What can reason establish about causation?

What the bell tells you

Imagine a school bell that rings every afternoon, just before children pour into the street. Soon you expect the children whenever you hear the bell. But what exactly have you learned? That the two events regularly occur together? That one produces the other? That the second could not possibly fail to follow the first?

These are different claims. Perhaps the bell tells teachers to dismiss their classes; perhaps the teachers follow a clock and the bell merely coincides with dismissal. Further inquiry could tell these explanations apart. Knowing what to expect is a beginning, but explaining why it happens asks more of us.

Al-Ghazali’s question

Al-Ghazali was a Muslim theologian and legal scholar from Tus, in present-day Iran, who taught in Baghdad and died in 1111; his work also drew deeply on Sufi traditions of spiritual practice. He engaged both with kalam, reasoned theological inquiry, and with falsafa, the philosophical tradition shaped by Greek learning in Arabic. The two traditions had different commitments, but arguments passed between them. [3]

In discussion 17 of The Incoherence of the Philosophers, he challenges arguments that would rule out prophetic miracles. The previous lesson showed how a thing could be contingent in itself yet necessary through its complete cause. Here the question is what that causal necessity amounts to: must fire burn what it touches?

Cotton, fire and the burden of proof

Al-Ghazali considers cotton touching fire. The cotton burns, and he asks what entitles us to say that the fire itself produces the burning and cannot fail to do so when the cotton is in a condition to burn. Seeing burning occur alongside contact does not, by itself, show that fire is its sole cause. [1]

He attributes the production of burning to God, acting directly or through intermediaries, so that God could create the contact without creating the combustion. This makes room for the possibility of miracles. Yet the observation argument alone has not proved that God acts in this way. It challenges an opponent’s explanation; establishing the alternative requires more.

So the precise target is stronger than “cotton usually burns.” It is the claim that the connection cannot be otherwise, together with a claim about what brings the effect about. Causal necessity concerns whether, given the relevant cause and conditions, the effect must follow, and the question is what justifies that “must.” [5]

Possibility without everyday chaos

An objector presses an alarming consequence. If familiar connections can fail, how can we know what we will find when we get home? The book we left there might have become something entirely different.

Al-Ghazali replies that what is possible need not happen: God can sustain the regular course of events and create our knowledge of what will happen. The answer draws on his account of God, and a critic can still ask what supports the assurance it offers. [1]

The chapter also explores a second answer: grant that things have natural powers, but allow that God can alter the conditions or bring about changes at an unfamiliar speed. Scholars disagree about whether such passages express his own preferred account or argue from an opponent’s assumptions. Either way, they stop us from reducing the whole chapter to a single denial of natural causation. [3]

Nor does divine power make contradictions true: al-Ghazali explicitly excludes affirming and denying the same thing at the same time. His challenge uses reasoning to contest what the philosophers claim to have demonstrated. [1]

Averroes defends natural powers

Ibn Rushd, known in Latin as Averroes, belonged to a later generation. Born in Córdoba in 1126, he worked as a jurist and physician in the world of al-Andalus and the North African Almohad rulers. His Incoherence of the Incoherence answers al-Ghazali in writing, not in a face-to-face debate. [4]

Averroes argues that things have distinctive natures and powers, and that understanding why something happens involves knowing these causes. Remove every connection between a thing’s nature and what it does, and we threaten the very explanatory knowledge we were trying to understand. [2]

His reply includes an important qualification. Fire need not burn every object brought near it, because an obstacle may prevent its power from taking effect. A failure to burn therefore need not show that fire lacks a burning power; we must investigate the conditions. In his closing response he accepts that an impediment could prevent an expected effect, while disputing other parts of al-Ghazali’s account. [2]

Where the disagreement remains

Averroes’s qualification matters. “Fire is nearby” falls short of a full account of the conditions for burning, just as the school bell cannot explain dismissal without the people and arrangements that make it effective.

Adding conditions, though, does not by itself settle the deeper challenge. How do we know that our observations disclose powers rooted in the natures of things? Averroes treats our knowledge of nature as evidence that we grasp real causes; al-Ghazali questions what the observations establish. Someone who accepts reliable predictions but doubts that we know things’ causal powers can still challenge Averroes’s starting point. [5]

We should also distinguish explaining a regular occurrence from proving that no divine exception is possible. Each author’s understanding of divine action shapes the disagreement, yet both are reasoning about how far knowledge reaches and what grounds it.

A continuing conversation

A book called Incoherence can sound like the end of a conversation, but this dispute became part of a continuing one. Al-Ghazali adopted philosophical tools even as he criticized particular teachings, and logical and metaphysical inquiry continued within later theology. [3]

Averroes’s works, too, had readers in Muslim intellectual settings after his death; specialist research traces their use by Ibn Tumlūs in medicine and logic, among other examples. A refutation, or even a philosopher’s troubled political career, is no evidence that a whole intellectual tradition stopped thinking. [4]

Try the distinction

Farah says: “The school bell rang every day before dismissal. That proves the bell must release the children. If tomorrow it rings and nobody leaves, we will know that causes do not exist.”

Identify both leaps. How could al-Ghazali’s challenge and Averroes’s reply help her improve the argument?

Read a possible response

Farah first moves from a repeated sequence to a necessary causal connection. Al-Ghazali’s challenge to inferring necessity from observation shows what she is missing: evidence about how the bell affects dismissal and which other conditions matter. Her second leap goes from one failed expectation to denying all causes, and here Averroes would direct her attention to powers and impediments. Perhaps the bell works, but the teachers keep the children inside; that explanation would still need evidence. Neither correction proves or disproves divine action, and the exercise does not ask you to choose a religious position.

Carry this forward

Questioning how certain an explanation is can send inquiry in a new direction. In How can we speak about God?, Maimonides asks how familiar words can guide our thinking about God without turning God into a larger version of ourselves.

Sources and limits

[1] Al-Ghazali, The Incoherence of the Philosophers, discussion 17, translated by Sabih Ahmad Kamali, Pakistan Philosophical Congress, 1958; second impression 1963, for al-Ghazali’s challenge and his two answers. The complete Problem XVII web text was read, and printed pp. 185–196 were checked in the scan, together with the title, copyright, translator’s preface and the note to p. 191 on p. 254. The pages cover:

• The opening and the first position: pp. 185–187.
• The two answers: pp. 188–193.
• Impossibility: pp. 193–196.

The web header claims that the translation passed through Urdu; the inspected print credits do not establish that claim.

[2] Averroes, The Incoherence of the Incoherence, translated from Arabic by Simon van den Bergh, 1954, Natural Sciences, First Discussion, for Averroes’s defense of natural powers. Read: the opening exchange and the complete first reply, beginning “To deny the existence,” and the complete closing reply, beginning “When Ghazali saw that,” with selected surrounding exchanges. The e-text has damaged punctuation and detached note markers, and neither the full notes volume nor the Arabic edition was read. Richardson locates the first reply at English pp. 318–319; those print pages were not inspected here.

[3] Frank Griffel, “al-Ghazali”, Stanford Encyclopedia of Philosophy (SEP), revised 15 January 2026, for al-Ghazali’s setting, the interpretation of his answers and the later course of the debate. The introduction and §§1, 7.2 and 7.4 were read complete. The different interpretations of the second answer remain open.

[4] Fouad Ben Ahmed and Robert Pasnau, “Ibn Rushd [Averroes]”, SEP, revised 20 August 2025, for Averroes’s setting and his reception in Arabic; §§1.1 and 9.1 were read complete. The later works discussed there were not read directly.

[5] Kara Richardson, “Causation in Arabic and Islamic Thought”, SEP, revised 15 August 2025, for the distinctions between necessary connection, evidential support and impediments; §§3.3.1–3.3.2 and 4.2–4.3 were read complete.

The school bell, Farah and the response are original teaching material. No whole book, Arabic collation or complete second primary translation was read. Kamali acknowledges using van den Bergh’s work, so these English witnesses are not treated as independent. The lesson has not undergone independent specialist or learner review, and its reading time has not been measured. Neither thinker represents every Muslim view, and understanding their arguments does not require sharing their faith.