Argument from Change

Overview

The Argument from Change (also known as the argument from motion or, in one classic form, Aquinas’s First Way) is a metaphysical argument that moves from the reality of change in the world to the existence of a first unmoved mover. Here, change is typically understood broadly as the transition from potentiality to actuality, not just spatial motion.

In its traditional versions, the argument is a kind of cosmological argument: it appeals to very general features of the world—specifically, that things come to be, pass away, move, warm up, cool down, and so on—and claims that such processes cannot be fully explained unless there is a fundamental cause of change that is itself unchanging.

Classical Formulations

Aristotle

The roots of the argument lie in Aristotle’s account of motion and causation, especially in Physics and Metaphysics. Aristotle defines motion (kinesis) as the actualization of a potential as such. For example, a cold object has the potential to be hot; when it is being heated, that potential is being actualized by something already hot.

Aristotle’s reasoning can be summarized as:

1. There is motion (change) in the world.
   We observe things altering in quality, place, and state.

2. Whatever is moved is moved by another.
   A thing cannot be while it is purely potential; to be actualized, it must be acted on by something already actual in the relevant respect.

3. An essentially ordered series of movers cannot regress infinitely.
   A series where each member’s power to cause motion depends here and now on a prior cause (e.g., hand–stick–stone) cannot be infinite, because then there would be no first source of the motion currently occurring.

4. Therefore, there must be a first unmoved mover.
   This mover causes motion without itself being moved. For Aristotle, this first mover is pure actuality and is identified with a divine intellect.

Aristotle’s concern was partly to explain eternal cosmic motion (such as the rotation of the heavens) in a way that does not rely on an infinite explanatory regress.

Aquinas

Thomas Aquinas adapts Aristotle’s idea in Summa Theologiae (I, q.2, a.3) as his First Way of demonstrating God’s existence. Aquinas emphasizes the distinction between potentiality and actuality and the impossibility of an infinite regress in an essentially ordered (per se) series of causes of change.

A typical Thomistic formulation:

1. Things in the world are in motion (undergoing change).
2. Nothing can be reduced from potentiality to actuality except by something already actual in that respect.
3. Nothing can move itself from pure potentiality to actuality in the same respect and in the same way.
4. Therefore, any instance of change involves an essentially ordered series of actualizers.
5. Such a series cannot regress infinitely, since the causality of each member depends here-and-now on a first cause.
6. Hence there must be a first unmoved mover, itself pure actuality and the ultimate source of all change.

Aquinas explicitly identifies this first unmoved mover with God—conceived as a necessary, unchanging, and purely actual being.

Key Criticisms and Responses

Criticisms

1. Challenge to the potentiality–actuality framework
   Critics influenced by early modern philosophy or contemporary science question whether the Aristotelian metaphysical scheme is necessary or accurate. They argue that talk of “potentials” and “actualities” is either obsolete or can be replaced by modern physical concepts (such as dispositional properties or probabilistic states) without implying an unmoved mover.

2. Self-motion and internal causation
   Some object that many things appear to move or change themselves—for example, living organisms or subatomic particles. If systems can have internal sources of change, the premise that “whatever is moved is moved by another” may appear dubious or at least in need of substantial qualification.

3. Infinite regress and its alleged impossibility
   The claim that an essentially ordered causal series cannot be infinitely long is contested. Some philosophers argue that there is no logical contradiction in an infinite hierarchy of causes existing simultaneously, each depending on earlier ones without a first member.

4. Relevance of modern physics
   Developments in classical mechanics, relativity, and quantum theory lead some to question whether the Aristotelian-Aquinian notion of motion and causation still applies. For example:

   • Inertia in Newtonian and relativistic physics suggests that objects in motion need no continuous external mover to remain in motion.
   • Quantum events are sometimes interpreted as indeterministic or as lacking classical causes, which may undermine the universality of the causal principles used in the argument.

5. From unmoved mover to God
   Even if a first unmoved mover is granted, some critics contend that it does not follow that this being has the full range of attributes associated with the God of classical theism (omniscience, omnipotence, moral perfection, personal agency). Additional arguments are required to bridge that gap.

Responses and Contemporary Defenses

1. Reinterpreting “motion” and explanatory order
   Defenders distinguish between:

   • Temporal series of causes (stretching backward in time), where an infinite regress may be possible; and
   • Essentially ordered series, where each member’s current efficacy depends on a prior actualizer.

   They argue that the Argument from Change concerns the latter: the present, hierarchical dependence of change on a primary source, not a temporal beginning.

2. Rehabilitation of Aristotelian metaphysics
   Some contemporary philosophers (often called neo-Aristotelians or Thomists) maintain that the potentiality–actuality distinction is still needed to make sense of:

   • Persistence and change
   • Dispositions and powers
   • Causal asymmetry

   On this view, modern physics describes how change occurs within the framework of space, time, and fields, but does not address the deeper metaphysical question of why there is any actualization of potentialities at all.

3. Compatibility with physics
   Proponents contend that the argument does not depend on outdated empirical claims (like pre-Newtonian mechanics) but on more abstract claims about metaphysical dependence. They argue that even in a quantum world, events involve transitions from possible states to actual ones, and such transitions still raise the question of why there is any actuality rather than only potentiality.

4. From unmoved mover to a rich theistic conception
   Defenders typically supplement the Argument from Change with further reasoning to show that a purely actual, unchanging source of all change would also be:

   • Necessary (cannot fail to exist)
   • Simple (not composed of parts)
   • Perfect (lacking unrealized potential)
   • Intelligent and volitional (as the source of ordered, goal-directed processes)

   Whether these additional steps succeed remains a matter of ongoing debate.

Overall, the Argument from Change remains a central topic in the philosophy of religion and metaphysics. Its status is widely regarded as controversial: influential and sophisticated in its strongest historical and contemporary forms, yet subject to substantial and persistent philosophical criticism.