William of Ockham (c.1285-c.1349) was an English philosopher, logician, and theologian. He was born in the village of Ockham, county of Surrey. He died in the city of Munich (in Bavaria). Ockham wrote extensively on many subjects, including logic, epistemology, the philosophy of language, metaphysics, ethics, and theology. His philosophical writings included the Summa Logicae (Summa of Logic, c.1328), the Expositio in libros Physicorum Aristotelis (Exposition of the Books of Physics of Aristotle, 1322-24), and the Tractatus de praedestinatione et de praescientia Dei et de futuris contingentibus (Treatise on Predestination and on God's Foreknowledge of Future Contingents, 1321-24).

His theological works included: In Libros Sententiarum (Commentary on the Sentences of Peter Lombard, 1317-18), and the Quodlibeta Septem (Seven Quodlibets, 1322-25).

His political writings included: Dialogus Inter Magistrum et Discipulum de potestate Papae et Imperatoris (Dialogue between Master and Disciples on the Power of Emperors and Popes, 1334-47), and his Octo quaestiones de potestate papae (Eight Questions on the Power of the Pope, 1340-44).

In his approach to the philosophy of language, Ockham was an important proponent of nominalism, the doctrine that only particulars, and not universals, are real. Ockham taught that universal terms are merely names which are attached to particular things, and that universal terms are merely linguistic devices which we use to try to understand reality. In his approach to metaphysics and epistemology, Ockham used a method of logical empiricism, asserting that intuitive knowledge is prior to abstractive knowledge, and that abstractive knowledge must be based on intuitive knowledge. He thus had an important influence on modern empiricist philosophy.

Ockham’s theory of cognition is presented in works such as the Summa Logicae, the Quodlibeta Septem, and the Prologue to the Ordinatio (the Commentary on the First Book of Sentences).

Ockham makes a basic distinction between the sentient and intellective soul. The sentient soul is extended and material, but the intellective soul is non-extended and non-material. The sentient soul is the type of soul which belongs to a physical creature (such as an animal), but the intellective or rational soul is the type of soul which belongs to a spiritual creature (such as an angel).¹ A human soul is a composite soul of sentient and intellective power and capability. The sentient soul is capable of physical sensation, but the intellective soul is not capable of physical sensation. In a human being, the sentient and intellective activities of the soul may be in harmony with each other, or may be in conflict with each other. The appetites and desires of the sentient soul may be accepted or rejected by the intellective soul.

In Ockham’s theory of the nature of human volition, the will is the capacity of the intellective soul for acting, or not acting, upon the desires of the sentient soul. The will may be active or passive. While the will may, or may not, act on the desires of the sentient soul, the intellective capacity for judgment or understanding may, or may not, act on the desires of the will.

Ockham distinguishes between apprehension and judgment as acts of the intellective soul. Apprehension is an act whereby the intellect becomes aware of an object. Apprehension may be of simple objects (e.g. pleasure or pain) or of complex objects (e.g. sentences or propositions). Acts of judgment, on the other hand, are only concerned with logical propositions (i.e. complex objects). A judgment is expressed by an act of assenting to, or dissenting from, a proposition. Ockham explains, in the Prologue to the Ordinatio, that the act of judging a proposition presupposes an apprehension of that proposition. Furthermore, the act of judging a proposition presupposes a non-complex cognition of the terms (or elements) of that proposition.

According to Ockham, a proposition which has been apprehended may not be judged if it is indifferent (i.e. if the intellect neither assents to, nor dissents from, it). Moreover, if a proposition has been frequently apprehended, then a 'habit' of apprehending or judging that proposition may develop, and this 'habit' may influence the intellect toward an act of apprehension, or toward an act of judgment. A 'habit' of apprehending or judging a proposition may also allow the intellect to remember previous thoughts, judgments, or acts of willing.

Ockham claims that apprehension of simple objects may produce two kinds of cognition: 1) intuitive and 2) abstractive. Intuitive cognition may occur if an object is present for intuition. Abstractive cognition may occur if an object is no longer present for intuition. Intuitive cognition provides knowledge of whether or not an object exists. Abstractive cognition does not provide knowledge of whether or not an object exists. Intuitive cognition can only occur if an object of intuition exists, but abstractive cognition can occur even if the object of intuition no longer exists.

According to Ockham, intuitive cognitions are the original, primary intuitions of singular objects. Abstractive cognitions of singular objects occur secondarily after these objects have been apprehended intuitively. Abstractive cognitions of singular objects cannot occur without prior intuitions of the same objects. However, singular objects which have ceased to exist for intuitive cognition may remain objects of abstractive cognition.

Ockham argues that only by divine power can non-existing objects become objects of intuitive cognition. Non-existing objects cannot become objects of intuitive cognition by natural causes alone. If an intuitive cognition is caused to exist, then there must have been an object which caused it to exist. If we can actually see an object, then there must be an object which can actually be seen. Intuitive cognitions cannot be caused by objects which do not exist, unless these cognitions are caused by God. The existence of an intuitive cognition as an effect of an object implies that there was an existing object which caused the cognition to occur. However, God may freely cause intuitive cognitions of non-existing objects.

Ockham contends that cognitions are caused by the combined operation of the intellect and of the object of cognition. The intellect and the object of cognition combine to cause the act of cognition.

Ockham argues that intuitive cognition of non-existing objects is possible for God, because God knows everything that exists, and everything that does not exist. God’s knowledge of everything that exists and that does not exist is not caused by any existing or non-existing object, because every object is ultimately caused to exist, or not to exist, by the will of God. Ockham explains that this is not contradictory to the existence of cause-and-effect relationships, because any effect of an intermediary cause can be caused directly by God, and because God does not determine that cause-and effect relationships should be contradictory to each other. Furthermore, if an intuitive cognition of the presence of God is caused to occur in any human being, then this intuitive cognition cannot be caused to occur without the actual presence of God.

According to Ockham, intuitive cognition enables us to apprehend the existence, or non-existence, of an object, but abstractive cognition does not enable us to apprehend the existence, or non-existence, of an object. Intuitive cognition provides knowledge of contingent truths, but abstractive cognition does not provide knowledge of contingent truths. Intuitive cognition is the basis of our empirical knowledge of the world.

Contingent truths may become evident by intuitive cognition. Evident truths are knowable truths, of which we can have objective certainty. Knowledge of contingent truths may be a means of knowing necessary truths. Necessary truths may become evident by abstractive cognition.

Evident truths are known by either intuitive or abstractive cognition. Non-evident truths are not known by either intuitive or abstractive cognition. Non-evident truths may become evident, if they become known by intuitive or abstractive cognition. Evident truths may become non-evident if they are no longer knowable by intuitive or abstractive cognition.

Ockham says that matters of faith cannot be proved evidently.² Thus, many complex propositions (e.g. regarding the existence of God) may, or may not, be able to be proved evidently, depending on whether they are considered to be matters of reason or matters of faith.

Ockham contends that singular things, and not universals, are the original objects of cognition. Intuitive cognition of a singular object is required for abstractive cognition of that same object. Abstractive cognition of a singular object presupposes an intuitive cognition of that same object.³ Intuitive cognition of a singular object does not presuppose an abstractive cognition of that same object.

Ockham explains that simple, primary cognitions which are 'proper' to singular objects are intuitive. Simple, primary cognitions which are 'proper' to more than one object are abstractive. A concept which is 'proper' to a singular thing refers only to that singular thing. A 'common' concept is not 'proper' to a singular thing, but refers to more than one thing. A 'proper' concept is also a 'non-common' concept, i.e. a concept which refers only to one thing and not to more than one thing or to what more than one thing have in common.

Ockham also says that a simple cognition of a singular thing does not cause a first, simple, and 'proper' cognition of another thing. A first, intuitive cognition of a singular thing is 'immediately' caused by the thing itself, unless the cognition is 'immediately' caused by God.⁴

A cognition is 'proper' to a singular thing if it is 'immediately' caused by that thing, and not by any other thing. Thus, a 'proper' and simple cognition of any singular thing can only occur if cognition can yield specific knowledge of that thing.⁵

A singular thing is not only numerically single, but is specifically single, in that it is not a signifier of other things. A universal is a numerically singular thing, in that it refers to a singular quality which may be predicated of many things, but it is not a specifically singular thing, in that it is a signifier of, and may be predicated of, many things.

According to Ockham, a universal is not something which exists outside the mind. There is no universal substance existing outside of the mind.⁶ Every substance existing outside the mind has a particular nature and a particular form. Universals are only concepts, or thought-objects, and have no reality outside the mind. Universals are mental representations of the real world.

Ockham describes the relation of a simple intuitive cognition to its object as a relation of 'first intention.' The relation of an abstractive cognition to an object which is no longer present for intuition is a relation of 'second intention.' First intentions correspond to an external reality. Second intentions are merely thought-objects, and have no reality outside the mind.⁷

'Ockham’s razor' is a principle of conciseness and precision in reasoning, which asserts that abstractions and generalities should be reduced to a minimum. 'Ockham’s razor' is the principle that 'plurality should not be posited unless there is a necessity to do so.' 'Proper' concepts of singular things should not be expanded needlessly, since abstract concepts or universals may not correspond with any existing reality.

Intuitive or abstractive cognitions may be simple, composite, or complex. A simple intuitive cognition is an intuitive cognition of a singular thing. A simple abstractive cognition is an abstractive cognition of more than one thing, and thus is not 'proper' to a singular thing. A composite abstractive cognition may be 'proper' to a singular thing. A composite intuitive cognition of a singular thing may include multiple intuitions of that thing, and thus may also be 'proper' to a singular thing.

Intuitive or abstractive knowledge may be clear or unclear, specific or non-specific, definite or indefinite. In some cases, intuitive cognition may only be able to establish the existence of an object, without providing specific information about the nature of the object. Further inquiry concerning the nature of the object may occur by means of abstractive cognition. In other cases, intuitive cognition may not only be able to establish the existence of an object, but may be able to provide specific knowledge about the nature of the object.

In Ockham’s theory of knowledge, it is possible by means of reflection to have an intuitive cognition of an existing abstractive cognition, or to have an abstractive cognition of an intuitive cognition. The intellect may know its own acts intuitively or abstractively. Thus, Ockham distinguishes between direct and reflexive acts of the intellect. A direct act apprehends an object, while a reflexive act apprehends a direct act. Reflection enables the intellect to apprehend its own acts, and to make judgments about them.

Ockham contends that the intellective soul which is capable of acts of willing may be both active and passive in causing its own acts. Acts of will may be interior or exterior to the intellective soul. An exterior act may, or may not, conform to an interior act. Good or evil may belong to an interior act or exterior act. Both the exterior act and interior act may have their own 'proper' goodness or badness. The goodness which belongs to an exterior act may depend on whether it conforms to an interior act of will, and whether the interior act was good. The goodness which belongs to an interior act may depend on the reasons and motives for the act. An act which is under the control of the will may not have the same moral quality as an act which is not under the control of the will.

Ockham claims that repeated acts of willing may generate a 'habit.' A 'habit' is a tendency to repeat the same acts of apprehending, judging, or willing. Thus, virtue may be a 'habit' of the will. 'Habits' may be good, bad, or indifferent. The moral quality of a 'habit' may depend on whether the 'habit' is voluntary or involuntary. 'Habits' may be as different as the acts which generate them.

In some cases, the intellect may not be able to perform an act unless it has acquired a 'habit' of performing that act. If the intellect loses the 'habit' of performing an act, the intellect may sometimes lose the ability to perform that act. Thus, a 'habit' may be an 'efficient' cause of an act. Every 'habit' is caused by an act, but not every act is caused by a 'habit.'

Ockham accepts Aristotle’s doctrine of the Four Causes, which describes the basic principles by which things come into being. All things have: 1) a 'material' cause, 2) a 'formal' cause, 3) an 'efficient' cause, and 4) a 'final' cause. A 'material' cause is the material (or substance) out of which a thing comes into being. A 'formal' cause is the shape (or form) into which a thing comes into being. An 'efficient' cause is the agent by which a thing comes into being. A 'final' cause is the reason for which a thing comes into being.

A cause of an effect may be 'mediate' (indirect) or 'immediate' (direct), 'total' or 'partial,' 'proximate' or 'remote,' 'potential' or 'actual.' Ockham argues that the 'final' cause of an effect may not always be distinct from the 'efficient' cause of the same effect (Quodlibeta, IV, Q. i). For example, God may be both the 'efficient' and 'final' cause of the same effect.

Ockham rejects the view of John Duns Scotus (1265-1308) that universals have a formal existence outside the mind, and that universals correspond to real things in the empirical world. Ockham argues that, according to this view, singulars and universals are formally distinct, but not really distinct. Ockham contends that individual difference cannot be the same as common nature, and that singulars and universals are really distinct and different things.

¹Elizabeth Karger, "Ockham’s Misunderstood Theory of Intuitive and Abstractive Cognition," in The Cambridge Companion to Ockham, edited by Paul Vincent Spade (Cambridge: Cambridge University Press, 1999), p. 205.
²William of Ockham, "First Quodlibet, Question 1," in Quodlibetal Questions, Volume I, translated by Alfred J. Freddoso and Francis E. Kelley (New Haven: Yale University Press, 1991) p. 5.
³Ockham, "First Quodlibet, Question 13," ibid., p.65.
⁴Ockham, "Fourth Quodlibet, Question 17," ibid., p. 315.
⁵Ockham, "First Quodlibet, Question 13," ibid., p. 65.
⁶Ockham, "Summa totius logicae, I, c.xv" in Philosophical Writings: A Selection, translated by Philotheus Boehner (Indianopolis: Hackett Publishing Company, 1990), o. 35.
⁷Ockham, "Ordinatio, D. II, Q. viii, prima redactio," ibid., p. 43.

Karger, Elizabeth. "Ockham’s Misunderstood Theory of Intuitive and Abstractive Cognition," in The Cambridge Companion to Ockham, ed.by Paul Vincent Spade. Cambridge: Cambridge University Press, (1999), pp. 204-226.

Moody, Ernest A. "William of Ockham," in The Encyclopedia of Philosophy, ed. by Paul Edwards. New York: Crowell, Collier and MacMillan (1967), pp. 306-317.

Ockham, William of. Quodlibetal Questions, Volumes 1 and 2. Translated by Alfred J. Freddoso and Francis E. Kelley. New Haven: Yale University Press, 1991.

Ockham, William of. Philosophical Writings: A Selection. Translated by Philotheus Boehner. Indianapolis: Hackett Publishing Company, 1990.