and Defense of the Law of Noncontradiction. According to Clark, “the denial of the law of contradiction, or even the failure to establish it as a universal truth, was the downfall of secular philosophy.” Even the intelligibility of the Scriptures presupposes logic. But this does not mean that logic should be conceived as a prior or separate axiom from Scripture.

For logic is embedded in Scripture and Scripture is the logically consistent thoughts of God expressed in verbal form. In fact, John’s prologue should be translated, “In the beginning was Logic, and Logic was with God, and Logic was God.” This should not sound offensive to the Christian because the Word is the expression or thought of God. Therefore, “the law of contradiction is not to be taken as an axiom prior to or independent of God.

The law is God thinking.” In this sense, “if one should say that logic is dependent on God’s thinking, it is dependent only in the sense that it is the characteristic of God’s thinking.” It is not subsequent temporally “for God is eternal and there was never a time when God existed without thinking logically.” Hence, logic is to be considered as an activity of God’s mind.¹⁹

Clark believed “it is strange that anyone who thinks he is a Christian should deprecate logic.… The law of contradiction cannot be sinful” simply because man’s mind is fallen. “Quite the contrary, it is our violations of the law of contradiction that are sinful.” He asks, “Can such pious stupidity really mean that syllogism which is valid for us is invalid for God? If two plus two is four in our arithmetic, does God have a different arithmetic in which two and two make three or perhaps five?” Nonsense.

“To avoid this irrationalism, which of course is a denial of the divine image, we must insist that truth is the same for God and man.” For “if we know anything at all, what we must know must be identical with what God knows.… It is absolutely essential therefore to insist that there is an area of coincidence between God’s mind and our mind.”²⁰

The Relation of Scripture and Logic. Clark concludes that “since secular philosophy had failed to solve its problems, the alternative hypothesis of revelation, verbal communication, the Bible was proposed.” In this we may anticipate the relation of logic to the Scripture. “First of all, Scripture, the written words of the Bible, is the mind of God. What is said in Scripture is God’s thought.”

For “the Bible consists of thoughts, not paper; and the thoughts are the thoughts of the omniscient, infallible God.…” and, “as might be expected, if God has spoken, he has spoken logically. The Scripture therefore should and does exhibit logical organization.” Further, “this exhibition of the logic embedded in Scripture explains why Scripture rather than the law of contradiction is selected as the axiom.” For “this sine qua non is not sufficient to produce knowledge. Therefore the law of contradiction as such and by itself is not made the axiom of this argument.”

Even God is not the axiom for “ ‘God’ as an axiom, apart from Scripture, is just a name. We must specify which God.” Spinoza began with the axiom of a pantheistic God. Other axioms that define God in other ways are possible. “Therefore the Scripture is offered here as the axiom. This gives definiteness and content, without which axioms are useless. Thus it is that God, Scripture, and logic are tied together.”²¹

All non-Christian world views are ultimately self-contradictory. For example, skepticism refutes itself because it is internally self-contradictory. If skepticism is true, it is false. This “method of procedure stresses coherence or self-consistency, and the implication of each position must be traced out to the end. A reductio ad absurdum would be the test.” And if there seem to be two systems fairly coherent, then one must choose between them with regard to “the widest possible consistency.”

Of course, “no philosopher is perfect and no system can give man omniscience. But if one system can provide plausible solutions to many problems while another leaves too many questions unanswered, if one system tends less to skepticism and gives more meaning to life,” or “if one world view is consistent while others are self-contradictory, who can deny us, since we must choose, the right to choose the more promising first principle?” And this principle is for dark the axiom of prepositional relation in Scripture.

In short, the Bible is God’s thoughts expressed verbally, and God thinks logically and consistently. For logic is a characteristic of God’s thinking. Hence, the system that is ultimately consistent is ultimately true. But since only an omniscient mind can know this system is ultimately consistent, finite minds must choose the one that seems most coherent. Such, for Clark, is the system of Biblical Christianity.²²

Some Basic Tenets of Rationalism

Our concern here is not with a complete list and critique of rationalistic premises but simply with an evaluation of essential rationalistic methodology as it bears on establishing the truth or falsity of theism. In line with this purpose we may single out several central tenets of rationalistic epistemology.

Reality Is Rationally (i.e.. Mathematically) Analyzable. One of the central assumptions of modern rationalism, as of its Pythagorean and Platonic predecessors, is the belief in the union or communion of the mathematical and the metaphysical. That is to say, reality is analyzable by mathematical methods. The real is rational and the heart of rationality is mathematical identity.

There Are Innate Ideas or Principles. Certain truths are innate to the mind and known independently of experience. The precise number and nature of these may vary from rationalist to rationalist, but all would agree that the basic laws of logic, such as the law of noncontradiction, are known innately. Men are born with an a priori aspect of knowing that enables them to come to explicit knowledge of truth.

Without innate ideas or principles there would be no knowledge at all and certainly no demonstrations or proofs. The mind is not a tabula rasa; sense experience is parallel to or the occasion of intellectual knowledge but is not the cause or basis of it. Truth is based in the ideas or principles innate to the mind and not in the changing flux of sense experience.

Truth Is Derived by Deduction from Self-evident Principles. Another characteristic of modern rationalism is the use of geometric deductions based on intuitively known self-evident truths. The starting point is some apodictic axiom known innately by direct rational intuition. For Descartes it is the intuition of self-evidently clear and distinct ideas. For Spinoza it is insight into the perfect Idea of God and the axioms implied in that.

Leibniz held to intuitive first principles such as sufficient reason and identity. From these axioms one can proceed by logical mathematical deductions to necessary conclusions.

The Claim for Rational Certainty in Arguments for God. Common to modern rationalists is the claim of rational inescapability. God is known to exist not by scientific probability but by mathematical certainty. Spinoza did not blush to write Q.E.D., indicating that the proof was completed and the demonstration made. Neither Descartes nor Spinoza was embarrassed to claim rational certainty for their arguments.

God exists, they insisted, as necessarily as 180 degrees flows from the nature of a triangle. Leibniz too considered his argument as certain as the laws of thought.

The Rationally Inescapable Is the Real. Beneath the foregoing tenet of rationalism is an all-important proposition usually implied by the proponents and often missed by the opponents of rationalism, namely, the rationally inescapable is the real. That is, whatever is logically inescapable in the realm of thought about reality (or, God) is necessarily true.

The ontological argument is the classic case in point. In each case the hidden premise is that whatever is logically necessary is actually so. For if it is logically necessary to think of God as a necessary Existent, then it is actually true that he does necessarily exist.

Rationalists are sometimes unfairly criticized for holding that the rational is the real. This is not so. The rational is only the possibly real, but the rationally inescapable is the actually real. Mermaids are possible realities, since there is no contradiction in the concept or thought of them. But God is an actual reality because it would be a contradiction to deny his existence for a rationalist.

An Evaluation of Rationalism as a Method of Knowing God

There are some obvious problems with rationalism as a method of establishing truth, but there are some significant emphases that should not be overlooked. We will first center our attention on these positive features.

Valuable Strains in Rationalistic Thought

1. One of the more basic contributions of rationalism is its stress on the inescapability of the basic laws of thought. Unless the law of noncontradiction holds, then there is not even the most minimal possibility of meaning nor any hope for establishing truth. As a negative test for truth at least, the principle of noncontradiction is absolutely essential. Without this law, truth cannot be distinguished from falsity; all is equally true and false, which is to say nothing can be true.
2. The second contribution is sometimes overlooked by overzealous empiricists, namely, there must be an a priori dimension to knowledge. These need not be innate ideas but there must be at least some natural inclinations of the mind toward truth or toward the first principles of knowledge. If not, nothing could ever be known. But something is knowable; agnosticism is self-defeating (see Chapter One). Without some categories or at least capacities of the mind to know reality, the very possibility of truth would be nil. Even if all knowledge came through the senses it could not be known as true by the senses. There may be nothing in the mind that was not first in the senses, except the mind itself. And the mind must possess some innate or natural abilities of its own to engage in the pursuit of truth. This a priori contribution of rationalism is essential to any realistic epistemology.
3. Along with the first two contributions we must list another, namely, the rationalistic stress on the intelligibility and knowability of reality. Agnosticism is self-destructive; reality is not paradoxical and unknowable. There is a correspondence or adequation between the mind and being. The real is rational, even though the rational is not always real. There is no way of denying that thought relates to reality without, in that very thought, applying thought to reality. The rationalists rightly preserve the truth that reality is intelligible.

The Inadequacy of Rationalistic Methodology

Despite the significant and abiding contributions of some of its emphases, rationalism as a methodology for establishing truths about reality or the truths of theism is inadequate for several reasons.

1. First, it is based on an invalid move from thought to reality, from the possible to the actual. Just because something is thinkable does not make it actual. The thinkable describes only the realm of the possible and not necessarily that of the actual. What is not contradictory could possibly be true; what is contradictory could not possibly be true. That is, there could be centaurs (possible beings); there are humans (possible and actual beings); but there cannot be square circles (impossible beings). One may not legitimately move from the possible to the actual, from thought to reality.

At this point the rationalist might agree but insist that he is not moving merely from the logically possible to the actually real but from the logically necessary to the ontologically inescapable. If he so insists, two observations are pertinent. First, it is not logically necessary for a human being to exist. It is always at least logically possible for whatever contingent being that exists also not to exist.

One’s own existence may be actually undeniable, but this is something quite different from saying it is logically necessary. Logic does not determine existence; rather, it is reality that governs the nature of thought. Second, if the rationalist insists that at least in one case (viz., the argument for God) there is rational necessity that leads us to reality, then we mustpoint out the fallacy in the hidden premise in the ontological argument, namely, the contention that the rationally inescapable is the real. This leads to the next point.

2. Contrary to the central claim of traditional rationalism, the rationally inescapable is not the real. First of all, this claim assumes but does not prove—certainly not with rational inescapability—that something is real.²³ There is no purely logical justification for that claim. The arguments offered by rationalists reduce not to logical necessity but to actual undeniability. For example, if one attempts to deny that anything exists, he thereby affirms his own existence. But this does not at all imply that he exists with logical necessity. One’s own nonexistence is logically possible and the affirmation of one’s existence is actually unavoidable. But in no case is it logically necessary that one exist. Hence, the rationalist confuses actual undeniability with rational inescapability. There is no purely logically compelling reason for reality. No strictly rational proof is available for the existence of anything. It is a mistaken effort to contend that reality can be rationally proven.

The invalidity of the ontological argument is illustrative of the point being made here. Certainly, a triangle must be conceived as having three sides and, if a triangle exists, it must exist with three sides. But it is not logically necessary that any triangle exists anywhere. In like manner, it is logically necessary to predicate existence of a necessary Existent and, if such a Being exists, it must necessarily exist.

But it is not logically necessary for a necessary Being to exist any more than it is for a triangle to exist. Of course, if something exists, then the ontological argument takes on new strength; for if something exists it is possible that something necessarily exists. But the point here is that there is no purely logical way to eliminate the “if.” I know undeniably but not with logical necessity that I exist. And this is precisely the point at which the proponents of the ontological argument covertly borrow the fact of an undeniable existence in order to strengthen their argument.

They know that it is undeniable that something exists (viz., one’s self). And once it is thereby granted that something is real, they can move more easily toward proving that it is logically necessary that something exists. But even here their argument is misdirected. For God cannot be a logically necessary Being. If there is a God he would be an actually necessary Being, but it is confusing categories to make conceptual or rational necessity constituative of the reality of God.

Further, the ontological argument as such does not even prove that anything exists necessarily but only undeniably that something exists. It remains to be shown that this something is a necessary Being. And the ontological argument provides no rationally inescapable way of demonstrating that that which is, undeniably exists or entails a necessary Being.

One attempt to fill in the gap in logical necessity left by the ontological argument might be an appeal to a premise from the cosmological argument by arguing that there must be a sufficient reason for whatever exists (à la Leibniz). This would lead us ultimately to a necessary ground for whatever contingent beings exist. But even here there is a fatal flaw in the rationalist’s argument. For the principle of sufficient reason cannot be proved with logical necessity.

For it is possible to deny the principle of sufficient reason without involving a contradiction. For example, one can affirm that some things do not have a sufficient reason; and the world is one of them. Now whereas it would be contradictory to affirm that nothing has a sufficient reason including this very statement, nevertheless it is not contradictory to affirm that something(s) does not have sufficient reason. In point of fact, many theists (as Aquinas) claim precisely this about God: he has no sufficient reason or cause but is an uncaused cause.

In any event, there is no purely rational contradiction in denying the principle of sufficient reason of one’s self or of the world. And if it is logically possible that some things do not need a sufficient reason, then it is not logically necessary that God exists. Hence, even Leibniz’ cosmological proof imports a premise that lacks rational inescapability. Rationalism thus fails in its attempt at rationally apodictic certainty. It is logically possible that there is no God.

3. Growing out of the previous criticism is one final criticism of rationalism: it fails to demonstrate that its first principles are rationally necessary. As Aristotle said long before, first principles cannot be proved. Or, as Wittgenstein has noted, all justification must come to an end. If indeed, as Descartes claimed, there is a rational intuition of the basic axioms of thought from which all other deductive demonstrations proceed, then it is evident that there can be no demonstration of the basic axioms. But herein lies the problem. Not only did the rationalists offer no demonstration of their axioms, but they differed in their conception of them and even drew differing conclusions from them. It must be remembered that Spinoza “logically” deduced pantheism from his axioms, while Descartes and Leibniz “logically” deduced differing theisms from theirs. But the central point remains that rationalism cannot be completely rationalistic. All its rational processes begin with ideas or principles to which its proponents are committed without a logically necessary basis.

The point of this criticism can be focused by showing the circularity of a rationalistic attempt to prove the validity of the principle of contradiction. One cannot legitimately argue that the law of noncontradiction is valid because it is contradictory to deny it. For in that case he is using the law of noncontradiction as the basis of his proof of the law, which begs the whole question.

Likewise, one cannot meaningfully affirm that it is irrational to deny the first principles of rationalism. But if it is not necessarily contrary to reason to deny that rationalism is true, it is not rationally necessary to hold that rationalism is true. Herein lies the dilemma of rationalism: there is no strictly rational way to establish itself. There is both logical and historical evidence to support the thesis that rationalism is based in intuitivism and leads to either mysticism or, by way of reaction, to fideism.

4. Even the weaker form of Christian rationalism represented by Gordon Clark is insufficient as a test for truth. For as Clark admits, one would have to be omniscient in order to apply with certainty the logical consistency test for truth. Some systems seem equally consistent with their own presuppositions. And there is no way on purely rationalistic grounds to challenge those presuppositions, Clark, then, must choose between fideism and some other form of confirmation. Logic alone is at best a negative test for truth. That is, it is a test for falsity by way of internal inconsistency. Spinoza’s pantheism is as consistent with his axioms as Descartes’ theism is with his axioms. But since many opposing views may be internally noncontradictory and consistent with their own presuppositions, then logic alone is an insufficient test for truth.

Summary and Conclusion

The heart of rationalism is the thesis that the rationally inescapable is the real. Rationalistic theism holds that the existence of God can be demonstrated with logical necessity. We have seen that this is wrong for at least three reasons. First, logic is only a negative test for truth. It can eliminate what is false but cannot in and of itself establish what must be true. Logic can only demonstrate what is possibly real but not what is actually real.

Second, there are no rationally inescapable arguments for the existence of God because it is always logically possible that nothing ever existed including God. Of course, it is actually undeniable that something exists (e.g., my own existence is undeniable). But even here there is no logical necessity that I exist. My nonexistence is logically possible, as is that of the whole world and God. And if there is no logically necessary basis for either my existence or that of anything else, then it is not logically necessary to conceive the existence of anything including God.

Finally, there is no rationally inescapable way of establishing the first principles of reasoning. They are intuitive but nondemonstrated givens. Rationalism is without a necessary rational basis of its own. Hence, the existence of God cannot be demonstrated with logical necessity. If Christian theism is to be established as true, then some other test of truth must be found.

SELECT READINGS FOR RATIONALISM

Exposition of Rationalism

• Clark, Gordon. A Christian View of Men and Things.
• Descartes, René. Meditations.
• Hackett, Stuart. The Resurrection of Theism.
• Leibniz, Gottfried. Discourses on Metaphysics.
• Spinoza, Benedict. Ethics.

Evaluation of Rationalism

• Gurr, Edwin. The Principle of Sufficient Reason in Some Scholastic Systems: 1750–1900.
• Hume, David. An Enquiry Concerning Human Understanding.
• Montague, W. P. The Ways of Knowing, pt. I, chap. IV.
• Nash, Ronald. The Philosophy of Gordon Clark.

^[1]

¹ See Descartes, Meditations on the First Philosophy, I.

² Descartes, II.

³ Descartes, III.

⁴ Descartes, Discourse on Method, pt. II.

⁵ Spinoza, Ethics, pt. I, Proposition xi.

⁶ Spinoza.

⁷ Spinoza.

⁸ See Leibniz, Monadology, pp. 1–9.

⁹ Leibniz, pp. 40–45. Cf. Discourse on Metaphysics, xxiii.

¹⁰ Monadology, pp. 36–39

¹¹ Professor Hackett has since modified the claim that these arguments are rationally inescapable to something more like actual undeniability (see Chapter Eight).

¹² Stuart Hackett, The Resurrection of Theism, pp. 54, 60, 62, 65.

¹³ Hackett, pp. 194–95.

¹⁴ Hackett, pp. 202–3.

¹⁵ Gordon Clark, Religion, Reason, and Revelation, p. 41.

¹⁶ Ronald Nash, Philosophy of Gordon Clark, p. 54.

¹⁷ Clark, pp. 57–59.

¹⁸ Clark, pp. 59–60.

¹⁹ Clark, pp. 64, 67, 68.

²⁰ Clark, pp. 76, 77.

²¹ Clark, pp. 71, 72.

²² Gordon Clark, Christian View of Men and Things, pp. 30, 34.

²³ See my article, “The Missing Premise in the Ontological Argument,” Religious Studies IX, No. 3 (Sept. 1973).

^[1]Geisler, N. L. (1976). Christian apologetics. Includes index. (29). Grand Rapids: Baker Book House.

RATIONALISM – All you want to know