By “post-medieval Augustinianism” I shall mean characteristically Augustinian concepts, questions, arguments, responses, and ways of thinking that are prominent in various modern philosophers, whether or not those philosophers ever acknowledge the Augustinian provenance of these aspects of their own thinking. On this way of understanding “Augustinianism ” Descartes is perhaps the most Augustinian of modern philosophers, even though Descartes himself declined to acknowledge that there was any significant affinity between his own thought and that of Augustine (let alone that Augustine had actually influenced his thinking!). Both because Descartes was so profoundly Augustinian in his ways of thinking and because he inaugurated the “post-medieval” period in Western philosophy, I shall begin with him.

In 386, at the age of 32, Augustine converted to Christianity. As he tells the story in the Confessions, the complex and dramatic events that constituted his conversion brought to successful conclusion a search he had begun as a teenager at Carthage with his reading of Cicero's Hortensius. Cicero had inspired in him a passionate yearning for the sort of immortality that comes with wisdom. After more than a decade of fruitless searching, Augustine finally discovered that the wisdom he had longed for was to be found with the God of Christianity. The discovery came in a moment of intellectual vision in which Augustine glimpsed and thereby came at last to understand the divine nature. “At that moment,” he tells us, “I saw [God's] 'invisible nature understood through the things that are made' [Romans 1.20]” (Conf. 7.17.23).

Before his conversion to Christianity, Augustine conceived of God as a supremely good being who is “incorruptible, inviolable, and immutable ” (Conf. 7.1.1). At the same time, he was aware of the existence of evil in the world, evil that can be divided into two major classes. First, physical objects have limitations and defects. In particular, the limitations of living things result in hardship, pain, illness, and death. Secondly, there are people who behave wickedly and whose souls are characterized by such vices as pride, envy, greed, and lust.

Augustine regards ethics as an enquiry into the Summum Bonum: the supreme good, which provides the happiness all human beings seek. In this respect his moral thought comes closer to the eudaimonistic virtue ethics of the classical Western tradition than to the ethics of duty and law associated with Christianity in the modern period. But even though Augustine addresses many of the same problems that pagan philosophers do, he often defends very different answers. For him, happiness consists in the enjoyment of God, a reward granted in the afterlife for virtue in this life. Virtue itself is a gift of God, and founded on love, not on the wisdom prized by philosophers.

The topic of Augustine's political philosophy must be approached with care. Augustine never devoted a book or a treatise to the central questions of what we now call “political philosophy.”Unlike Aristotle, he did not attempt serially to address them and to draw out the institutional implications of his answers. Unlike Thomas Hobbes, he did not elaborate a philosophical theory of politics, if by that is meant a synoptic treatment of those central questions which relies on theoretical devices contrived for the purpose. Discussions of politics can be found in a number of Augustine's writings, but these are generally conducted in service of conclusions which neither we nor he would regard as philosophical. Indeed it is questionable whether Augustine thought that political philosophy has a subject-matter which should be sharply distinguished from the subjectmatters of other areas of philosophy or of political enquiry. His own treatments of political subjects draw heavily upon ethics, social theory, the philosophy of history, and, most importantly, psychology and theology. It is possible to recover a distinctive set of political views from Augustine's texts. That set constitutes not a political philosophy, but a loose-jointed and heavily theological body of political thought which Augustine himself never assembled. It does not fit comfortably into any one of the disciplinary categories now standardly associated with the study of politics.

Augustine began writing commentary on scripture not long after his conversion. His first such work, meant as a counterblast to Manichaean attacks on the creation account, was De Genesi contra Manichaeos (388-390). In many ways it sets the tone for much of his later work: Augustine admits an allegorical sense but warns against overenthusiasm for allegory and denigration of the literal sense; we see also from the outset Augustine's interest in scripture as a controversialist and polemicist. After his ordination to the priesthood in 391, he seems to have gone through something of a writer's block, starting but leaving incomplete a treatise on exegetical theory (De doctrina christiana, begun 396 but not completed until 427), another commentary on Genesis (De Genesi ad litteram imperfectus liber, 393-394), and an exposition of Romans (Epistolae ad Romanos inchoata expositio, 394-395). He did manage to finish a verse-by-verse commentary on Galatians, giving the literal sense (Epistolae ad Galatas expositio, 394-395) and a commentary on the Sermon on the Mount (De sermone Domini in monte, 393-396). His Expositio quarundam propositionum ex epistola ad Romanos (394) derives from conversations with the monks at Hippo, who recorded his answers to their questions about Romans; Augustine tells us later that he missed what he eventually came to see as the main point of the epistle.

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Philosophers have come to speak of an Augustinian picture of language. The picture is not really Augustine's, as we shall see, but it makes a good starting point for exploring what his views actually were. Those views, though not as crude as the “Augustinian picture,” will turn out to be mainly unoriginal, following a tradition that was already several hundred years old in his day, and helping to sustain that tradition for a further millennium and more. We know better now, thanks mainly to the fundamental insights of Frege and Wittgenstein.

In writing De Trinitate Augustine had three main objectives. He wished to demonstrate to critics of the Nicene creed that the divinity and co-equality of Father, Son, and Holy Spirit are rooted in scripture. He intended to tell pagan philosophers the need for faith in a divine mediator so that divine self-revelation and redemption can occur. Finally, he wanted to convince his readers that salvation and spiritual growth are connected with knowing themselves as images of the Triune God, from whom they came and toward whom they go, with a dynamic tendency to union realized by likeness to God who is Love.

That a spoken sound is significant is a function of its having an internal correlate in the mind. In semantic contexts, Aristotle identifies the mental state with a logos treated as a meaning or a specification of meaning in a definition. This condition on meaningful sounds is augmented by the requirement that true sentences must also correspond to extralinguistic states of affairs. A true sentence is reducible to an internalized logos, its meaning, since the sounds and/or graphic representations of it are signs of the mental state. Thus the correlation between the internal content and the external object specified by the theory of meaning becomes a threat to the existence of knowledge – or at least to our having any confidence that any particular sentence or body of assertions, such as those making up a demonstrative science, are true. Aristotle seeks to defuse this threat by in effect contextualizing the two relevant aspects of meaning, the pathema as a logos that is expressible in a natural language and the pathema as a likeness to an extralinguistic object. The context in which these are considered in the Posterior Analytics is the theory of demonstrative science, specifically, the theory of definition and the account of the origin of universals. The basic sentences or premises of a demonstrative science are true ex hypothesi. A demonstrative science is a deductive science, moreover, and this means that definitions of basic objects will be included among the primary premises.

In De Interpretatione 1, no sooner has Aristotle asserted that the mental states that words stand for are likenesses of the pragmata of the world, than he dismisses this topic with the words:

The place in the De Anima that Aristotle has in mind in the De Interpretatione is not easily discovered. Nor is it entirely clear which features of the theory of meaning will or should be explained there. Is it merely the nature of the psychic pathemata (internal states) or the likeness obtaining between the pathemata and their external correlates (pragmata)?

Speech is not mentioned in its own right in the De Anima but only in connection with hearing.

Here the intent is to differentiate between speech and other types of noises produced by the respiratory system. What the passage adds to the De Interpretatione's description is the explicit mention of imagination (τασία).

No sooner has Aristotle summarized his theory of meaning in the De Interpretatione than he turns to the topic of sentences. Sentences are the basic linguistic item to which truth values can be assigned, and they are made up of linguistic units that have meaning. To avoid the problems of the Cratylus, Aristotle draws a sharp distinction between the basic units of meaning and the basic truth-functional entities. He also acknowledges that language has functions other than assertion. That said, sentences have truth values in virtue of what is expressed by the sentence, and this is a function of the meaning of the parts of a sentence. A sentential part has a meaning just in case it is a conventional sign for a thought, the content of which is determined by its relation to an object that is external to the thought. Combining terms to make an assertion yields a statement that expresses a nexus of external features. Whether the assertion is true or not depends upon whether this nexus obtains in fact. Certain peculiarities of Aristotle's discussion of truth – more accurately described as a discussion of falsity – fall into place when one recognizes that Aristotle's starting point is a conception of truth-functional entities that are compounds. These compounds are constructed from meaningful (but not independently truth-functional) linguistic units. Similarly, certain peculiarities of his conception of necessity fall into place when it is recognized that for Aristotle the force of the necessity predicate is to indicate that the nexus of features always obtains.

This book began as a paper on De Interpretatione 1, 16a3–8:

This description is Aristotle's only explicit attempt to define meaning, and it has been, as a recent commentator remarked, “the most influential text in the history of semantics.” Notwithstanding, the account of meaning found in these lines was dismissed by John Ackrill as inadequate, and Aristotle has found few defenders in more recent literature. Suspecting that the negative assessment had been too hasty, I set out to discover whether Aristotle might, after all, be right about meaning. Framing the issue in this way proved jejune, and my initial query was replaced by a series of questions: What position is Aristotle taking here? Is it an account of meaning in the modern sense? Is this account one that he tries out in a relatively early work and later rejects? Does the conception of language embodied in these lines help us better understand the linguistic and ontological notions of definition and universals that are key players in Aristotle's epistemology and metaphysics?

Granted, the theory of meaning expressed in these lines is puzzling. Two troublesome relations are posited – one between a significant sound and an internal state and the other between that state and the external object of the state.