How do we know a drug works?

Before you credit a treatment, list the other things that changed. Then decide which of them your inquiry controls and which it does not.

Read two of the seven conditions in the record on Ibn Sina's conditions. The first concerns the substance's condition: Ibn Sina separates a drug's power from qualities acquired through temporary heating or cooling, changes in its substance or contact with another material; the observation may reflect a temporary condition rather than the property being investigated ². The second is a simple condition: with several conditions present, a symptom may disappear because one component changes, and the result may wrongly be attributed to direct action on another component; the text therefore distinguishes direct from incidental benefit ². The record adds that this is not a description of random allocation between two groups, but an attempt to reduce ambiguity within its account of disease causation ³.

The museum's records hold no statement in which Ibn Sina says why he wrote this chapter, and they do not supply a motive for him. What they show is the setting: the study places the beginning of the Canon in Jorjan, its continuation in Rayy and its completion in Hamadan, without independently dating or locating the writing of these particular conditions ⁴. The chapter explains power through qualities such as hot and cold and through the distinction between an intrinsic property and an incidental effect ⁵, and its opening names analogy alongside experience ². The practical difficulty the conditions address, as the record puts it, is how to avoid assigning a substance a power on inadequate grounds ².

The modern study uses the conditions to discuss confounding and animal-to-human inference, comparisons that illuminate the historical questions ⁶. Britannica, for its part, warns against assuming that his contribution meant medieval physicians possessed modern research protocols ⁷. The record says that similar questions do not prove direct descent of every later drug test or establish randomization, masking and placebo comparison in the passage ⁵. The record presents both readings and does not choose between them.

It is easy to take the seven conditions for the invention of experiment or for the first clinical trial. The contribution presented is that organization of interpretive conditions within humoral medicine, not the invention of all experimentation or the birth of a modern clinical trial ⁶. "Power" here is not a modern laboratory measurement: it concerns a substance's capacity to act, explained through qualities such as hot and cold and through the distinction between an intrinsic property and an incidental effect ⁵. Hot and cold here do not mean readings on a modern thermometer ⁵.

The directly examined witness consists of printed pages 318–319, which establishes where the conditions stand in the inspected edition, not the survival of the author's personal experimental records ⁵. The study identifies a different witness, the Rome 1593 printing in the Sibbald Library, with Tibi translating the text it presents ⁸. The presence of the passage in both witnesses neither equates their pagination nor turns a later printing into the author's manuscript ^5 3. The English translation inserts a bracketed word when explaining progression, whereas the Arabic discusses power, disease strength and the weaker case; the bracketed word is not passed off as the Arabic author's own ^2 9. Ask who supplied each interpretation: Ibn Sina, the translator or the commentators.

The record says the conditions are not a description of random allocation between two groups ³, and that the modern study uses them to discuss confounding and animal-to-human inference ⁶. Take a position on whether these conditions belong to the history of controlled comparison or to something else, and answer the strongest objection to it: is the question Ibn Sina asks not the same question that a controlled comparison asks today?

• Ibn Sina's seven conditions for assessing drugs: the seven conditions one by one, with the limits of what they show.
• Ibn Sina: his life, and the researchers' readings of his affiliation.
• The Canon of Medicine: the book in which the chapter appears.