The concept of actualism is a difficult one, but it is one of Karl Barth's principal motifs. George Hunsinger, the Director of Princeton Seminary's Center for Barth Studies, provides a lengthy explanation of this Barthian concept which warrants quotation in full:
Actualism is the most distinctive and perhaps the most difficult of the motifs [in Barth's theology]. It is present whenever Barth speaks, as he constantly does, in the language of occurrence, happening, event, history, decision. At the most general level it means that he thinks primarily in terms of events and relationships rather than monadic or self-contained substances. So pervasive is this motif that Barth's whole theology might well be described as a theology of active relations. God and humanity are both defined in fundamentally actualistic terms.
For example, when Barth wants to describe the living God in a technical way, he says that God's being is always a being in act. Negatively, this means that God's being cannot be described apart from the basic act in which God lives. Any attempt to define God in static or inactive terms, as is customary in certain theologies and philosophies, is therefore to be rejected. Positively, the description means that God lives in a set of active relations. The being of God in act is a being in love and freedom. God, who does not need us to be the living God, is perfectly complete without us. For God is alive in the active relations of love and freedom which constitute God's being in and for itself. These are the active relations of God's trinitarian self-differentiation. From all eternity the Father loves the Son, and the Son loves the Father, in the unity of the Holy Spirit. God is free to be God, to constitute the divine being, in this distinctively trinitarian way. God is the Lord, the acting subject, of this self-constituting, mysterious event. Although there is much more to it than this, the basic point of the actualism can already be suggested, as far as the doctrine of God is concerned. Actualism emphasizes the sovereign activity of God in patterns of love and freedom--not only in God's self relationship, but also in relationship to others (II/1, 257-321).
As far as human beings are concerned, the basic point is to understand them strictly with regard to the pattern of God's sovereign activity. Negatively, this means that we human beings have no ahistorical relationship to God, and that we also have no capacity in and of ourselves to enter into fellowship with God. An ahistorical relationship would be a denial of God's activity, and an innate capacity for fellowship would be a denial of God's sovereignty. Positively, therefore, our relationship to God must be understood in active, historical terms, and it must be a relationship given to us strictly from the outside. Our active relationship to God is a history of love and freedom; we are capable of it not because it stands at our disposal, but because we who stand at God's disposal are given it. Our relationship to God is therefore an event. It is not possessed once and for all, but is continually established anew by the ongoing activity of grace. Paradoxically, however although befalling us from the outside and exceeding our creaturely capacities, the event of grace deeply enhances rather than diminishes us. It draws us beyond ourselves into a relationship of communion, of love and freedom, with God. The sovereignty of grace is thus not the negation, but the condition for the possibility, of human spontaneity and fulfillment. God's sovereignty in our lives is enacted as God establishes us with a history of love and freedom.
Barth's theology of active relations is therefore a theology which stresses the sovereignty of grace, the incapacity of the creature, and the miraculous history whereby grace grants what the creature lacks for the sake of love and freedom. This pattern appears again and again in the Church Dogmatics [of Barth]. The church, the inspiration of scripture, faith, and all other creaturely realities in their relationship to god are always understood as events. They are not self-initiating and self-sustaining. They are not grounded in a neutral, ahistorical, or ontological relationship to God independent of the event of grace. Nor are they actualizations of certain ontologically given creaturely capacities. Rather, they have not only their being but also their possibility only as they are continually established anew according to the divine good pleasure. They have their being only in act--in the act of God which elicits from the creature the otherwise impossible act of free response. God is thus the Lord--not only of the mysterious event which constitutes the divine being, but also of the mysterious event which constitutes our being in relation to God.
This point may be drawn to a close with a simple but telling example. Barth's actualistic mode of thought enables him to explain why it is a mistake to reverse the biblical dictum that "God is love." (1 John 4:8, 16) so that instead it would say "Love is God" as though God could be equated with an abstract concept of love in general. As Barth carefully shows on exegetical grounds, "God is love" is a concise way of describing God's activity. It means that "God acts in a loving way." The statement cannot be reversed, because "God" refers to an acting subject, and "love" to the quality of God's activity. (Or more precisely, it could be reversed only one were to take this sense into account.) This example illustrates how Barth wants his actualistic sensibility to arise from and point back to scripture. The actualism is considered valid only insofar as it can illuminate scripture patters of thought (I/2, 374; II/1, 275, IV/2, 756)
George Hunsinger, How to Read Karl Barth: The Shape of His Theology (Oxford: Oxford University Press, 1991), 30-32 (emphasis added).
Occasionalism is a related concept to actualism. Occasionalism, as described by the Protestant ethicist James M. Gustafson, is "a view of moral action that emphasizes the uniqueness of each moment of serious moral choice in contrast to a view that emphasizes the persistent, perduring order of moral life and the continuities of human experience." In the context of morality, occasionalism results in a subjective morality, where "the moral life is without the props of principles of natural law, which have provided a basis for great objective certitude and for moral absolutes universally valid across time to all who share a common human nature." Gustafson, Protestant and Roman Catholic Ethics: Prospects for Rapprochement (Chicago: University of Chichago Press, 1978), 71, 72 (quoted in Grabill, 204-05, n. 17.)
The problem with Barth's actualism and occasionalism is that it results in a lack of balance in his thought, a problem resulting from his overemphasis of act, and an underemphasis of being. There is a decided overemphasis of freedom and sovereignty of God, and an underemphasis of law and reason. It is the doctrine of a man who focuses on trees, and so is blind to the beauties of the forest; who focuses on the notes, and so fails to hear the song; who reads specific judgments, but is unable to distill therefrom the rule or law; it is the limitation of a child who mouths words using phonics, but misses the thought in the sentence, the paragraph, or the book. To such a man, God's relationship with creation and with man is, as it were, a series of discrete points instead of a continuum.
Perhaps the best analogy for understanding Barth and for revealing the defect of his actualism and occasionalism and the cul de sac to which they lead is to compare his thought to music. Under Barth's actualism and occasionalism, our relationship with God is one of infinite independent notes, each one free and sovereign. And yet there is no melody, there is no underlying music that we may discern. (Any melody suggests a self-limiting plan, an ordering of notes following a motif, phrase, or theme as part of a greater melody, which is not consonant with Barth's emphasis on freedom and sovereignty of God.) So our relationship with God is a series of ultimately arbitrary and discrete notes: events, acts, occasions, each one independent and not part of a greater whole. It is as if Barth advances a theory of morality which is analogous to the chance music of John Cage--the throw of dice, and not any plan, determines the next note. There is no relationship, no greater melody, that ties one note to the other.
Ultimately, Barth's overemphasis on act over being, on freedom and sovereignty over law, leads to a moral deafness. One becomes deaf to the whole moral song when one insists that our relationship with God is not a melodious relationship, where there are not only discrete or arbitrary notes, but there also is an overarching melody, a complex and orderly panoply of motif, phrases, and themes in a unified whole. For Barth, God, and our relationship with God and his relationship with us, is a series of notes, and not one of melody. And where there is no overarching melody, there is no rule or law to be found; where there is no rule or law, there can be no discernible melody. For Barth's theological tin ear, the statement "God is Law Itself," as found in the Mirror of Saxons, would be jarring, when, in fact, for the trained ear, it is nothing but the most beautiful of melodies.
Indeed, in the moral life of man there is an underlying dual melody. There is a biphony in the moral song that God plays out in his creation naturally and in his redemption of that world in Christ supernaturally. Barth could not, would not hear it. That underlying melody is the Eternal Law. Played out in our world, and in the inner ear of our heart, this underlying melody is heard in the voice of the Natural Law. Played out in revelation, and in God's Word, the underlying melody is heard in the Divine Law. This dual melody is composed by God himself in the act of Creation and the act of Revelation. It is through this lovely melody that God woos us. It is through this melody by which God, as a man might his wife, beckons us to dance with him. It is in the harmonies and rhythm of this melody that we dance with God in the pas de deux that is the moral life. A dance that is ever and eternally in step with the dual strains of the Natural Law and Divine Law, which together harmonize into the one eternal and echanting melody of the Eternal Law.