Piotr Gutawski is a student and instructor at the Catholic University of Lublin, Department of Philosophy, AI. Raclawickie 14,20-950 Lublin, POLAND. He is writing a dissertation on Hartshorne, and recently published an article, “Some Remarks on Charles Hartshorne’s Conceptions of Theology” in Charles Hartshorne ‘s Concept of God (Ed. Santiago Sia, Kluwer Academic Publishers, 1990).
The following article appeared in Process Studies, pp.1-9, Vol. 19, Number 1, Spring, 1990. Process Studies is published quarterly by the Center for Process Studies, 1325 N. College Ave., Claremont, CA 91711. Used by permission. This material was prepared for Religion Online by Ted and Winnie Brock.
SUMMARY
The author’s object is to show that Hartshorne overestimates the argumentative power of his rationalistic principles in the process of eliminating other philosophical positions, and that genuine empirical criteria are inevitable if metaphysics is going to be something more than pure speculation.
Charles Hartshorne presents himself and is presented by others as a strong rationalist. David Griffin thinks, however, that Hartshorne may be also called an empiricist. Rationalism may stand in opposition to empiricism, as for example in Descartes’ philosophy, but it doesn’t have to. It may be opposed primarily to mysticism or fideism (or voluntarism), finding itself in full conformity with empiricism, like 18th century French rationalism. Hartshorne’s critiques are directed mainly against mysticism and voluntarism and not against empiricism. What then is the reason for calling him a rationalist rather than an empiricist?
One of the reasons may lie in the fact that Hartshorne calls his concept of metaphysics a priori. But this only means, says Griffin, that metaphysical concepts "are prior not to all experience but only to particular, contingent aspects of experience" (CHPP 22). If so, Hartshorne’s metaphysics "is not unrelated to experience" and he may also be called an empiricist (CHPP 22). I think, however, that the main reason for describing Hartshorne as a rationalist is (or should be) his view concerning the criteria for philosophically valuable knowledge. Philosophically valuable knowledge means that which is true, universal, necessary and intersubjectively controllable. Both rationalists and empiricists can agree that reason is not opposed to experience. But the empiricist would add that the criterion of valuable knowledge is experience, and the rationalist that it is reason. For Hartshorne experience is the source of knowledge. In that sense he is, as are the majority of philosophers, a genetical empiricist (CSPM 31). But knowledge is philosophically valuable only and exclusively if it fulfills rationalistic criteria. And this element of his metaphilosophy should be, in my opinion, the decisive factor for calling Hartshorne a rationalist (strictly speaking a methodological rationalist) rather than an empiricist.
In this article I will argue that Hartshorne accepted rationalism in its extreme form because of methodological problems which an appeal to broadly conceived experience can cause for an advocate of the universalistic ideal of knowledge. I will also discuss some of Hartshorne’s metaphilosophical principles in the context of his expectations for their argumentative power. Eventually I will formulate some remarks about Hartshorne’s understanding of a priority and its relation to experience.
Traditionally experience was understood as meaning the direct knowledge acquired by (or type of cognition utilized by) our five senses. But many philosophers, not satisfied with such a narrow realm of direct knowledge, broadened the concept of experience to include some nonsensory types of cognition. In his doctoral thesis Hartshorne writes that philosophy "must rely above all upon the most profoundly empirical of all modes of apprehension -- the religious" (HEP 19). George Wolf once asked Hartshorne what had led him to write his book Philosophy and Psychology of Sensation. Hartshorne answered by telling him "a little story about how one day, as a young man, he stood on a cliff on the coast of France and beheld a scene of great natural beauty. Suddenly he saw ‘into the life of things’ and at that moment gained a sense of all of nature being alive and expressing feelings" (PB 167). The use of the term "see" (as into the nature of things) is very characteristic. Hartshorne uses it here not to refer to reasoning, not to discourse, but to direct cognition. The problem is how we can intersubjectively control this type of experience.
If your friend comes to you and says that there is an elephant in your living room, you may not believe him, but you have a very simple way to check if what he said is true or false. It is enough if you go there and see. There are, obviously, many difficulties in controlling our sensory perceptions, but they are small in comparison with controlling nonsensory experience. Imagine the same friend saying that God exists, or that he experienced God. But you are an atheist. How can you check if your friend is telling the truth, lying, or being deceived by a false interpretation of some exciting experience?
So, if somebody wants to maintain a broad concept of experience and the universalistic ideal of knowledge at the same time (as Hartshorne does), he cannot appeal to experience as the ultimate criterion of knowledge. One possible escape from this dilemma is to apply rationalistic criteria. Your friend might say: "Maybe you cannot check experientially whether God exists or not, but we can try to check the value of my insights indirectly. If we agree on rationalistic criteria for valuable knowledge, and that every idea is part of a broader system which ultimately constitutes a vision of the whole world, then we may evaluate the vision of the world with or without God, and we may hope that without appealing to experience we will reach a conclusion that one of the systems is less intelligible than the other." The whole procedure would then be strictly rationalistic. The main presupposition of this program is that there is a set of common and unquestionable principles in the domain of reason.
The problem I have sketched here was often discussed in philosophical literature from the 1930’s through 50’s, and later, in connection with the neopositivistic requirement that every meaningful proposition must either be a formal tautology or empirically verifiable. Later the criterion of propositional verification was transformed into the principle of falsification of theories. Hartshorne was very active in these discussions, trying to defend metaphysics as a legitimate cognitive enterprise. The pressure of epistemological standards established by minimalistic philosophies was extremely strong at that time, and any philosopher who wanted to be treated seriously in academic circles had to take them into account. I think Hartshorne’s extreme rationalism is -- to a certain extent -- the wound from that battle against neopositivists.
But there was also a different problem with the notion of experience which could have pushed Hartshorne in the direction of "untamed" rationalism. This was connected with the relation of experience to interpretation. It was a hope of many philosophers to find indubitable experiential knowledge upon which whole philosophical systems could be built. Descartes in the 18th century and Husserl in the 20th tried to reach such knowledge. In the beginning of the 19th century, however, some thinkers became convinced that pure, uninterpreted experience was only a dream, and that in fact every experience is already somehow interpreted. Philosophers who influenced Hartshorne the most shared this view. Whitehead, for example, writes ironically in Process and Reality: "If we desire a record of uninterpreted experience, we must ask a stone to record its autobiography" (PR 15/22). But if every experience is already interpreted it cannot be the ultimate criterion of philosophically valuable knowledge. One may try to substitute the notion of experience by the more complex notion of practice. It is also possible -- if somebody wants to maintain universalism -- to go in the direction of the rationalistic evaluation of experiences. It doesn’t matter then if these experiences are interpreted or not.
There could have been then various reasons for Hartshorne’s accepting radical rationalism. I have pointed out only two of them. Be that as it may, in 1948, in the article Rationalistic Criterion in Metaphysics Hartshorne writes: "The method logically appropriate to this program [i.e. the program of metaphysics] is to experiment with diverse definitions and alternative axioms or postulates, in search of a set -- if we are so lucky as to find it -- which can be given definite and consistent meaning" (RPM 438). And so "if, as rationalism holds, any coherent set of philosophical ideas must be true, it is quite unnecessary to start with self-evident ideas, and foolish to try to. No matter how we start, if we iron out the inconsistencies, and substitute meaning for meaninglessness, we are bound to reach the truth eventually" (RPM 439).1 There are many assumptions in Hartshorne’s program. One of them is that the structure of our thought is in congruence with the structure of reality (experience), and that if we know the first, then, by applying rationalistic principles, we can also know the second. This procedure may be compared to that of reconstructing the shape of a prehistoric animal on the basis of the imprint of its skeleton. Assuming that this imprint reflects the real skeleton (that the imprint is not distorted), we may reject those images of the animal which obviously violate the shape of the imprint. And we may also hope that only one theory will be fully compatible with our data.
What constitutes the "imprint" of a metaphysical backbone? Hartshorne believes that it is constituted by requirements of coherence, consistency, definite meaning, clarity, moderation, etc. Every philosophical theory that violates these rules must be rejected. "Suppose," he writes, "it could be proved that of the metaphysical systems which are prominent in the history of philosophy, all without exception contain elements which are either hopelessly vague or definitely absurd. I do not believe this proof is so difficult, not to say chimerical, a project as it will seem to some" (RPM 437).
I belong to those "some" who do not believe that such a proof is so simple. And one reason for this skepticism is that I do not think we have one clear "imprint" of a skeleton of metaphysics. Clarity, moderation, and even consistency are not univocal principles -- they may be understood in various ways. And even if they were univocal, they would constitute a metaphilosophical ideal for some philosophers but would be consciously rejected by others. The reasons for this rejection may be different: the nature of the metaphysical enterprise; the object of metaphysics; or conviction about limitations of our knowledge.
Even Hartshorne himself changed his position during his philosophical career as to the requirement of clarity. In his dissertation, Hartshorne justifies the inescapable obscurity of metaphysical statements. William Lad Sessions, who summarized and analyzed Hartshorne’s doctoral work writes: "The concepts, or ‘ideas’ of philosophy, Hartshorne insists, are communicable (or ‘transferable’ to use his term which points to the experiential basis of conception) but only partially so, because . . . obscurity is directly proportional to concreteness, and good philosophy plunges thought into the concrete. . . . Hartshorne therefore is willing to admit that he may be understood only by other Idealists or even only by himself" (HEP 17). It is obvious that Hartshorne later rejected this very peculiar view, probably under the influence of Peirce’s philosophy as well as neopositivistic and analytical standards. Discovering obscurities in other philosophical systems came to be one of his favorite activities.
Hartshorne’s program seems to presuppose also that the "backbone" of metaphysics is neutral to the "flesh" (content) of reality, so that when we say coherence or consistency, these words mean, or should mean, the same for different philosophers.2 It is true that some metaphilosophical principles are almost universally accepted (e.g. noncontradiction), but others are strictly connected with given systems. Coherence may be a good example. In Whitehead’s interpretation coherence presupposes that "no entity can be conceived in complete abstraction from the system of the universe" (PR 3/5). The consequences of applying this requirement to any system may be very significant. It forbids, for example, arriving in metaphysics at the notion of a God that would not be the exemplification of metaphysical ideas. When Whitehead experimented with the notion of God as a timeless actual entity, this was, strictly speaking, an arbitrary disconnection of principles. The drive toward coherence, I believe, forced him (and later his followers) to reject that notion and to admit that God, as everything else, must be in time, and changeable.
Applied to the history of philosophy the principle of coherence shows incoherence in every nonholistic system. Certain methodological standards may then be connected so strictly with the content of a given system that some moderation should be exercised in using them to evaluate other philosophical positions. Seeking a philosophical justification of holism seems to be a much more fruitful strategy than finding incoherences in various philosophies.
I mentioned that there are some metaphilosophical criteria which are almost universally accepted. But even they, if applied properly, have a limited power in eliminating metaphysical alternatives. Let us take consistency as an example. In logic, a given system is consistent if within that system there are no contradictions. A given system is not inconsistent if some of its statements contradict the statement of a different system. Whitehead was very clear about this. In Adventures of Ideas he writes: "When a new working hypothesis is proposed, it must be criticized from its own point of view. For example, it is futile to object to the Newtonian dynamics that, on the Aristotelian system, the loose things on the earth’s surface must be left behind by the earth’s motion" (AI 223).
Hartshorne’s hope that two different and internally consistent metaphysical systems do not exist is illusory. In fact, there are many different and internally noncontradictory systems. And if some of them are inconsistent, they can be made consistent and will still be different. The main problem with the evaluation of various metaphysical theories lies in their principles and in their relation to reality (experience). Here, however, some empirical criteria are needed that Hartshorne’s metaphilosophy seems to be lacking.
But there is also another limitation for the argument from inconsistency, even it is applied to the statements of the same system. It would be absurd to try to reject Nicolas Cusanus’ idea of God as ‘coincidentia oppositorum’ because of the inconsistency of this idea. What Cusanus means is that God cannot be conceived in any consistent way. In short, the requirement of consistency cannot be applied to God.
A different Hartshornean rationalistic principle says that in the process of solving problems an exhaustive list of possible theoretical options should be prepared. In Creative Synthesis and Philosophic Method Hartshorne writes: "A basic procedure in all thinking is to exhaust possible solutions to a problem and arrive at the best or truest by elimination of those that are unsatisfactory. . . . Very often, what one needs are the three ideas of quantification all, some, and none. For example, it is fallacious to say that either God is finite or he is not finite. The real disjunction is, God is in all aspects finite, in no aspects finite, or in some aspects finite and in others not" (CSPM 84-5).
Many questions may be formulated in connection with this method. First, how can we be sure that all possible solutions are included on our list? Richard Martin, commenting on Hartshorne’s method writes: "No matter how one were to circumscribe a set of such [possible doctrines], someone might well come along with a doctrine just different enough not to fit" (PSV 142). Martin thinks that this doctrine "reads well in principle, but will rarely be helpful in practice, except in very simple cases’ (PSV 142). Let us assume, however, that exhaustion of all possible solutions in a given matter can be reached. How, then, can we choose between them? When is a given doctrine satisfactory?
Hartshorne applies various principles -- for example, the principle of contrast or the principle of a golden mean. Here, I would like to point out some problem connected with the principle of a golden mean. It says that we should exclude extreme positions and accept the moderate one.3 So, in Hartshorne’s example, we should choose the position "God is in some aspects finite and in some infinite." But what about a different set of possible doctrines? (1) Everything is material. (2) Everything is psychical. (3) Some things are psychical, some are material. Which position here is the moderate one: materialism, panpsychism, or dualism? If we would like to copy the previous solution we will answer: dualism. But for Hartshorne the correct solution is panpsychism, and the extreme ones are materialism and dualism.
It seems to me, then, that the rule of the golden mean in Hartshorne’s interpretation is no longer a rule, and that, if applied, his choices between various philosophical positions are made on some other basis. It is very likely that, at least in some cases, Hartshorne first takes a position on a given problem, and then he interprets the other solutions as extreme. If this is the case, moderation is not an effective metaphilosophical principle. But even if it were, I don’t think that in all cases it would be desirable to apply it, unless somebody wanted lobe an eclectic (PSV 142).
Another of Hartshorne’s metaphilosophical notions (or principles) -- conceivability -- is more complicated than those previously discussed. According to Hartshorne, there are certain words (often used in philosophy) which do not have any referents in experience (or reality). These words should be abandoned in philosophy. "Neither Aquinas nor anyone else," he writes, "has ever had any idea of ‘pure actuality’. . . . Neither Descartes nor anyone else has really known what could be meant by nonextended, mental substance.’ Neither Spinoza nor anyone else had a definite, consistent idea of non-contingent modifications of substance . . . . The history of metaphysics is indeed in considerable part a story of failures to use words significantly and coherently" (CSPM 70).
The term "conceivability" appears in Hartshorne’s definition of metaphysics as "the study which evaluates a priori statements about existence. A priori is here used in a somewhat Popperian sense of contradicting no conceivable observation" (CSPM 19). What does "conceivable" mean here? I take it to mean possible observations or possible states of affairs. Something which is not conceivable is also not possible.4 But what is, and what is not possible, and why? Traditionally (since Leibniz) the realm of possibilities was divided into two classes. More narrowly, real possibility is limited by the law of noncontradiction and by laws of nature. Broadly speaking, logical possibility is restricted only by the law of noncontradiction.
Having, however, only these two criteria, it is sometimes very difficult to evaluate if given ideas are possible or not. The idea of a man jumping over the moon seems to be logically possible but it is forbidden by actual laws of nature, so it is really impossible. But maybe laws of nature can change, so that the idea is, in fact, also really possible. More serious problems, however, concern logical possibility. We may agree that some Simple ideas, like the idea of a square circle, are contradictory. But there is no agreement among philosophers when it comes to more complicated ideas. The idea of creatio ex nihilo, or nontemporality, is regarded as noncontradictory by some, and absurd by others. It means that noncontradiction is not the only criterion of logical possibility. After all, it is only a formal feature. But there is probably no objective content-criterion for logical possibilities. Every such criterion would involve premises belonging to particular philosophical systems.
Hartshorne wants to overcome the dualism of logical and real possibility. In the article entitled "Real Possibility" he writes: "[It] is only because of lack of clarity or definiteness that really impossible descriptions appear to us as logically possible. If we had perfect command of our ideas we should see logical absurdity in any description that is really impossible" (RP 594). This, however, doesn’t provide us with an effective criterion to evaluate if a certain idea is possible or not. We are not ideal cognitive subjects. Hartshorne suggests an additional criterion. "My proposal," he writes, "simple and all-too-simple as it may sound, is then this: nothing has even a logically possible alternative unless it once was future" (RP 596). This means (among other things) that time is a limitation for possibilities.
We still don’t know if it is possible for a man to jump over the moon, but we may now eliminate many other ideas as impossible. And so the idea of timeless truth is absurd. God has to be temporal and changeable, and the idea of a timeless God is impossible. So the consequences of the application of this criterion are quite significant. We may, however, ask if such a temporalistic criterion can be imposed on the realm of possibilities.
I have some doubts concerning Hartshorne’s hypothesis. They have their source in the history of science. If we look at the adventure of human ideas we notice that our thoughts have been developing from narrower to broader concepts of possibility. This adventure may even be described as a battle with the limits of possibility. In medieval philosophical texts one idea often given as an example of impossibility was the "rose in the winter." For people at that time this was a clear contradiction. It seemed to be an obvious and necessary truth that through a point not belonging to a straight line it is possible to draw one and only one line parallel to the given line. But it was later proved noncontradictory (and so also possible) to say that through that point we can draw no line parallel to the given one. Time was regarded as absolute, but in relativity theory it is conceived as relative. The history of ideas warns us to be very cautious in limiting possibilities. The attempt to restrict the realm of possibility by some simple hypothesis is probably connected with a certain element, deeply rooted in our human nature, which could be called "the quest for conceivability" and which is a version of the quest for cognitive security.
I am afraid that in theology this quest may lead to various distortions of the reality this discipline discusses. Almost every idea of God offered by philosophers and theologians was an exception to the respective philosophical systems and not their primary exemplification -- here I agree with Hartshorne. But instead of rejecting these historical concepts of God I would say that there is a valid intuition in them -- namely, that God is ultimately incomprehensible in any clear and consistent manner. If this is true, then the project to conceive God, to comprehend Him fully, will inevitably lead to distortions. They will most often go in the direction of anthropomorphization.
In Hartshorne’s case, if we are in time, then God must be in time, too; "if we could not observe the actualization of the alleged possibility ‘there might have been nothing,’ no more could God observe it. . . . Also, if we could not observe the non-existence of God,’ neither obviously could God observe it" (CSPM 21). 1 myself do not see why I should insist that I be able to clearly conceive the ultimate reality, when I cannot conceive clearly many theories describing finite reality. Besides, the limits of our conceivability are not stable. Scientists who invent new theories usually reject certain epistemological presuppositions which were once regarded as absolute axioms. If I were forced to choose between God as temporal and God as pure act (or as a timeless singular actual entity). I would choose the latter. And my reason would be exactly the same as the reason Hartshorne gives for rejecting it, namely that this God is more inconceivable.
Hartshorne often emphasizes that metaphysics is looking for a priori truths. He seems to use this notion interchangeably with the notions of unrestrictive, strictly universal, eternal, or unconditionally necessary truths (CSPM 24). Ideas, according to Hartshorne, come from experience: "No experience -- no ideas" (CSPM 31). But there are two ways of acquiring these ideas from experience: "the ordinary concepts. . .derive from special kinds of experience, and get their essential meaning from this specialization. . . . [T]he metaphysical concepts derive from any experience, even unreflective" (CSPM 31). In other words, metaphysical truths must be exemplified in every experience.
Whitehead called this feature "adequacy." A metaphysical scheme is adequate, according to him, when "the texture of observed experience, as illustrating the philosophic scheme, is such that all related experience must exhibit the same texture" (PR 4/5). Hartshorne’s rationalist-sounding notion of apriority is, then, parallel to the notion of adequacy, which in the Whiteheadian scheme expresses the empirical side of philosophy. There are, however, some differences. Whitehead ascribes the requirement of adequacy to the whole system of ideas, and Hartshorne speaks rather about a priori truths (or statements). Besides, adequacy (and also necessity) is, for Whitehead, a feature of an ideal system -- philosophy is only "the endeavor to frame" such a system. Hartshorne seems to believe that a priori and necessary statements can be formulated so that apriority (and necessity) is not an eschatological ideal. It seems tome that in both cases the Whiteheadian position is more consistent. Statements which Hartshorne regards as necessary truths draw their meaning from his whole system. The claim that "necessarily, creative experience occurs" presupposes as necessary all the statements which describe what creative synthesis is.
It is, then, more consequent to say that adequacy concerns whole system of ideas, rather than particular metaphysical statements. Besides, since the set of experiences changes (e.g. because of new scientific theories), and because it is difficult to check if, in fact, every experience confirms a given truth (system), it is better to say that adequacy and necessity (or apriority) are ideals. This intuition is present from the beginnings of philosophy. The very term "philosophy" means "the love of wisdom," and not "the wisdom." The last one, Greek thinkers believed, is a privilege of the gods. We, humans, can only be lovers of wisdom.
Putting aside the differences between Whitehead and Hartshorne, one thing is clear: that Hartshorne’s notion of apriority allows for an appeal to experience as a test of metaphysical statements. This means that a certain metaphysical theory is evaluated not only with regard to its internal intelligibility (as Hartshorne claimed in his program), but also in the aspect of its agreement with experiences. This, however, raises problems from which extreme rationalism was to be the escape. If every experience is already interpreted (as both Hartshorne and Whitehead believe), then the philosopher may choose to say, for example, that change is a fact (given in experience), but personal identity is an interpretation of simpler, more basic, or less interpreted, facts. The genuine test of adequacy (apriority) is impossible in this case. Everything which can confirm a given system may be regarded as a fact, while everything which could falsify it may be treated as already an interpretation. In his conception of experience Hartshorne includes nonsensory and nonhuman experiences, in which case the whole test of apriority becomes even more complicated.
If my observations are true, then the main aim of Hartshornean (and also Whiteheadian) metaphysics is not so much a search for truths about reality, as a redefinition of our basic notions of fact, truth, experience, and reality. A given philosophical statement will be a priori, or necessary, with regard to axioms, postulates, definitions and rules of inference of this system. But, given this conception of experience, there is no direct or indirect way to evaluate the definitions, postulates and axioms. It cannot be done directly, by comparing reality or experience with a given postulate or definition, because it is assumed that every experience is interpreted. It cannot be done indirectly, either -- by comparing the consequences of a metaphysical system with experience or reality -- because this would be only the comparison of meaning postulates with theses of the system. And the test of conformity between metaphysical theses and postulated meanings of experience or reality is only a test of consistency and not of apriority or adequacy.
Charles Hartshorne is, without any doubt, one of the greatest metaphysicians of the 20th century. In this paper I have concentrated on only a few elements of his metaphilosophy, which seemed to me problematic. Hartshorne’s program for philosophy is based on his conviction that "logical structure [constitutes] the basic difference between systems," and that "metaphysical error is exclusively a matter of confusion, inconsistency or lack of definite meaning, rather than of factual mistakes" (CSPM xiv, 69). He offers a set of general rationalistic principles (of which I discussed only a few), which, if carefully applied, will lead us, as he believes, to truth. This conception of metaphysics was created, I believe, under the influence of his encounters with minimalistic philosophies, especially with neopositivism.
I have attempted to show that Hartshorne overestimates the argumentative power of his rationalistic principles in the process of eliminating other philosophical positions, and that genuine empirical criteria are inevitable if metaphysics is going to be something more than pure speculation. There is, in fact, an empirical side to Hartshorne’s philosophy (similar to Whitehead’s) but it is hidden in the rationalist-sounding word a priori. I argue, however, that on the basis of Hartshorne’s conception of experience as always being interpreted, a genuine test of apriority (adequacy) is not possible.
References
CHPP -- David R. Griffin. "Charles Hartshorne’s Postmodern Philosophy." Hartshorne, Process Philosophy and Theology. Ed. Robert Kline and Stephen Philips. Albany: State University of New York Press, 1989.
CSPM -- Charles Hartshorne. Creative Synthesis and Philosophic Method. La Salle, Ill: Open Court, 1970.
HEP -- William Lad Sessions. "Hartshorne’s Early Philosophy." Two Process Philosophers: Hartshorne ‘s Encounter with Whitehead. Ed. Lewis S. Ford. Atlanta: Scholar’s Press, 1973.
PB -- George Wolf. "The Place of the Brain in the Ocean of Feelings." Existence and Actuality. Ed. John B. Cobb, Jr. and Franklin I. Gamwell. Chicago: University of Chicago Press, 1984.
PSV -- Richard Martin. Primordiality, Science, and Value. Albany: State University of New York Press, 1980.
RP -- Charles Hartshorne. "Real Possibility." The Journal of Philosophy 60/21 (October 10, 1963): 593-605.
RPM -- Charles Hartshorne. "The Rationalistic Principle in Metaphysics." Philosophy and Phenomenological Research 8/3 (March 1948).
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