Introduction to the Philosophy Xavier Zubiri


The creation of a new philosophical system is a staggeringly difficult task, fraught with myriad dangers, pitfalls, and problems.  Only one of supreme genius can undertake this enterprise with any expectation of success, and then only when old ways of thought have shown themselves inadequate to cope with the march of human knowledge.  It is fortunate that these conditions have been fulfilled in our day and in the person of Xavier Zubiri (1898-1983).  No one can say now if this or any future philosophical system will be the definitive one; but Zubiri’s effort is surely the grandest, most boldly and most radically conceived effort to integrate the Western (and to a considerable extent, Eastern) philosophical tradition, the explosive growth of scientific knowledge, and the rich artistic, literary, and cultural traditions of European and world civilization. 

Of course the history of philosophy is littered with corpses of failed systems.  Many are the philosophers who, contemplating this situation, saw in it nothing but an inconvenient fact arising from some fault in the assumptions, reasoning, or scope of their predecessors’ work.  Each expected to put paid to this situation once and for all with his own new and improved philosophy, only to see it fall to the same fate.1  Zubiri is determined to avoid such a fate, and to accomplish that goal, he needs to do three things:

  • Determine what went wrong with all past philosophies, not individually but in common.  To do this he must penetrate to a much deeper level than any of these philosophies, and determine the unspoken and unrecognized assumptions that lie there.
  • Develop a new way of doing philosophy not subject to the vicissitudes of history and changes in the scientific worldview.  This will require a totally new conception of reality as something open at multiple levels, rather than closed, fixed, and exhaustible, and a corresponding new theory of intelligence, knowledge, and truth.
  • Demonstrate that there is genuine progress in philosophy by creating a new synthesis which is not a drop-in replacement for and rejection of all the old erroneous systems, but rather something which absorbs their key insights and refines and/or corrects them in a dynamic, rather than a static synthesis such as that of Kant.  This synthesis must be equally capable of absorbing new developments in science and mathematics.

It is important to understand at the outset just how radical Zubiri’s rethinking of philosophy had to be in order to achieve his goal.  Though in constant dialogue with the history of philosophy, and recognizing that this history must be the starting point for his (or any effort), Zubiri:

  • Rejects the traditional view of reality as a zone of things, whether “out there” beyond perception, within the mind, in the realm of ideas, or anywhere else, replacing it with a more fundamental and general notion, that of formality, which refers to the nature of what is present to the intelligence.
  • Rejects the traditional four-part division of philosophy into metaphysics, epistemology, logic, and ethics as the primary basis for its organization, instead recognizing that no such strict division has ever been achieved or is even possible, and that a new approach to human intellection is necessary, which underlies any such division.
  • Rejects the traditional notion of God as a reality object, instead conceiving of Him as a reality fundament or ground, thus radically changing the foundation of theology, which is no longer based on rational “proofs” of God’s existence, such as those of St. Thomas.
  • Rejects the traditional idea of reality as “closed” and static, as implied in most conceptions of essence, in favor of a new view of reality and essence as “open”;
  • Rejects the traditional notion of a person as another type of  “thing,” arguing that personhood is a separate, distinct kind of reality.
  • Rejects the traditional notion of sensible intelligence founded on opposition between sensing and intelligence, replacing it with a fully integrated conception, sentient intelligence.
  • Rejects the agreement of thought and things as the fundamental notion of truth; rather this dual truth is grounded on and subsequent to a more fundamental truth, real truth, the impressive actuality of the real in sentient intellection.

The first major work of his grand synthesis was Sobre la esencia (1963; English edition On Essence, 1980).   It dealt primarily with the object of knowing.  Zubiri’s main work, Inteligencia sentiente (1983; English edition Sentient Intelligence, 1999) deals primarily with the process of knowing, which is founded upon an analysis of intelligence.  These two subjects—object and process of knowing—should not be identified with “metaphysics” and “epistemology”, respectively, for two reasons: (1) the latter two topics are subsequent to and of more restricted scope than the problems Zubiri addresses; and (2) Zubiri explicitly rejects the modern notion that the problems of object of knowing and process of knowing can be or indeed ever have been rigorously separated, as the distinction between epistemology and metaphysics in post-Kantian thought generally suggests.2   The object and process of knowing are completely intertwined, and any comprehensive philosophy must address and encompass both together in its vision.  At the outset, this requires an analysis of intelligence—something which must logically precede any type of rigorous epistemology or Kantian critique.  As Robert Caponigri, translator of Sobre la esencia put it,

The theory of “sentient intelligence” must be distinguished from the “epistemological question” or the theory of knowledge.  The theory of intelligence is logically antecedent to the epistemological question and every epistemological theory eventually reveals that it presupposes a theory of the intelligence in its account of what and how man can know.3

Only when this foundation has been laid can work on a comprehensive epistemology be completed and securely grounded. Zubiri frequently criticizes previous philosophers for confusing epistemology and the theory of intelligence, and consequently advocating erroneous and often absurd theories.  He also believes that understanding this distinction is the key to unraveling some of the paradoxes and puzzles from the history of philosophy, many of which turn out to be pseudo-problems, such as Hume’s famous analysis of causality.  Finally, this analysis of intelligence undergirds Zubiri’s analysis of truth and the stages of intellective knowledge.

The purpose of this introduction is to orient the English-speaking reader with respect to Zubiri’s intellectual heritage, his point of departure, his goals, the organization of the work, the main currents of thought in it, and the innovations which Zubiri brings to the subject.  This is not to suggest that his work can be pigeonholed in any academic sense.  Zubiri was deeply and passionately committed to the intellectual quest for truth; and the seriousness and dispassionateness with which he viewed this quest is manifest on every page of his writing—the same seriousness which is so evident in Aristotle and the major philosophers in the Aristotelian tradition: Avero�s, Avicenna, St. Thomas, and Suarez.  To further this goal, Zubiri always seeks as Olympian a perspective as possible, encompassing all relevant knowledge when discussing any subject.  The result, in terms of scope, profundity, and originality, speaks for itself.

Life and Times

Xavier Zubiri y Apalategui was born in San Sebasti�n, on December 4, 1898. After preparatory studies in Guip�zcoa he attended the University of Madrid where some of his mentors were Angel Amor Ruibal, Garc�a Morente, Juan Zarag�eta, Jos� Ortega y Gasset, Julio Rey-Pastor, and Julio Palacios. He also included periods of residence at the University of Louvain, then under Cardinal Mercier, and the Gregorian University at Rome, the successor of the Collegio Romano. At the Gregorian, in 1920, he received the doctorate in theology.  In 1921 he received a doctorate in philosophy from the University of Madrid.  He refers to the period 1921-1928, when he worked extensively on phenomenology, as the “phenomenological-objectivist” epoch.

In 1926 he won the competition for the chair of history of philosophy at the University of Madrid. Between 1928 and 1931 he included trips throughout Europe to study under the masters of various disciplines: classical philology with Werner Jaeger; philosophy with Husserl and Heidegger; theoretical physics with De Broglie and Schr�dinger; biology with von Geluchten, Spemann, and Goldschmidt; mathematics with Rey-Pastor, La Vall�e-Poussin, and Zermelo.  As a result of these extended study trips, and his continual rethinking of philosophical problems, he embarked upon a second epoch, what he terms the “ontological” epoch (1931-1944), in which philosophical problems were radicalized, and he developed the concept of relegation, which became a cornerstone of his theological writings.  Zubiri’s Madrid University lectures, Metaphysics of Aristotle (1931-1932) and Pre-Socratics (1933-1934), acquired special resonance. During the course of the Spanish Civil War (1936 to 1939), he was in Paris teaching courses at the Institut Catholique and studying oriental languages with Deimel, Benveniste, Labat, Dhorme, and others at the Sorbonne. In 1939 he married Carmen Castro who had been one of his students, and was the daughter of the Spanish writer Am�rico Castro. From 1940 to 1942 he occupied the chair of history of philosophy at the University of Barcelona.

In 1943 Zubiri left the university to strike out on his own program of research and teaching in Madrid. This also marks the beginning of his final, mature period, the “metaphysical” epoch, whose main theme is reality.  He created his own model, the cursos (seminars), and through them he continued to present and involve others with his philosophical insights. His seminars were well attended, and he gathered a group of devoted followers with backgrounds in many disciplines who worked with him on the development of his thought. This group met weekly with Zubiri to discuss philosophical matters and review his texts as they were being written. The first major book of his mature period, On Essence, was published in 1963. It represents a complete rethinking of the concept of essence in light of the entire history of philosophy and the development of science during the 20th century. His principal systematic work, Sentient Intelligence, appeared in three volumes in the early 1980s. In this work, Zubiri builds upon the entire history of philosophy and science to create a new philosophical vision which incorporates key elements and insights from virtually all major thinkers, but which also shows how each of their systems went astray. The scope, depth, clarity, and profundity of Zubiri’s philosophy suggest that it is both the culmination of 2500 years of intensive intellectual struggle and the solid basis on which knowledge can build in the future. Zubiri died on September 21, 1983, in the midst of editing a new book for publication.

Key Elements in Zubiri’s Thought

Zubiri’s philosophical thought integrates twelve major elements:

    • The panorama of the entire Western philosophical tradition from the Presocratics through Heidegger, Logical Positivism, and to some extent, the 20th century English schools of thought.  Like Aristotle, Zubiri is constantly in dialogue with his predecessors.
    • Aristotle and the tradition of classical philosophy (though subject to relentless critical analysis and rethinking).  The gravity of Aristotle, as well as his encyclopedic vision and his understanding of the position of philosophy in the context of human knowledge, are particularly important in Zubiri’s thought.
    • Insights from the work of the Phenomenologists in the 20th century.  Though ultimately superseding them, Zubiri believes that there is a kernel of truth in their analysis of human experience which is essential to formulating a philosophy that takes account both of our undeniable perception of the world as real (see below), our understanding of it through science, and the limitations of our intelligence.
    • The overwhelming force of our direct perception of reality.  For Zubiri, this is the salient characteristic of human intelligence and must be the starting point for any firmly grounded theory of the intelligence, any epistemology, and ultimately any philosophy.  Though not specifically discussed by Zubiri, the tradition of the great Spanish mystics and the characteristics of their knowledge, in some ways akin to direct experience of the world, must have been in the back of his mind.4
    • Scientific knowledge, and especially the insight science has given us into the structure of the natural world and our ability to know that world.  Zubiri evinces a particularly keen interest in quantum mechanics and the revolution in physics which occurred in the early decades of this century.  His interest extends to all the sciences, and he believes that the cracking of the genetic code has provided insights into the biological realm which are in some ways analogous to those achieved in physics.
    • Modern logic and mathematics, especially G�del’s theorem, and the new insights about mathematical truths and mathematical realities these developments have yielded.
    • Nonscientific knowledge, specifically, the need to establish a foundation for it in a comprehensive philosophical system, and recognize its great and continuing contribution to the totality of knowledge. In what sense is a novel, a poem, or a painting about reality?  Why do we say that an artist has “perceived essential truths”?   Why does an artist create his works rather than just discourse about his subject?
    • The relation of God to the physical world and to science and scientific knowledge, especially physics; dealt with at length in earlier works,5 and the issue of the correct starting point for theology, with respect to “proofs” for God’s existence. 
    • The nature of causality and our ability to know it.  Zubiri believes that this issue is one of the most confused in the history of philosophy, and the root of many philosophical misunderstandings.
    • The fundamentally different reality of the person, as compared to ordinary physical realities.
    • Results and insights from philology, especially Indo-European philology. Zubiri believes that those who first created our language and our words had a freshness and clarity of vision with respect to certain basic human experiences that later generations could not replicate.6
    • The Christian theological tradition, with equal emphasis on Eastern (Greek) and Western Fathers and theologians.  Zubiri wrote extensively on this subject and related topics, including a trilogy published posthumously.


Zubiri integrates these twelve elements and extends them, as necessary, to create his new vision of knowledge and truth.  Naturally, the basic components of any

Poles of Zubiri’s Thought

Roughly speaking, the two poles of Zubiri’s thought are (1) that which is most radical in Aristotle, his conception of essence as the t� tˆ �n e�nai, what makes a thing be what it is; and (2) the phenomenological concept of reality.  His own radical innovation was to weave these two into a unified whole via the new concept of sentient intellection.  But Zubiri radically rethinks both Aristotle’s and the phenomenologists’ legacies; so his concept of essence, his concept of reality, and his concept of intelligence differ in many respects from the originals. 

(1) Zubiri points out that Aristotle begins by conceiving of essence as that which makes a thing what it is, in the most radical sense.  Later, however, Aristotle links his metaphysics with his epistemology by claiming that essence is the physical correlate of the definition (of a thing). Knowledge is then of essences via definition in terms of genus and species; the most famous example is of course “man is a rational animal”.  Zubiri comments:

When the essence is taken as the real correlate of the definition, the least that must be said is that it is a question of a very indirect way of arriving at things. For…instead of going directly to reality and asking what in it may be its essence, one takes the roundabout way of passing through the definition. 8

For Zubiri, this is not merely a roundabout way, but something worse:

…it is a roundabout way which rests on an enormously problematic presupposition, namely, that the essential element of every thing is necessarily definable; and this is more than problematical.9

In fact, Zubiri believes, the essence in general cannot be defined in genus-species form, and may not be expressible in ordinary language at all.  He believes that essences—in the radical sense of determining what a thing is, and thus how it will behave, what its characteristics are, and so forth—can be determined only with great difficulty; and much of science is dedicated to this task.   Specifically, Zubiri believes that it is necessary to go back to Aristotle’s original idea of essence as the fundamental determinant of a thing’s nature, what makes it to be what it is, and expand on this concept in the light of modern science.

But this critique indicates that there is a deep realist strain to Zubiri’s thought, a belief that we can, in some ultimate sense, grasp reality.  The problem arises in connection with our belief that what we perceive is also real—a belief upon which we act in living out our lives.  This compels Zubiri to make an extremely important distinction with respect to reality: between reality in apprehension (which he terms ‘reity’), and reality of  what things are beyond sensing (true reality, realidad verdadera).  Zubiri believes that the failure of past philosophers to distinguish these, and consequently, their failure to recognize that they refer to different stages of intellection, is at the root of many grave errors and paradoxes.  This leads directly to the second pole of Zubiri’s thought: Phenomenology.

(2) Zubiri takes three critical ideas from phenomenology (Husserl, Ortega y Gasset, and Heidegger).  First is a certain way or “idea” of philosophy.  In particular, he accepts that phenomenology has opened a new path and deepened our understanding of things by recognizing that it is necessary to position philosophy at a new and more radical level than that of classical realism or of modern idealism (primarily Hegel).10 This also becomes the basis for Zubiri’s understanding of the relationship of science and philosophy.

Secondly, he accepts that philosophy must start with its own territory, that of “mere immediate description of the act of thinking”.   But for him, the radical philosophical problem is not that proclaimed by the phenomenologists: not Husserl’s “phenomenological consciousness”, not Heidegger’s “comprehension of being”, not Ortega’s “life”, but rather the “apprehension of reality”.  He believes that philosophy must start from the fundamental fact of experience, that we are installed in reality, however modestly, and that our most basic experiences, what we perceive of the world (colors, sounds, people, etc.) are real.  Without this basis—and despite the fact that knowledge built upon it can at times be in error—there would be no other knowledge either, including science.   However, at the most fundamental level, that of direct apprehension of reality, there is no possibility of error; only knowledge built upon this foundation, involving as it does logos and reason, can be in error.  Zubiri points out that it makes sense to speak of error only because we can—and do—achieve truth.11

But because the world discovered to us by science is quite different from our ordinary experience (electromagnetic waves and photons instead of colors, quarks and other strange particles instead of solid matter, and so forth), a critical problem arises which thrusts Zubiri towards a radical rethinking of the notion of reality.  This is one of the main themes of Sentient Intelligence.

The third idea—perhaps ‘inspiration’ is a better term—which Zubiri draws from phenomenology has to do with his radically changed concept of reality.  For Zubiri, reality is a formality, not a zone of things, as in classical philosophy:

In the first place, the idea of reality does not formally designate a zone or class of things, but only a formality, reity or “thingness”. It is that formality by which what is sentiently apprehended is presented to me not as the effect of something beyond what is apprehended, but as being in itself something “in its own right”, something de suyo; for example, not only “warming” but “being” warm. This formality is the physical and real character of the otherness of what is sentiently apprehended in my sentient intellection.12

This conception of reality is, so to speak, a radical “paradigm shift”, because it means that there are multiple types of reality and that many of the old problems associated with reality are in fact pseudo-problems.  Zubiri notes that

The reality of a material thing is not identical with the reality of a person, the reality of society, the reality of the moral, etc.; nor is the reality of my own inner life identical to that of other realities.  But on the other hand, however different these modes of reality may be, they are always reity, i.e., formality de suyo.

Much of the work is devoted to analyzing the process of intelligence, and explaining how its three stages (primordial apprehension, logos, and reason) unfold and yield knowledge, including scientific knowledge.

Sentient Intellection not Sensible Intellection

Zubiri seeks to reestablish in a radical fashion the basis for human knowledge, as the principal step in his restructuring of philosophy.  This task goes far beyond any type of Kantian critique—something that Zubiri believes can only come after we have analyzed what human knowledge is, and how we apprehend.  For Zubiri, perception of reality begins with the sensing process, but he rejects the paradigm of classical philosophy, which starts from opposition between sensing and intelligence.  According to this paradigm, the senses deliver confused content to the intelligence, which then figures out or reconstructs reality.  The Scholastics said, nihil est in intellectu quod prius non fuerit in sensu nisi ipse intellectus.  This is sensible intelligence, and according to Zubiri, the entire paradigm is radically false.

Zubiri’s point of departure for his rethinking of this problem is the immediacy and sense of direct contact with reality that we experience in our perception of the world; the things we perceive: colors, sounds, sights, are real in some extremely fundamental sense that cannot be overridden by subsequent reasoning or analysis.  That is, there is associated with perception an overwhelming impression of its veracity, a type of “guarantee” which accompanies it, that says to us, “What you apprehend is reality, not a cinema, not a dream.”  Implied here are two separate aspects of perception: first, what the apprehension is of, e.g. a tree or a piece of green paper, and second, its self-guaranteeing characteristic of reality.  This link to reality must be the cornerstone of any theory of the intelligence:

By virtue of its formal nature, intellection is apprehension of reality in and by itself.  This in a radical sense an apprehension of the real which has its own characteristics....Intellection is formally direct apprehension of the real—not via representations nor images.  It is an immediate apprehension of the real, not founded in inferences, reasoning processes, or anything of that nature.  It is a unitary apprehension.  The unity of these three moments is what makes what is apprehended to be apprehended in and by itself.13

Thus what we have is a fully integrated process with no distinction between sensing and apprehension which Zubiri terms sensible apprehension of reality.  The fundamental nature of human intellection can be stated quite simply: “actualization of the real in sentient intellection”.14  There are three moments of this actualization:

  • affection of the sentient being by what is sensed (the noetic).
  • otherness which is presentation of something other, a “note”, nota (from Latin nosco, related to Greek gignosco, “to know”, and noein, “to think”; hence the noematic)
  • force of imposition of the note upon the sentient being (the noergic).

Otherness consists of two moments, only the first of which has received any attention heretofore: content (what the apprehension is of) and formality (how it is delivered to us).  Formality may be either formality of stimulation, in the case of animals, or formality of reality, in the case of man.

The union of content and formality of reality gives rise to the process of knowing which unfolds logically if not chronologically in three modes or phases:

  • Primordial apprehension of reality (or basic, direct installation in reality, giving us pure and simple reality)
  • Logos (explanation of what something is vis � vis other things, or what the real of primordial apprehension is in reality)
  • Reason (or ratio, methodological explanation of what things are and why they are, as in done in science, for example)

This process, shown schematically in Figure 1, is mediated by what Zubiri calls the ‘field’ of reality.  The reality field concept is loosely based on the field concept from physics, such as the gravitational field, where a body exists “by itself”, so to speak; but also by virtue of its existence, creates a field around itself through which it interacts with other bodies.  Thus in the field of reality, a thing has an individual moment and a field moment. The individual moment Zubiri refers to as the thing existing “by itself” or “of itself”; de suyo is the technical term he employs. The “field moment” is called as such and implies that things cannot be fully understood in isolation.  This is in stark contrast to the notion of essence in classical philosophy.

Roughly speaking, primordial apprehension installs us in reality and delivers things to us in their individual and field moments; logos deals with things in the field, how they relate to each other; and reason tells us what they are in the sense of methodological explanation. A simple example may serve to illustrate the basic ideas. A piece of green paper is perceived.  It is apprehended as something real in primordial apprehension; both the paper and the greenness are apprehended as real, in accordance with our normal beliefs about what we apprehend. (This point about the reality of the color green is extremely important, because Zubiri believes that the implicit denial of the reality of, say, colors, and the systematic ignoring of them by modern science is a great scandal.) 

Figure 1
Sentient Intelligence in Zubiri’s Philosophy

As yet, however, we may not know how to name the color, for example, or what the material is, or what to call its shape.  That task is the function of the logos, which relates what has been apprehended to other things known and named from previous experience; for example, other colors or shades of colors associated with greenness.  Likewise, with respect to the material in which the green inheres, we would associate it with paper, wood, or other things known from previous experience.  In turn, reason via science explains the green as electromagnetic energy of a certain wavelength, or photons of a certain energy in accordance with Einstein’s relation E=hn.   That is, the color green is the photons as sensed; there are not two realities.  The characteristics of the three phases may be explained as follows:

  • Primordial apprehension of reality is the basic, direct installation in reality, giving us pure and simple reality.  This is what one gets first, and is the basis on which all subsequent understanding is based.  Perhaps it can most be easily understood if one thinks of a baby, which has only this apprehension: the baby perceives the real world around it, but as a congeries of sounds, colors, etc., which are real, but as yet undifferentiated into chairs, walls, spoken words, etc. It is richest with respect to the real, poorest with respect to specific determination (ulterior modes augment determination, but diminish richness).  In it, reality is not exhausted with respect to its content, but given in an unspecific ambient transcending the content.  This transcendence is strictly sensed, not inferred, even for the baby.  Primordial apprehension is the basis for the ulterior or logically subsequent modes.
  • Logos (explanation of what something is vis � vis other things, or as Zubiri expresses it, what the eal of primordial app

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