The "causal adequacy principle" (CAP) is a philosophical claim made by René Descartes

René Descartes

René Descartes ; was a French philosopher and writer who spent most of his adult life in the Dutch Republic. He has been dubbed the 'Father of Modern Philosophy', and much subsequent Western philosophy is a response to his writings, which are studied closely to this day...

 that the cause of an object must contain at least as much reality as the object itself, whether formally or eminently.

Descartes defends this principle by quoting Roman philosopher Lucretius

Lucretius

Titus Lucretius Carus was a Roman poet and philosopher. His only known work is an epic philosophical poem laying out the beliefs of Epicureanism, De rerum natura, translated into English as On the Nature of Things or "On the Nature of the Universe".Virtually no details have come down concerning...

:
"Ex nihilo nihil fit", meaning "Nothing comes from nothing". —

In his meditations, Descartes uses the CAP, to support his trademark argument

Trademark argument

The trademark argument is an a priori argument for the existence of God developed by French philosopher and mathematician, René Descartes. The argument, though similar to the ontological argument, differs in some respects, since it seeks to prove the existence of God through the causal adequacy...

 for the existence of God. Descartes' assertions were disputed by Thomas Hobbes

Thomas Hobbes

Thomas Hobbes of Malmesbury , in some older texts Thomas Hobbs of Malmsbury, was an English philosopher, best known today for his work on political philosophy...

 in his "Third Set of Objections" published in 1641. . Amongst other contemporary objections, CAP comes under difficulties when it comes to the idea of creation and beginning. If one accepts CAP one has to necessarily accept that there is no beginning (thus no end) in anything. Such an objection, although controversial, is justified because if God is supposed to be the creator of all, CAP would argue that he is caused by something as big or greater. Such a claim is not logically possible if one accepts that God is in fact perfection incarnate. The same goes to there having been a Big Bang. CAP would again argue that a Bigger Big Bang must have caused the one we know as the beginner of our universe. This causes what is known in Philosophical circles as Infinite Regress.

Jargon explained

• A "cause" is that which brings something into effect.

• If an item has the quality X formally, it has it in the literal or strict sense.
• If an item has the quality X eminently, it has it in a higher or grander form.

CAP in practice

To demonstrate this, a person can possess money formally by holding it on their person, or by storing it in a bank account. Similarly, a person can eminently possess money by owning assets that could readily be exchanged for it.

Descartes offers two explanations of his own:

• Heat cannot be produced in an object which was not previously hot, except by something of at least the same order of perfection as heat.

• A stone, for example, which previously did not exist, cannot begin to exist unless it is produced by something which contains, either formally or eminently everything to be found in the stone.

Descartes goes on to claim that the CAP not only applies to stones, but also the realm of ideas, and the features that are seen as part of the objective reality of an idea.