Causation causation, that relation which we suppose to exist between events, is perceived only through constant conjunction. One observes that certain objects or actions are invariably followed by others; the flame touches the paper, and the paper is consumed; the billiard ball strikes another, and the second moves. In all instances of the first event, the second follows. This regularity of sequence is all that experience reveals. We do not perceive any hidden force, necessary connection, or intrinsic power that binds the first to the second. The mind, accustomed to this succession, forms an expectation that the same event will follow the same precedent. Yet this expectation is founded not upon reason, but upon custom. It is observed that when a stone is thrown into still water, ripples appear in succession. But we do not see the stone compel the water to move. We see only the motion of the stone, then the motion of the water. We infer a relation, but we do not apprehend a necessity. When smoke arises from a fire, we say the fire causes the smoke. But what is the impression from which this idea of causation is derived? It is not the fire itself, nor the smoke itself, but the uniformity of their conjunction. We have no idea of any necessary connexion between causes and effects; we only observe their constant conjunction. One may consider the movement of a clock’s hands. The hour hand moves as the minute hand completes its cycle. The two motions are regularly associated. But we cannot say the minute hand causes the hour hand to move. We see only their succession. The mechanism within the clock, though unseen, is not perceived by the senses. It is a supposition added by the mind, not an impression received from the object. We observe the sequence; we do not observe the power. When a child touches a hot stove, it withdraws its hand. From this single instance, the child does not conclude that heat necessarily burns. But after several such experiences, the child anticipates pain upon approaching fire. This anticipation is not the result of logical deduction. It is the effect of repeated observation, which implants in the mind a habit of expecting the usual consequence. The same principle governs the adult’s belief in the rising of the sun, the falling of objects, or the decay of fruit. All such beliefs arise from custom, not from any demonstrable necessity. It is possible for events to be constantly conjoined without being causally related. The clock strikes noon, and the baker opens his shop. This succession is regular, yet we do not conclude that the clock causes the shop to open. The association is coincidental, though constant. We judge causal relations by the regularity of their recurrence, and by our inability to conceive the effect without the cause. But this inability is not a property of the objects themselves; it is a property of the mind’s habit. We may press further. Suppose one had never seen fire before, and encountered it for the first time. Would one know, merely by observing the flame, that it would burn? No. The idea of burning arises only after experience. The same applies to gravity, magnetism, electricity. We know the effects, and we know their uniform sequence. But the power by which one event produces another? That power is never seen. It is not an object of sensation. It is an idea constructed by the mind after repeated impressions. Thus, causation is not an inherent feature of the world as it exists independently of the mind. It is a mental construction, drawn from the uniformity of experience. We believe it to be real because it is universal in our experience. But universality is not necessity. Custom, not reason, leads us to suppose that tomorrow’s sun will rise, that bread will nourish, that water will quench thirst. One may ask: if all our knowledge of causation rests on habit, can we ever be certain that the future will resemble the past? And if not, upon what foundation does science itself rest? [role=marginalia, type=extension, author="a.dewey", status="adjunct", year="2026", length="44", targets="entry:causation", scope="local"] Yet we mistake the uniformity of observed sequences for metaphysical necessity—confusing epistemic habit with ontological binding. Causation, as Hume reveals, is a psychological projection onto nature’s syntax; the “force” we impute is the mind’s echo of its own expectations, not the world’s inner logic. [role=marginalia, type=clarification, author="a.turing", status="adjunct", year="2026", length="44", targets="entry:causation", scope="local"] We mistake temporal succession for causal necessity—yet no observation reveals the “glue” between events. Custom conditions expectation, not knowledge. The ripples follow the stone, yes—but the necessity resides not in nature, but in the mind’s habit of projecting pattern where only sequence is given. [role=marginalia, type=objection, author="Reviewer", status="adjunct", year="2026", length="42", targets="entry:causation", scope="local"]