The medieval worldview effected a happy if strenuous synthesis between Aristotelian cosmology and Christian theology. The appeal of Aristotle’s conception of the cosmos was that it made nature intelligible to human comprehension. The cosmos was anthropocentric in design, finite in size, spherical in shape, and interconnected in and out, top to bottom–from the mutable and perishable sublunary realm where humans dwelled to the farthest reaches of the immutable and eternal celestial realm where the Unmoved Mover resided. In this conception, each element had its natural place, earth being closest, followed by water, then air, and finally fire. If every being had its place in this steady state which was without absolute beginning or end, each also had its essence through change. The Four Causes in particular opened being to human investigation, allowing us to ask questions of itself and, in turn, of ourselves.
According to Aristotle, the question, “Why is this so?,” could be given four different, but not unrelated, answers. It is so, he averred, because this object consists of this matter (material cause), is shaped by this form (formal cause), is brought into being by this other being (efficient cause), and is moving in the direction of this end (final cause). Key to Aristotle’s philosophy, and more generally to ancient philosophy, was the background assumption that every being in the cosmos had to ‘hang together just so’ within a unified vision of being. In De Anima (On the Soul), for instance, Aristotle holds that any organic body is numerically identical with the particular soul-body or form-matter composite. And in the Nichomachean Ethics, he argues that the final end of ensouled man is eudaimonia (human flourishing or faring well) and sees no reason why this conclusion does not follow from an extended inquiry into man’s nature as a rational animal. Above all, each being strives to imitate the Unmoved Mover, an attractive and self-sufficient deity.
Quite apart from the vexed theological question of how a finite cosmos existing in a steady state could be combined with a Christian story of Genesis ex nihilo, Aristotle’s design surely had its charms, not least to medieval theologians. The Scholastic Thomas Aquinas referred to Aristotle simply and reverently as The Philosopher in his voluminous writings on theology, ethics, physics, and logic. Aquinas saw much to approve of in Aristotle’s works except that he found it necessary to amend Aristotle’s premise that humans could achieve human flourishing in this life when the latter, Aquinas observed, was only possible in the next. The goal of Aquinas’s thought was to harmonize immanence and transcendence, creation with the creative being. He did so, at least in part, through analogical reasoning, claiming that humans resembled God in key respects but surely not in all respects.
During this time, human beings “naturally longed for its divine source” (Louis Dupre) and this longing was expressed in God’s active and loving participation in being. Though not identical with His creation, God was ever present as a causal force: more like touching than like a single push. Indeed, Aquinas’s five ways to God are better understood as meditations than as rational demonstrations, for each is meant to remind the believer of how reason can be enlisted in the support of revelation. It should come as no surprise, then, that each way should end with et hoc est quod omens vocant Deum (and this is what everyone understands by God).
The synthesis between Aristotelianism and Christianity held sway so long as this world was taken to be the best and most intelligible world. The Scholastics thought so, with Aquinas being their most vocal and perceptive representative, but the nominalists, led by William of Ockham, posed a challenge that would prove unanswerable, a challenge that would open the passage to modernity and change, possibly for good, our understanding of nature as well our place within it.
Almost overnight, the nominalists overturned the intelligible conception of God as a benevolent being whose design is rational through and through, replacing it with a voluntarist God who willed this world but who could have willed some other. For would it not be a severe limitation on God’s potency to imagine that this world was the only world God could have brought into existence? And would not his potency be best expressed by holding back than, as the Neoplatonists held, by expressing himself entirely in the fullness of plenitude? The threat nominalists presented was not simply ‘intellectualist'; it was thoroughgoingly ‘vitalist’ for it became impossible to grasp God’s nature who could be acting arbitrarily, creating this world with no better reason than to show his power. If this is correct, then God is ‘opaque’ to human understanding and hence the analogy previously drawn between the Creator and creation was severed.
The conclusion to the conflict between God’s benevolence and God’s power was that God came to be seen as being ‘other than’ human being and the world began to lose its sense of being a home. Perhaps this was to be expected during a period in which humanism, ancient skepticism, and the Reformation–not to mention the Black Death–reintroduced philosophers like Montaigne to the ‘problem of the criterion': the problem, that is, of what standard can determine what we can know about some subject with absolute certainty. Suffice it to say, the natural and human world became set apart from God’s awesome divinity. When He acted, he did so from a distance, thus leaving the question of teleology up in the air.
As has often been noted, Descartes’s materialism represents a turning point in the history of the West. Descartes inherited Scholastic and nominalistic concepts of God and creation at the same time that he helped inaugurate a scientific conception of nature. Where the medieval cosmos had effected a rapprochement between nature and divinity, the scientific worldview slowly peeled man off of nature and made God irrelevant.
So Descartes stood in the midst of these raging rivers, these great conceptual dissonances, these fragmented traditions. What sense did he make of his multiple inheritances? To begin with, he claimed, following Aristotle, that reality consisted solely of substance where substance is understand as self-sufficient and thus in no need of any other thing to support its existence. According to Descartes, reality could be divided into divine substance, thinking substance, and material substance, and yet he also urged in the next breath that the only true substance was God. On the one hand, our minds were dependent for their continued existence on God, as were our bodies. On the other hand, God had become, as in the nominalist conception, ‘opaque’ to human understanding and to this extent removed from the world we experienced. In the Principles of Philosophy, Descartes confides that the divine substance “transcends the natural capacity of our wits.”
God’s disappearance from reality is no more evident than in number 28 of Principles. He writes, in what is perhaps one of the greatest understatements of the seventeenth century,
That we should not consider the final causes of created things, but only their efficient causes.
Material reality was, on this construal, to become the realm of efficient causes. A scientific understanding could trace out the cause that brought about this event, but it must remain agnostic about an entity’s reason for being. “Why is this object here? What place does it have in the order of things? Why, indeed, is there something rather nothing?” These questions would have to go unanswered, later unasked, later still forgotten.
At the same time that material reality was grasped entirely in terms of efficient causes its attributes were to be blanched of sensuous qualities. Whereas our thinking consists of willing and perception, material reality just is ‘spatial extension.’ When we analyze the concept of spatial extension, we discover only position, size, shape, and motion, all of which are in accord with the nature of efficient causality.
We are well on our way to understanding how ethics would have to run contrary to nature (see Part I). More than any other philosopher, Immanuel Kant would come to grapple with this question, embracing a disenchanted nature, striving to hold open a place for human beings beyond the material world of efficient causes, seeking to honor purposive action within the realm of human reason, and attempting to ‘re-sensualize’ nature by means of aesthetic judgment.
Before we come to Kant, however, we must pass through Locke. Descartes already takes as a given that sensuous properties are distinct from intrinsic properties; Locke makes the case even more explicitly. Whatever happened to nature’s sensuous properties like touch and taste and sight? When indeed did a red ball stop being a red ball, becoming unreal or derivative instead? In Part IV, we turn to Locke’s distinction between primary and secondary qualities…