Causality: Aristotle vs. Modern Physics

Hello! Welcome to the next lesson in our exploration of contemporary arguments for a first cause.

In our last session, we examined the modern defenses of core Aristotelian concepts like actuality/potentiality and hylomorphism, showing how they stand up to objections from modern philosophy and science. We established that these concepts are more robust than often assumed.

Today, we drill down into what is arguably the most critical and frequently misunderstood concept in the entire Aristotelian argument: the nature of causality itself. Our goal is to distinguish between Aristotelian hierarchical/sustaining causality and the event-causality model used in modern physics. Understanding this distinction is the key to seeing why many common objections to the argument from motion, particularly those concerning an infinite past, miss the mark entirely.

Given your background in econometrics and time series analysis, you are already intimately familiar with one of these models. Models like $Y_t=f(Y_{t-1},X_t,\dots )$, where an outcome at one point in time is explained by events at prior points in time, are a perfect expression of the event-causality model. Today, we will formalize this model and contrast it with the very different type of causality Aristotle had in mind.

1. The Event-Causality Model: Linear, Accidental, and Horizontal

The model of causality most familiar to us today is one of sequential events. One event happens, which then triggers another, and so on, like a series of falling dominoes.

In this model:

• Causes precede their effects in time.
• The causal series is a temporal sequence.
• Once a cause has produced its effect, it can cease to exist without the effect disappearing or losing its own causal power. A person builds a house, and the house remains standing long after the builder has left.

Philosophers use several names for this model, which are helpful to know:

• Linear or Temporal Series: This emphasizes that the chain unfolds along the axis of time.
• Horizontal Causality: This visualizes the chain stretching out "horizontally" across time.
• Accidentally Ordered Series (per accidens): This is the formal scholastic term. It doesn't mean "random," but rather that the connection between the members is not essential for their ongoing causal power. A grandfather can beget a father, who begets a son. The son's ability to have children later does not depend on the grandfather still being alive.

To solidify these concepts, let's turn to a clear overview.

2. The Sustaining-Causality Model: Hierarchical, Essential, and Vertical

Aristotle's primary focus, and the foundation of his argument for an unmoved mover, is a different kind of causal series. This model is not about a sequence of events in time, but about a simultaneous hierarchy of dependence.

Think of a hand pushing a stick which, in turn, pushes a stone.

• The hand, stick, and stone are all moving at the same time. The cause and effect are simultaneous.
• The stick's power to move the stone is entirely derived from the hand. It has no power of its own to do this.
• If the hand stops, the stick immediately stops, and the stone stops. The causal power of the higher members must be continuously exercised for the lower members to act.

This is the model of sustaining causality. The names for this model contrast directly with the first:

• Hierarchical Series: Emphasizes the ranking of dependence, from primary to derivative causes.
• Vertical Causality: Visualizes the causal influence flowing "down" from a higher source of power to a lower recipient, all at the same instant.
• Essentially Ordered Series (per se): The formal scholastic term. The ordering is "essential" because the very ability of a member to act as a cause is dependent on its connection to the member above it in the hierarchy.

Let's watch a segment where Edward Feser explains this crucial distinction and its implications.

Now, let's return to the same reading to see the formal definition of this second type of series.

3. Why the Distinction is Crucial: The Infinite Regress

The payoff for making this sharp distinction comes when we consider the problem of an infinite regress.

• An accidentally ordered (linear/temporal) series can, at least in principle, regress infinitely into the past. Aristotle himself believed the universe was eternal and had no beginning. An infinite chain of past events (father after father, etc.) is not what his argument rules out. Critics who claim that "we now know the universe had a beginning (the Big Bang), so Aristotle was wrong" are attacking a straw man; they are thinking of the wrong kind of causal series.

• An essentially ordered (hierarchical/simultaneous) series, however, cannot be infinite. Because each member (like the stick) has only derived causal power, the entire chain of dependency must terminate here and now in something that has its causal power in a primary, non-derived, "built-in" way. Without a first member of the hierarchy—an engine for the train, a hand for the stick, a primary supporter for the chain of people hanging from the cliff—none of the subsequent members would have any causal power to derive. The entire system would be inert.

The Aristotelian argument, therefore, is not about finding the first domino in a temporal chain. It is an argument for a simultaneously existing, sustaining cause that grounds the reality of any and all change happening right now.

Summary Table

To consolidate these two concepts, here is a summary table:

Conclusion

You can now see the profound difference between these two models of causation. The event-causality model describes chains of events across time, which is the primary focus of modern physics and fields like econometrics. The hierarchical model, by contrast, describes the structure of dependence and sustenance at any given moment.

Key Takeaways:

• Event-causality is a temporal, linear chain of causes (e.g., dominoes). This is also called an accidentally ordered or horizontal series.
• Hierarchical causality is a simultaneous, dependent structure of causes (e.g., hand-stick-stone). This is also called an essentially ordered or vertical series.
• The Aristotelian argument against infinite regress applies only to the hierarchical series, arguing for the necessity of a first, non-dependent, sustaining cause that is active right now.

By grasping this distinction, you have bypassed one of the most common and fundamental misunderstandings of the argument for a First Mover.

In our next lesson, we will put this understanding to the test. We will ask: Does the principle of inertia in classical mechanics eliminate the need for a concurrent sustaining cause of motion? Now that we know what a sustaining cause is, we are equipped to properly evaluate this classic scientific objection.