Yet their detractors replied: one unit out of ten is not ten; a single piece of a dome or a house is neither a dome nor a house; and a part of a human being is not itself a human. Hence thinkers such as al-Āmidī and al-Abharī—perplexed by the impossibility of an infinite regress of efficient causes—contended that each individual cause may indeed be contingent while the aggregate is not. Thus these inquiries, which touch the very foundations of religion and knowledge, became confused even among the leading philosophers and theologians.

The decisive word on the matter is this: when an individual element is joined to others, the union either produces something whose ruling differs from that of the individuals, or it does not. If the union does not bring about a reality that diverges from the ruling of the parts, the whole shares the same ruling as the parts. But if the union does produce something that differs from the ruling of the parts, the ruling of the whole need not match that of its constituents.

An example of the first case is two nonexistent things: putting one with the other does not lift them out of non-existence. In the same way, combining one necessary being with another, one contingent thing with another, or one existent with another existent does not alter their respective statuses—unless the two are mutually contradictory.

An example of the second case is the limbs of a human or any other animal, the components of a house, a building, a city, and the like: when these parts come together, the resultant whole becomes an animal, a house, or a city. Similarly, individual units, once gathered, become ten or a thousand, and every other composite acquires through aggregation a structure not possessed by its parts taken singly—and the same holds for the segments of a lengthy whole.