Ancient philosophical influences - Aristotle’s causes and Prime Mover

Observation, form and purpose

Aristotle begins with the natural things we encounter and asks what makes them the kinds of things they are. Empiricism stresses experience as a starting point for knowledge. Aristotle also uses reasoning: observing growth does not by itself explain growth. The contrast with Plato concerns where enquiry begins and where form is located, rather than whether only one thinker ever reasons.

For Aristotle, a natural substance combines matter and form. Matter is what it is made from; form is its organisation or determining character. A living oak is not merely a pile of the materials found in an oak. Its organisation explains its characteristic activities. Form is immanent in the thing, rather than a separate perfect Oak elsewhere. This approach is often called hylomorphism.

Aristotle also explains change through potentiality and actuality. An acorn can develop into an oak: the potential is a capacity grounded in its nature, while the developed tree actualises it. This does not mean that every possibility will happen. Damage or unsuitable conditions may prevent development.

Teleology explains something by its end or purpose, its telos. Roots take up water for the life of the plant; a knife's shape suits cutting. The knife has a purpose given by makers and users, whereas Aristotle holds that natural things have ends grounded in their natures. He does not need to say that an acorn consciously plans its future. The disputed step is whether observed regular development establishes objective purposes in nature. A modern mechanism can explain growth without treating the outcome as a consciously intended goal.

The four causes

Aristotle's four causes are four kinds of answer to a why-question, rather than four events that must occur in chronological order. Physics II.3 and Metaphysics V.2 distinguish these explanatory roles.

The example is an application, not a quotation from Aristotle. If someone asks why the statue exists, merely saying bronze gives one relevant answer but leaves its production and purpose unexplained. Likewise, the sculptor is not its formal cause: the maker and the resulting organisation answer different questions.

Natural cases can involve overlapping roles. The mature form of an organism can also be the end towards which its development tends. Aristotle's claim is that a complete explanation may need several kinds of cause, not that every cause must be a separate person or object. An eye is explained through its materials and organisation, its development, and its activity of seeing.

A strength is explanatory breadth: asking only who made something can neglect what it is and what it does. A limitation is that a useful account of an artefact does not prove every natural process has a final cause. The evidence supporting an imposed purpose differs from the evidence supporting an intrinsic end.

The unmoved Prime Mover

Aristotle's Prime Mover explains eternal motion without itself undergoing change. In Metaphysics XII.6–7 he argues that an eternal moving order requires an eternal actual source; something merely potential could fail to act and would not sufficiently explain everlasting motion. The mover is therefore pure actuality, without unrealised potential that would require another actualiser.

This is not simply a story of a first push long ago. Aristotle understands the cosmos and its motion as eternal. The mover is unmoved, immaterial and not subject to generation or decay. Matter admits potential change, so a wholly actual mover cannot be a material body in the ordinary sense.

Its crucial connection is with the final cause. Something desirable can move another as a goal without itself being physically moved. A desired achievement explains a student's studying while the achievement is not pushing the student. Similarly, Aristotle describes the mover as moving as an object of desire and thought. The analogy explains a type of causation, not a claim that every physical object consciously studies or chooses.

In XII.9 the mover's activity is perfect thought directed towards itself: thinking of thinking. This differs from a personal God who creates the world freely from nothing, enters human history or hears prayers. Aristotle's unmoved mover should not be equated without argument with the Christian creator. Nor should we pretend his treatment is entirely simple: XII.8 considers multiple unmoved movers associated with celestial motions, within an ordered account giving the primary mover a special role.

A critic may question the inference from observed motion to this particular immaterial final cause. Even if motion needs explanation, why must its source be pure thought? Aristotle's answer depends on his wider account of actuality, perfection and cosmic order. Assessing it means testing those explanatory assumptions.

Comparing two explanations of reality

Plato's Good and Aristotle's Prime Mover both give changeable reality an unchanging ultimate explanation, but their explanatory jobs differ. The Good is the highest principle through which Forms are knowable and valuable, associated with being and truth. The Prime Mover is pure actuality and the final cause of cosmic motion. Calling both ultimate does not make them identical or establish either as a loving creator.

Plato's rationalism explains why a universal proof or moral standard exceeds particular observations. Aristotle's empiricism ties explanation to the substances and changes we encounter, avoiding a separate realm and its participation problem. Yet neither position removes every difficulty. Plato must justify access to Forms and their relationship to particulars. Aristotle must justify his movement from observed patterns to intrinsic ends and an unmoved immaterial cause.

Consider a physician learning what makes an organ healthy. Observation provides evidence of how bodies function, which favours Aristotle's starting point. Deciding what counts as normal functioning still requires concepts and reasoning; sight alone does not yield a standard. Plato rightly emphasises that understanding is more than accumulating impressions. This comparison gives a criterion: an account should explain both the evidence and the standards by which we organise it.

A justified preference for Aristotle could therefore rest on his connection between form and observable life, while rejecting an unproved cosmic telos. A justified preference for Plato could stress the stability of rational standards, while acknowledging that the cave illustrates rather than demonstrates Forms. The strongest judgement identifies which explanatory problem is solved and what additional assumptions the solution costs.