Medieval philosophy

4. Doctrinal characteristics

At the most basic level, medieval philosophers share a common view of the world that underlies and supports the various specific developments that constitute medieval philosophy’s rich detail.

Metaphysics. The common metaphysical ground of medieval philosophy holds that at the most general level reality can be divided into substances and accidents. Substances – Socrates and Browny the donkey are the stock examples – are independent existents and therefore ontologically fundamental. Corporeal substances (and perhaps also certain incorporeal substances) are constituted from matter and form (see Substance). Matter, which in itself is utterly devoid of structure, is the substrate for form (see Matter). Form provides a substance’s structure or organization, thereby making a substance the kind of thing it is. Socrates’ soul, for example, is the form that gives structure to Socrates’ matter, constituting it as the living flesh and blood of a human body and making Socrates a particular human being. Accidents – Socrates’ height, for example, or Browny’s colour – are also a kind of form, but they take as their substrate not matter as such but a substance: Socrates or Browny. Accidents depend for their existence on substances and account for substances’ ontologically derivative characteristics.

Medieval philosophers recognized matter and form, the fundamental constituents of corporeal substances, as fundamental explanatory principles. A thing’s matter (or material cause) and its form (or formal cause) provide basic explanations of the thing’s nature and behaviour. To these two principles they added two others, the agent (or efficient) cause and the end (or final cause). The agent cause is whatever initiates motion or change; the final cause is the goal or good toward which a particular activity, process, or change is directed.

Medieval philosophers disagreed about extensions and qualifications of this fundamental metaphysical view of the world. They debated, for example, whether incorporeal substances are like corporeal substances in being composed ultimately of matter and form, or whether they are subsistent immaterial forms. They also debated whether substances such as Socrates have just one substantial form (Socrates’ rational soul) or many (one form constituting Socrates’ body, another making him a living body with certain capacities for motion and cognition (an animal), and another making him a rational animal (a human being)). However, they never doubted the basic correctness of the metaphysical framework of substance and accidents, form and matter, nor are they in any doubt about whether the analytical tools that framework provides are applicable to philosophical problems generally.

(See Aristotelianism, medieval; Augustinianism; Eternity of the world, medieval views of; Platonism, medieval.)

Psychology and epistemology. Medieval philosophers understood the nature of human beings in terms of the metaphysics of form and matter, identifying the human rational soul, the seat of the capacities specific to human beings, with form. All medieval philosophers, therefore, held broadly dualist positions according to which the soul and body are fundamentally distinct. But only some were also substance dualists (or dualists in the Cartesian sense), holding in addition that the soul and body are themselves substances.

Medieval philosophers devote very little attention to what modern philosophers would recognize as the central questions of epistemology (see Epistemology, history of). Until very late in the period, they show little concern for sceptical worries and are not primarily interested in stating the necessary and sufficient conditions for the truth of the claim that some person knows a given proposition. For the most part they assume that we have knowledge of various sorts and focus instead on developing an account of the cognitive mechanisms by which we acquire it. They are especially interested in how we are able to acquire knowledge of universals and necessary truths – objects or truths that are immaterial, eternal and unchanging – given that the world around us is populated with particular material objects subject to change. The answers medieval philosophers give to this question vary considerably, ranging from Platonistic accounts that appeal to our direct intellectual vision (with the aid of divine illumination) of independently existing immutable entities (such as ideas in the divine mind) to naturalistic accounts that appeal to cognitive capacities wholly contained in the human intellect itself that abstract universals from the data provided by sense perception (see Universals).

(See Aristotelianism, medieval; Augustinianism; Platonism, medieval.)

Ethics. Medieval philosophers share a generically Greek framework of ethical theory, extended and modified to accommodate Christianity. Its main features include an objectivist theory of value, a eudaimonistic account of the human good and a focus on the virtues as central to moral evaluation (see Eudaimonia; Areté; Virtues and vices). According to the metaphysics of goodness inherited by medieval philosophers from Greek thought, there is a necessary connection between goodness and being. Things are good to the extent to which they have being. Evil or badness is not a positive ontological feature of things but a privation or lack of being in some relevant respect. The ultimate human good or goal of human existence is happiness or beatitude, the perfection of which most medieval philosophers identified as supernatural union with God after this life. The ultimate human good is attained both through the cultivation of the moral virtues and through divine grace in the form of supernaturally infused states and dispositions such as faith, hope and charity, the so-called theological virtues (see Theological virtues).

Within this framework, medieval philosophers debated whether human beatitude is essentially an affective state (a kind of love for God) or a cognitive state (a kind of knowledge or vision of God), and whether the virtues are strictly necessary for the attainment of beatitude. They also debated whether the rightness or wrongness of some actions depends solely on God’s will. Contrary to caricatures of medieval ethics, no one unequivocally endorsed a divine command theory according to which the moral rightness (or wrongness) of all acts consists solely in their being approved (or disapproved) by God (see Voluntarism).

(See Aristotelianism, medieval; Augustinianism; Platonism, medieval.)

Logic and language. Medieval philosophers devote enormous attention – perhaps more attention than philosophers of any period in the history of philosophy apart from the twentieth century – to logic and philosophy of language. This phenomenon is explained primarily by the uniquely important role played by Aristotle’s logic in the development of medieval thought. Until the early twelfth century, medieval philosophers’ knowledge of Greek philosophy was restricted to a few texts of Aristotelian logic and, by default, those texts largely set the agenda for philosophical discussion. It is a passage from Porphyry’s Isagōgē, for example, that enticed first Boethius and, following him, a long line of commentators to take up the philosophical problem of universals (see Universals). The texts of the old logic, which remained a central part of the philosophy curriculum in the later Middle Ages, were eventually supplemented by the remaining treatises of Aristotle’s logic, among which the Topics and the Sophistical Refutations in particular sparked intense interest in the forms of philosophical argument and the nature of meaning.

(See Aristotelianism, medieval; Language, medieval theories of; Logic, medieval.)

Natural philosophy. Medieval philosophers believed that a complete account of reality must include an account of the fundamental constituents and principles of the natural realm. Their earliest reflections on these matters were inspired primarily by two ancient accounts of the origins and nature of the universe, the biblical story of creation (in Genesis) and Plato’s story of the Demiurge’s fashioning of the world (in the Timaeus) (see Plato). The confluence of these ancient sources produced a medieval tradition of speculative cosmological thought paradigmatically expressed in discussions of the six days of creation. This topic in particular gave medieval philosophers opportunity to reflect on the nature of the contents of the universe and the principles governing the created realm.

From the late twelfth century, medieval philosophy is profoundly affected by the new Aristotelian natural philosophy and the new scientific treatises by Islamic philosophers. Aristotle’s Physics in particular received enormous attention, and medieval philosophers developed sophisticated tools of logical, conceptual and mathematical analysis to deal with problems raised by Aristotle’s discussions of motion, change, continuity and infinity. Scientific treatises by Islamic thinkers such as Alkindi (see al-Kindi), Alpetragius, Avicenna (see Ibn Sina) and Alhasen provided the material and impetus for significant developments in astronomy, medicine, mathematics and optics.

(See Aristotelianism, medieval; Eternity of the world, medieval views of; Language, medieval theories of; Natural philosophy, medieval; Oxford Calculators; Platonism, medieval.)