At the end of the 19^th century, the European philosophical turf was shared by two factions, both coalitions, those of an idealistic strain, largely Hegelians, on one side, and those of a materialist or skeptical bent, indebted to British empiricism and the Critiques of Kant, on the other. Long eclipsed was the metaphysics of Aristotle and the Schoolmen.

Henri Bergson in an attempt to confront the mechanistic and deterministic philosophies of his day, philosophies often presented by their advocates as the rational foundation of modern science, developed a metaphysics of being critical of both Hegel and the empiricists. One of his most promising disciples was the young Jacques Maritain who had turned to Bergson then lecturing at the Collège de France because of a similar discontent with the prevailing intellectual milieu. Maritain, although initially attracted to the philosophy of Bergson, soon became critical of his mentor because in his judgment Bergson's metaphysics remained linked to and dependent upon the science of phenomena it hoped to replace. Never achieving metaphysics in the Aristotelian sense of the term,⁽¹⁾ it remained in Maritain's judgment a process philosophy, not a philosophy of being. Maritain's subsequent reading of Aristotle led him under the influence of Ernest Psichari to Thomas Aquinas. He was to say later that he was already a Thomist before he read a word of St. Thomas.

Maritain was not alone in the search for a way out of the prevailing philosophical climate. In reaction to German idealism, which itself was framed as a reaction to Kant's Critiques, new and critical realisms were beginning to emerge on both sides of the Atlantic. Hegel, initially embraced as an antidote to empiricism, was abandoned when it became clear that Hegelians were hard pressed to account for the march of new scientific techniques which were leading to remarkable discoveries in the natural sciences. Above all, Maritain was confronted with August Comte's positivism. Schooled in the British empiricism of the day, Comte not only ruled out metaphysics but ruled out theoretical physics as well and both for the same reason, a denial of the efficacy of causal reasoning. According to Comte, physics errs as does metaphysics when it postulates abstract entities as explanatory causes. The success of 19^th and 20^th century theoretical physics had yet to undermine positivism as a philosophy of science. Quite apart from its speculative implication, Comte recognized the social implications of the empiricism emanating from the British Isles, implications which led directly to a secular humanism which he codified in his "religion of humanity."

Generally accorded the title, "Father of Positivism," Comte is also regarded as one of the progenitors of sociology. Although Comte's interests led him away from the philosophy of science per se and into the field of sociology, the term he coined came to be used in the wider sense of a philosophy of knowledge which limited knowledge to sensory experience. Hence Maritain's attempt to counter the "brutal empiricism and nominalist pseudo-rationalism" by showing that knowledge is not limited to the descriptive sciences, that ancient truths about nature, human nature and cognitive ability remained viable and, indeed, vital to humanity. Maritain is later to press the point in a work published under the title, Ransoming the Time.⁽²⁾

Reflections on the nature and capacity of human knowledge date to the pre-Socratics. Plato's discussion of science and the claims to knowledge by the Greeks, as Maritain recognized, will forever remain a starting point for the philosophy of science. It was Plato who bequeathed to Western philosophy the insight that all science is of the universal. Aristotle concurred, but he found the universal not in some realm of archetypes but in the nature common to members of the species. Aristotle taught that by a process of abstraction we come to know the essence, quiddity, or nature of a thing, prescinding from its accidental features which it may or may not have while remaining the thing that it is. Such is the object of science, the nature of an entity, the structure of a process, its properties and potentialities. Yet to have scientific knowledge is not simply to know what is, not simply to have uncovered a law of nature. For Aristotle to have scientific knowledge is to know the entity, process, or property in the light of its cause or causes. Presupposed by Aristotle are two principles, the principle of causality and the principle of substance, both principles rejected by the British empiricists.

The positivism which Maritain confronted denies at once the intelligibility of nature and the power of intellect to grasp "the more" that is given in the sense report. Maritain offers an elaborate defense of the first principles of thought and being in his Existence and the Existent, affirming that there is more in the sense report than the senses themselves are formally able to appreciate.⁽³⁾ John Locke, in denying the reality of substance, reduces what we call substances to a "constellations of events" or sense reports. According to Locke, we use terms which imply substances, but this usage is merely a shorthand way of pointing to something without repeating at length the properties we associate with that something or constellation. Ockham revisited.

David Hume's account of causality similarly limits knowledge to a simple sense report. We experience succession, Hume tells us, not causality. "Cause" is the name we give to the antecedent, contiguous in place, continuous in time, and habitually associated with the consequent which we designate "effect."

If there are no natures or substances independent of the mind's creating them, if there is no causality, the enterprise of metaphysics collapses. For after all, metaphysics is based on the assumption that the realm of being is greater or wider in designation than the being reported by the senses. If the material order reported by the senses is all there is, then the most general science of reality is natural philosophy or the philosophy of nature. If there is an immaterial order of being as well as the material world of sense, then the most general science or reality is the philosophy of being, also known as metaphysics or ontology. One can conclude to or reach the immaterial order only by a process of reasoning. Such reasoning has led mankind through the ages to affirm the existence of God, to posit an immaterial component of human knowing and a spiritual or immaterial soul.

It is to be noted that the same sort of reasoning that leads one to affirm the existence of God also leads one to affirm the existence of the submicroscopic. As Comte himself recognized, causal reasoning is common to both natural theology and theoretical physics. The efficacy of causal reasoning is dramatically seen in those sciences where the postulated entities of one generation become the encountered ones of another. It can be shown that limiting knowledge to the sense report has implications not only for the natural sciences but for law, the social sciences, and theology as well. On a strict positivist account, science, in effect, is reduced to description and prediction, the social sciences are denied their object, "human nature," and of course natural theology is denied its object since there is no way to reason to the existence of God.

Maritain first takes as his task in developing a philosophy of science to be the defense of the first principles of thought and being. Put simply, things exist apart from a knowing mind (intelligibility); things are what they are (identity); a thing cannot be and not be at the same time and in the same respect (non-contradiction); a thing is either intelligible in terms of itself or in terms of another (efficient causality or sufficient reason); every agent acts on account of a preconceived end, or, put another way, being in act is intelligible (final causality). These principles are so fundamental that there are none prior to them by which they may be demonstrated. They are the principles upon which all demonstration depends, principles which though they cannot be demonstrated can be defended. Maritain's entire philosophy of science may be regarded as their defense against Locke, Hume, and certain misleading misinterpretations of relativity theory and quantum mechanics.

He next focuses his attention on the abstracting intellect and the degrees of abstraction which make possible the various sciences from physics to metaphysics. In these discussions he displays his indebtedness to Aristotle and Aquinas as well as to the Thomistic interpreters, Cajetan and John of St. Thomas.

Quite apart from his subscription to an Aristotelian-Thomistic theory of knowledge, Maritain was aware that the British empiricists as well as Comte failed to pay much attention to actual practice in the sciences. Maritain begins a chapter of a major work, The Degrees of Knowledge, entitled "Philosophy and Experimental Science," by quoting Émile Meyerson, "True science, the only one that we know, is in no way, and in none of its parts in accord with the positivist scheme."⁽⁴⁾ The empiricists notwithstanding, reasoning on a causal basis from the observed to the unobserved is in common practice in the natural sciences. The existence of bacteria was inferred long before the microscope displayed their reality. In physics and chemistry molecular structures were similarly inferred long before electron microscopes and particle accelerators graphically confirmed their reality. It is not misleading to say that in physics causal explanation is taken for granted. The encountered is routinely explained by the nonencountered. No one who looks at the course of nineteenth and twentieth-century theoretical physics can affirm that science is simply description and prediction.

Maritain had not only studied biology in Heidelberg but was conversant with the work of Max Planck, Albert Einstein, Louis de Broglie, Schrödinger, and Werner Heisenberg, to name only a few. He attached particular importance to quantum mechanics and relativity theory because they call into question the validity of certain common-sense conceptions of space and time.

Scientific knowledge, Maritain writes, is knowledge, in which, under the compulsion of evidence, the mind points out the reasons why things are the way they are and not otherwise.⁽⁵⁾ Science deals with things, but not the flux of the singular. It lays hold of what things are by means of a process of abstraction, discovering their intelligible nature--a universal nature, not the contingent of the singular. "The contingencies of the singular escape science. The necessities of the universal are the proper objects of its grasp."⁽⁶⁾ He continues, "The universality of the object of knowledge is the condition of its necessity, the very condition of perfect knowledge or science."⁽⁷⁾ The sciences of explanation "set before the mind intelligibles freed from the concrete existence that cloaks them . . . essences delivered from existence in time."⁽⁸⁾

Maritain can quote Aristotle and Aquinas in support of his position. This is the first stage of his attempt to show that metaphysics, indeed science, is possible by pointing to the mind's ability to abstract from the singular to capture the universal or intelligible, common nature of many, to see the many as a class. This abstractive power enables us to identify "laws of nature" and is the basis of all taxonomy. Maritain, again following Thomas, calls this the first degree of abstraction. The second degree is mathematical abstraction, the kind of abstraction involved when the mind not only leaves behind the singular but also the defining characteristics of a class to focus only on the entity as a unit or as something possessing extension or a certain configuration. Thus, arithmetic and geometry and their derivative sciences come into being. We can speak of "five" or "six," leaving behind the fact that we may be talking about bells, books, or candles. Similar we can talk about the properties of circles, spheres, cones, and straight lines even though none exists as such in reality. Obviously there are circular, spherical, and conical objects in reality, but none is a perfect exemplar of the idealized abstraction.

Maritain discusses at length the so-called intermediate sciences, the physico-mathematical sciences. "Physico-mathematical science," he writes, is not formally a physical science. Although it is physical as regards the matter in which it verifies its judgments, and although it is oriented towards physical reality and physical causes as the terminus of its investigations, physico-mathematical science does not, however, aim to grasp the inner ontological nature itself."⁽⁹⁾ Beware of abstractions, he cautions.

Discussing the nature of quantity, extension, and number, he notes, "The enormous progress made by modern mathematics has rendered more indispensable than ever before the philosophical study of the first principles of mathematical science, which alone can provide a rational account of the true nature of mathematical abstraction and the mental objects which it considers, the properties and mutual relationships of the continuous and discontinuous, the real meaning of surds and transfinite numbers, the infinitesimal, non-Euclidian space, etc. and finally the validity of mathematical transcripts of physical reality, and of such hypotheses, for example, as the theory of relativity."⁽¹⁰⁾

It is at the third degree of abstraction that the object of metaphysics is attained. At that level the intellect prescinds from every feature, physical and quantitative, to focus on what the whole of reality has in common, namely, being. At this level "the mind can consider objects abstracted from and purified of all matter. In this case it considers in things only their very being with which they are saturated, being as such and its laws. These are objects of thought which not only can be conceived without matter, but which can even exist without it."⁽¹¹⁾

Returning to his discussion of natural science, there are two possible ways, he says, of interpreting the conceptions of modern physics. "The one transports them literally, just as they are, on the philosophical plane, and thereby throws the mind into a zone of metaphysical confusion. The other discerns their spirit and their noetic value in an effort to determine their proper import."⁽¹²⁾

One may ask, is real space, Euclidean or non-Euclidean? Is the space postulated by the Einsteinian theory of gravitation real or not? The student of modern physics, Maritain responds, must beware of equivocations. The world "real" has not the same meaning for the philosopher, for the mathematician, and for the physicist. For the mathematician, a space is "real" when it is capable of mathematical existence, that is to say, when it implies no internal contradiction and duly corresponds to the mathematical notion of space, that is, duly constitutes a system of objects of thought verifying the axioms of geometry.⁽¹³⁾

For the physicist, space is real when the geometry to which it corresponds permits the construction of a physico-mathematical universe in which all our pointer-readings are "explained" and which at the same time symbolizes physical phenomena in a coherent and complete fashion. For a long time Euclidean space sufficed for the interpretations of physics, but today to interpret the measurements it gathers from nature within which geometry and physics are as far as possible amalgamated, it is necessary to have recourse to spherical and elliptical spaces. For us, it is a question of knowing what is real space in the philosophical sense of the word, that is, what is "real" as opposed to an "entity of reason."

Euclidean, Riemannian, and other geometrical entities are "translatable" from one system to another, and all these geometries are equally "true," but they cannot be equally real in the philosophical sense of the word. Mathematical intelligibility by itself alone tells us nothing. The straight line of an elliptical plane and the figure which corresponds to it in a Euclidean model are not different expressions of the same thing. "They are intrinsically different entities, belonging to intrinsically different worlds, and from one of these worlds to the other they correspond analogically. To affirm the reality of one space is not to affirm at the same time the reality of all the others, but their unreality."⁽¹⁴⁾ Nor will the verification of our senses and of our measuring instruments tell us anything about their reality since with them we quit the mathematical order for the physical order. The mathematical model may serve as a "nucleus of condensation," a model which enables us to correct and interpret the ensemble of measurements taken.

Euclidean space is directly constructible in intuition. Others of necessity are referable to the Euclidean notion of space for their intelligibility. All attempts that have been made to obtain an intuitive representation of non-Euclidean geometries, by Einstein, for example, show that these geometries can be rendered imaginable only by reduction to Euclidean geometry. "The model of the thermic universe invented by Poincaré, in which we would be born with the geometry of Lobatchevsky, and that sequence of very simplified sensations that Jean Ncod has thought up and which would give a fictitious subject the idea of the most diverse geometries, confirm by a sort of counter-proof this privilege of Euclidean space."⁽¹⁵⁾ In sum, non-Euclidean geometries presuppose notions of Euclidean geometry. They offer analogical concepts with Euclidean concepts providing the primary analogate. In spite of the use that astronomy makes of them, non-Euclidean space is a being of reason. "It is Euclidean space which appears to the philosopher to be an ens geometricum reale."⁽¹⁶⁾ This real geometric space is finite, that is to say, actually existing space is coextensive with the amplitude of the world. Infinite geometric space is a being of reason.

Speaking of the atom presented by the "new physics," Maritain says that physicists tend to form a pure abstract mathematical equivalent of a given atomic structure, which thereby becomes unrepresentable to the imagination and at the same time becomes divested of any ontological meaning. "The equivalent tends to become a more and more fictitious and more and more perfect symbol of the real nature, unknown in itself, of that existing something as other to which determinately corresponds the name atom. Thus, it knows this nature more and more profoundly, yet more and more enigmatically, and metaphorically, to put it bluntly, in the measure that it constructs the myth-a being in reason founded in re- which takes its place."⁽¹⁷⁾

Maritain then turns to the epistemological conditions and characteristics of a philosophy of nature which undergirds empiriological knowledge in general. He quotes Sir Arthur Eddington who writes that the physicist of today knows "'that our knowledge of objects treated in physics consists solely in readings of pointer and other indicators' and who knows likewise that 'this schedule of pointer readings' is attached to some unknown background.'"⁽¹⁸⁾

Like Eddington, Maritain is insistent that a mathematical reading of sensible phenomena cannot speak the last word about the physical real. Physico-mathematical knowledge is not to be mistaken for an undergirding philosophical account of nature. We cannot ask a physico-mathematical approach to give an ontological explanation of the sensible real, let alone an account of human thought and volition. True, the human mind inevitably tends toward a mechanistic philosophy and endeavors to explain everything in terms of extension and movement. "It was bound inevitably," Maritain writes," to endeavor to make ontological reality intelligible in terms of extension and movement."⁽¹⁹⁾ A Cartesian legacy resurfacing, Maritain might say.

Given that the natural sciences aim at giving a mathematical interpretation of sensible nature, it is easy to conclude, as do many of our contemporaries, that science is capable of explaining the whole ontological reality by extension and movement. But it has yet to do so! "Well, if science cannot do so right away, it will be able later on," is a common refrain when asked for the evidence. The spiritual dimension of man remains elusive, yet the twenty-first century disciples of Hume remain confident that the genome project will eventually disclose all. Maritain's life work can be read as a rebuttal of contemporary claims that complex organic forms and the spiritual component of human nature are the result of material forces combining with random mutations, the result of necessity and chance, with no creative intelligence behind them. Cultural shifts, if not an outright hedonism, obviously flow from this line of reasoning.

To follow Maritain's every line of argument would require a volume in itself. Throughout his long career and extensive publication he has defended a realism which is not satisfied with a purely empirical or phenomenal account of what is. In the latter half of the 20^th century that realism has gained notable adherents. To mention only two: William A. Wallace, principally in his Modeling of Nature,⁽²⁰⁾ has carried the Aristotelian-Thomistic analysis into yet another generation; and Rom Harré, in the Principles of Scientific Thinking has shown the necessity of recognizing a nature or structure beyond the empirically given, one that is responsible for measurable traits and is conceptually present to the mind by means of an iconic or sentential model.⁽²¹⁾ While Harré remains a materialist, he is not satisfied with the reduction of science to description and prediction, which he believes fails to recognize its explanatory character. Others outside the Aristotelian tradition have come to the similar conclusion regarding the nature of scientific inquiry. Yet the recognition of an immaterial order, attainable through reasoned enquiry is far from accepted in today's academic climate, and for the reasons Maritain gives, the failure to acknowledge, put simply, that more is given in the sense report of reality than the senses are able to appreciate.

1. Jacques Maritain, Redeeming the Time, London: Geoffrey Bles, 1943, p. 47.

2. Jacques Maritain, Ransoming the Time, New York, Scribner's Sons, 1941; also published in England as Redeeming the Time, London, Geoffrey Bles, 1943.

3. Jacques Maritain, Existence and the Existent, trans. by L. Galantière and G. Phelan from Court Traité de l'existence et de l'existent, New York, Pantheon Books, 1948.

4. Jacques Maritain, "Philosophy and Experimental Science," in The Degrees of Knowledge (Les Degrès Du Savoir) trans. from the 4^th French ed. By Gerald Phelan (New York: Scribner's, 1959), p. 21. The English-language translation employed is the one cited here.

5. Ibid., p. 23.

6. Ibid., p. 27.

7. Ibid.

8. Ibid., p. 33.

9. Ibid., p. 61.

10. Ibid., p. 164.

11. Ibid., p. 36.

12. Ibid., p. 171

13. Ibid., pp. 165-67.

14. Ibid., p.167.

15. Ibid., p. 168.

16. Ibid., p. 169.

17. Ibid., p. 173.

18. Ibid., pp. 173-74.

19. Ibid., p. 42.

20. William A. Wallace, The Modeling of Nature: Philosophy of Science and Philosophy of Nature in Synthesis (Washington, DC: The Catholic University of America Press, 1996.)

21. Rom Harré, Principles of Scientific Explanation (Chicago: University of Chicago Press, 1970).