SOURCE: An introduction to Ockham: Philosophical Writings, edited by Philotheus Boehner, Thomas Nelson, 1957, pp. xvi-xxix.

[In the following excerpt, Boehner summarizes the guiding principles used in Ockham's writings and explains some of his terminology.]

… III. Ockham's Philosophy

Before drawing the broad outlines of Ockham's philosophy, we must remind the reader that Ockham never expounded it systematically and in its entirety. The Cursus philosophicus in several ponderous tomes is a characteristic product of sixteenth- and seventeenth-century scholasticism, but no scholastic philosopher of the thirteenth or the fourteenth century has handed down to us anything like that. The scholastics of the thirteenth and fourteenth centuries were theologians essentially, philosophers only incidentally. Their reasoning was a concentrated effort to penetrate the mysteries of the Christian faith; their philosophy was the handmaid of theology. None the less, it is a striking historical fact that these great theologians were equally great as philosophers. Being theologians, they did not care to start by developing a complete philosophy. Rather they developed their theology and philosophy in organic integration, so that theology was constantly fertilised by philosophic speculation and philosophy remained under the guidance of Christian dogma. It was due to this organic unity of medieval speculation that little need was felt for composing a complete philosophical Summa. It is in the theological writings that the best scholastic philosophy is hidden, and it is the task of the historian to extract it from its theological context.

This will be our task, also, when giving an outline of Ockham's philosophy. Some of our texts, in fact a considerable number, have been taken from writings devoted to purely philosophical subjects, many from the Summa logicae, some from his writings on the Physics of Aristotle. But this has been done for practical purposes, because in these later writings Ockham usually presents his thoughts in a more systematic and precise manner. Nevertheless, his epistemology, psychology, ethics and a large part of his metaphysics have to be reconstructed from fragments scattered throughout his theological works. To present these separate pieces as a part of an ordered system inevitably produces a somewhat artificial synthesis; but we hope that our reconstruction will not be too far removed from what may properly be called the philosophy of William Ockham.

1. The leading ideas of Ockham's philosophy

In order to achieve a general understanding of Ockham's work we have to view him as a theologian, who at the same time was a great logician, a keen observer of facts and a man endowed with a sharp critical sense.

Ockham is first and foremost a theologian who by entering the Order of Friars Minor devoted his whole life, and especially his intellectual activity, to the service of God. Hence he is a religious thinker; for him, there can be only one absolute in his world, one thing which alone is necessary, only one reality which is completely self-sufficient, namely God, the supreme author alike of creation and of revelation. In this world, it is God who ultimately matters. God—the living, the wise, the loving, the just, the all-powerful—God alone is absolutely independent; and by God Ockham means a God of absolute unity and simplicity, and at the same time a God threefold in His personality. With due humility the theologian as such submits and bows to this God of his in an act of uncompromising faith. God's revelation, whether as deposited in holy scripture or as embodied in the living tradition of the Church, is accepted by Ockham as the rule of faith. This rule is throughout the guiding principle of his investigations. Once at least he has expressed it in the following words: 'This is my faith, since it is the Catholic faith. For whatever the Roman Church explicitly believes, this alone, and nothing else, I explicitly or implicitly believe'.¹

However, Ockham is also a logician, perhaps the greatest logician of the Middle Ages. Reason is something sacred, a gift from God; hence the laws of reason are to be respected. Passionately, Ockham denounces any encroachment on the duty to follow one's own reasoning, except, of course, the intervention of that higher authority which is the source from which reason itself flows: 'I consider it to be dangerous and temerarious to force anyone to fetter his mind and to believe something which his reason dictates to him to be false, unless it can be drawn from holy scripture or from a determination of the Roman Church or from the words of approved doctors'.²

While Ockham apparently enjoys the display of logic, we look in vain for lofty speculations. Wherever possible, he tries to get a solid footing on experience and observation. We have to find out how things are, we have no right to dictate how things must be. Ockham's philosophy is empirical, but he is no empiricist. He is an empirical thinker, because he is a Christian firmly believing in the contingency of this created world of ours.

Since God is the only absolute and necessary being, knowledge about created beings requires that we should examine them and investigate what they actually are; for, so far as God is concerned, they might be different. Ockham never loses sight of this basic Christian idea—so radically opposed to the necessitarian view—that there is no inherent necessity for anything in this world to be what it is. Even in his investigation of the problems of physics or psychology Ockham never forgets that this world is absolutely dependent on the will of God; always he takes the stand of a Christian, who firmly believes in the omnipotence of God and the contingency of creatures.

Thus the following maxims are the guiding principles of all Ockham's work:

1. All things are possible for God, save such as involve a contradiction.

In other words, God can do (or make or create) everything which does not involve a contradiction; that which includes a contradiction is absolute non-entity. Ockham expressly bases this principle on an article of faith: 'I believe in God the Father Almighty'.³ From this Ockham immediately infers a second principle which is encountered everywhere in his writings:

2. Whatever God produces by means of secondary (i.e. created) causes, God can produce and conserve immediately and without their aid.⁴

Hence any positive reality which is naturally produced by another created being (not of course without the aid of God who is the first cause) can be produced by God alone without the causality of the secondary cause. In other words, God is not dependent on the causality of created causes, but they are absolutely dependent on His causality.

This is stated in a more general manner:

3. God can cause, produce and conserve every reality, be it a substance or an accident, apart from any other reality.⁵

Hence God can create or produce or conserve an accident without its substance, matter without form, and vice versa. In order to bring anything under the operation of this principle, it is sufficient to prove that it is reality or entity.

These rules or guiding principles are theological in nature, as Ockham does not fail to emphasise. The following is, however, a scientific principle of general application:

4. We are not allowed to affirm a statement to be true or to maintain that a certain thing exists, unless we are forced to do so either by its self-evidence or by revelation or by experience or by a logical deduction from either a revealed truth or a proposition verified by observation.

That this is the real meaning of 'Ockham's razor' can be gathered from various texts in Ockham's writings.⁶ It is quite often stated by Ockham in the form: 'Plurality is not to be posited without necessity' (Pluralitas non est ponenda sine necessitate), and also, though seldom: 'What can be explained by the assumption of fewer things is vainly explained by the assumption of more things' (Frustra fit per plura quod potest fieri per pauciora). The form usually given, 'Entities must not be multiplied without necessity' (Entia non sunt multiplicanda sine necessitate), does not seem to have been used by Ockham. What Ockham demands in his maxim is that everyone who makes a statement must have a sufficient reason for its truth, 'sufficient reason' being defined as either the observation of a fact, or an immediate logical insight, or divine revelation, or a deduction from these. This principle of 'sufficient reason' is epistemological or methodological, certainly not an ontological axiom.

The scholastics distinguished clearly between a sufficient reason or cause (usually expressed by the verb sufficit) and a necessary reason or cause (usually expressed by requiritur). As a Christian theologian Ockham could not forget that contingent facts do not ultimately have a sufficient reason or cause of their being, inasmuch as God does not act of necessity but freely; but our theological and philosophical, and in general all our scientific, assertions ought to have a sufficient reason, that is a reason from the affirmation of which the given assertion follows. All created things can be explained ultimately only by a necessary reason, i.e. a cause which is required to account for their existence. For every creature is contingent. The guiding idea of Duns Scotus, to safeguard contingency (servare contingentiam), is present everywhere in the work of Ockham. We can formulate it as follows:

5. Everything that is real, and different from God, is contingent to the core of its being.

If we bear in mind these guiding principles of Ockham, then his philosophical work becomes intelligible as the effort of a theologian who is looking for absolute truth in this contingent world, viz. for truth independent of any of those thoroughly contingent worlds which are equally possible. He is a theologian who views the world from the standpoint of the absolute. Consequently he sees many truths which were called 'eternal' dwindling away in the light of eternity, which is God Himself. The actual order of creatures remains contingent; the possible order of creatures is above contingency. Hence the tendency of Ockham to go beyond the investigation of the actual order, by asking what is possible regardless of the state of the present universe. What is absolutely possible can never be impossible; and in that sense statements about absolute possibility are always true and free from contradiction, and for that reason are necessary. Thus the work of Ockham also becomes intelligible—and this is only the converse of the former viewpoint—as the effort of a philosopher who is constantly reminded by the theologian in himself that he must not call any truth necessary unless it can be shown that its denial implies a contradiction.

Such a theologian, and such a philosopher, stands in need of a refined and powerful logic, since he is always looking beyond facts and the actualities towards absolute being and absolute possibility. Ockham was, therefore, bound to be more interested in logic than any of his predecessors. This being so, we must acquaint ourselves as closely as possible with Ockham's highly developed logic, and it is for this reason that so much of our text consists of passages from his writings on logic.

It will now be our task to present a rounded picture of Ockham's philosophy as reflected by the texts in this volume. We shall do it according to a certain system, but we wish to repeat that Ockham himself never presented a system of philosophy.

2. Epistemology

Right at the beginning of our exposition we are faced with difficulties of terminology. The highly technical language of Ockham does not always allow of a simple rendering into English. Such is the case with the term 'scientia', which may assume various shades of meaning, ranging from the unqualified knowledge of a truth to scientific knowledge in the strict sense; and again, it might mean groups of such pieces of knowledge (for instance a demonstration), or a system of such pieces of knowledge, e.g. the science of logic or of physics. Here we shall merely describe one very important meaning.

Scientific knowledge in the strict sense.

Ockham's ideal of scientific knowledge is extremely high. He knows that any cognition of a truth may be found in the various sciences; however, his ideal of a strictly scientific knowledge is the same as that developed by Aristotle in the Posterior Analytics. According to Aristotle those propositions only are scientifically known which are obtained by a syllogistic process from evident propositions which are necessary, i.e. always true and never false. Hence Ockham will admit that there is scientific knowledge in this strict sense only when we know a proposition which remains true regardless of our existing world. All the truths of logic and of mathematics, and some statements about God, and many metaphysical propositions, conform to the definition of scientific knowledge given above, for they are necessary conclusions obtained from necessary and evident premises. But no statement of actual fact about this world is in this sense truly a scientific statement. However, modal or conditional propositions about our world may have the necessity required by the definition of scientific knowledge. It is understood that a revealed truth which cannot be known by natural reason fails to satisfy the definition, since it lacks the required self-evidence. When reading Ockham, we must always keep it in mind that scientific knowledge in the strict sense is the result of a demonstration; Ockham admits that we can have evidence for, and convincingly prove, many statements, but they are scientifically or demonstratively known only if they fulfil the requirements of the above definition.

Intuitive and abstractive cognition.

The field of scientific knowledge is limited. But many statements outside this field are true and evident and even necessary, and therefore known with certainty. How do we arrive at them? The answer to this question is of ultimate importance. Our cognition starts with the apprehension not of necessary but of contingent facts. No knowledge of any kind is possible without a direct or indirect contact with some object that is experienced. Since it is generally admitted that in the real order only individuals exist, the realities primarily known to us must be individuals or singular facts, whether these be objects of sense or of intellect, whether outside or within the mind. This first, immediate cognition is called by Ockham, following Duns Scotus, intuitive cognition. It is the basis for a self-evident existential statement, viz. that the thing which is experienced exists, is present, has such and such a condition, etc. It is to be noted that the existential judgment is an operation of the intellect alone, and that the intuitive cognition which is at the basis of it, even if it concerns an object of sense, is an intellectual intuitive cognition or a primary intellectual awareness of an object. The intellect could not have an intuitive cognition of a sensible object without the help of sensory cognition, at least in the natural order; but the intellectual awareness relates to the sense-object as immediately as the sensory cognition does.

Now there is another sort of cognition of an object in which we are not aware of its actuality; it is knowledge simply and solely of the object and therefore abstracts from its existence or non-existence. For instance, a few minutes ago I saw a cloud; I had an intuitive cognition of this cloud, and on the basis of this cognition I gave my assent to the evident judgment 'There is a cloud'. I do not now see this cloud any more, but I think of it, I have it in my mind; this latter knowledge or cognition cannot be the ground for assent to the evident existential judgment 'This cloud exists', for it does not imply the actual existence of this cloud at this time. It abstracts, therefore, from the existence or non-existence of the object and for that reason is called an abstractive cognition; it need not be abstract in the sense of 'universal'. Both cognitions are caused by the object and the intellect. They are the result of a causality in which the object and the intellect co-operate to produce an act of intellection or cognition. Hence both intuitive and abstractive cognition represent real objects outside or inside the mind. Ockham, therefore, is a realist in his epistemology.

Intuitive cognition of non-existents.

Ockham thus holds that intuitive cognition must be caused by two part-causes. There is no doubt that there cannot be an intuitive cognition without the knowing subject; is it possible that there can be an intuitive cognition if the object itself or its causality is lacking? It would seem that if the only part-cause present is the intellect, this is impossible; and Ockham does not deny this. However, Ockham as a Christian theologian believes in the omnipotence of God; one of the guiding principles of his work is that everything that can be produced by a secondary cause can also be produced by the first cause, God. No object, therefore, is necessary, because God can supply the causality of the one secondary partial cause, viz. the object, and co-operate with the other part-cause, the intellect, to produce an intuitive cognition. This He can do, even if the object so known is far away or is for other reasons inaccessible to a direct contact with the intellect. Thus far we are dealing with an object that really exists but is intuitively known and judged to exist only by supernatural aid. But is intuitive cognition also possible, if there is no object?

Ockham's complete definition of intuitive cognition is that it makes possible an evident judgment that a thing exists (or is present etc.) if it exists, or that a thing does not exist if it does not exist. By definition, therefore, intuitive cognition has reference to the existent order. Hence when it is said that one can intuitively know an object which does not exist, it must immediately be stipulated that the object—though not existing in fact—must be an object that might exist. Pure nothingness (i.e. what involves a contradiction, or an impossibility) cannot be known intuitively.

At first sight this may seem surprising. Is it not indeed a contradiction to say that we can have an intuitive cognition of something which does not exist? Ockham does not think so, because as a Christian theologian he knows that God Himself has immediate and non-inferential cognition of everything, whether it exists or not. God knows immediately—and that is to say intuitively—not only all that exists, but also all that could exist, but does not. If such a cognition is possible to God, we must allow that it is possible absolutely speaking; therefore it cannot involve a contradiction. And, according to Ockham's other guiding principle, that which does not involve a contradiction can be realised by God. As a Christian theologian, Ockham maintains that an intuitive cognition of non-existent things is possible with the supernatural help of God; as a philosopher, he maintains also that even in this case the statement 'This thing does not exist' is evident—because intuitive cognition is the basis of an evident and hence absolutely true statement that a thing exists or does not exist, as the case may be. Ockham never doubted the infallibility of evident knowledge.

Abstract universal cognition.

Though an intuitive cognition could itself be called a concept, usually the term 'concept' is reserved for that abstractive cognition which results from comparing together several abstractive cognitions of singulars. By this process of comparison a more general abstractive cognition is formed: a universal concept, predicable of many singulars. What does the universal concept represent?

Ockham refuses to admit that in the real world there is anything that corresponds to the universality of a concept; in other words, he does not admit any universal in re, common nature, etc.—anything which is not completely individual. It is by no means self-evident, says Ockham, that in its own right the nature or essence of a thing is not individual. Almost all his predecessors had maintained that natures and essences considered in themselves had some kind of generality or commonness; in order to become numerical units or individuals or singulars, natures had to be individualised by a principle of individuation. Ockham's predecessors had thus approached this problem from the side of the universal; Ockham attacked it from the side of the individual; a change of outlook almost as epoch-making as the Copernican revolution in astronomy.

Here it is instructive to take a quick glance in passing at the teaching of Duns Scotus. He still held that concerning universals two questions may properly be asked: (1) How can a nature or essence which by itself is not singular become singular? (2) How is it that the same nature or essence becomes a universal concept in the mind? The first question Scotus answers by his theory of individuation. Ockham, however, considers this question a pseudo-problem. To him it is self-evident that everything that exists is individual and singular, so that it does not need to be individualised or singularised. We do not need an explanation for the fact that something is an individual—though of course we need an explanation for the facts that it exists and that it has such or such a nature. Thus Ockham reduces the questions that can properly be asked concerning commonness and individuality to one question, viz. 'What is it that makes a concept a universal concept?' or 'How, by means of universal concepts, can I know individual natures?'

As already stated, Ockham's answer is that a concept, for instance the concept 'man', arises out of the combination of an intuitive with an abstractive cognition. The abstractive cognition alone survives and is stored in the memory as habitual knowledge; it is generalised by way of comparison with other similar abstractive cognitions to represent, not just one, but many similar individuals. Because of its origin, and because of the similarity between the individuals, it is common to all individuals of the same kind, in the sense that it is predicable of them. Universality, therefore, is simply a manner in which a sufficiently generalised abstractive cognition is predicable, and thus it exists wholly within the mind. On the side of the individuals that are known, there exists only individuality and the similarity of individual natures.

The nature of the universal concept. In answer to the question stated above, Ockham did not hesitate between various possibilities. But there is a further question. What is the nature of a universal concept considered in itself; what kind of being does a universal concept have in the mind? At different periods Ockham gave different answers to this question. Originally he had believed that the universal concept (for instance 'man' or 'animal' in the mental proposition 'Man is an animal') is something different from the act of thinking it, (that is, the intellection), and that the concept has no reality but only a logical being, as an object of the act of thinking (or, in medieval language, that it has no esse subiectivum but does have esse obiectivum). As a mere thought-object it has neither a spiritual, or psychic, nor a material reality; it is something mentally imaged, and for that reason Ockham calls it a fictum. A fictum, however, is not a figmentum, or a fiction in the modern sense; the latter being defined as something that is quite impossible, or purely fictitious. This logical picture or fictum is considered to be a true representation of the object in connexion with which it was first constituted in its proper being by the process of intuitive and abstractive cognition.

This theory was held not only by Ockham in his earlier period, but also by his contemporary Aureoli. Ockham and Aureoli seemed to have arrived at it independently of one another; but it appears that when Ockham became acquainted with Aureoli's Commentary on the Sentences he gradually gave up his fictum theory in favour of another. This other theory we shall call the 'intellection theory'. According to this, the concept or universal involved in a cognition is identical with the very act of abstractive cognition, hence it is a psychical entity; this act of cognition, immediately caused by the object known and the intellect working together as two part-causes, represents the object, and as such can function as predicate in a mental proposition.

All the evidence suggests that Ockham finally held only the intellection theory and, in his later years, completely abandoned the fictum theory.…

Notes

…¹De sacramento altaris, cap. I; ed. Birch, p. 164, 3-5.

²De corpore Christi (De sacramento altaris in the ed. of Birch), ed. Birch, p. 126, 18-23.

³Cf. Quodlibeta VI, qu. 6, of the Strasbourg edition.

⁴Ibid.

⁵Cf. Reportatio II, qu. 19F.

⁶Cf. De sacramento altaris, cap. 28; ed. Birch, p. 318. In Ordinatio d. 30, qu. IE, we read: 'Nothing must be affirmed without a reason being assigned for it, except it be something known by itself, known by experience, or it be something proved by the authority of holy scripture'. Reportatio II, qu. 150 has the following wording: 'We must not affirm that something is necessarily required for the explanation of an effect, if we are not led to this by a reason proceeding either from a truth known by itself or from an experience that is certain'. It should be noted that various formulations of 'Ockham's razor' are already found before Ockham, for instance in Duns Scotus. The oldest scholastic thinker, so far as we know, who formulated it, gives this version: 'Frustra fit per plura quod potest fieri per unum', Odo Rigaldus, Commentarium super Sententias, MS. Bruges 208, fol. 150a.