From evidence to conclusion

This lesson asks you to ask whether the evidence supports your hypothesis, where error or bias may lie, and to justify your conclusion with scientific knowledge. The museum offers two examples of how far a single piece of evidence can take you. ¹

Think of the result of a single reading: what other explanations are possible? What would have changed it if something else had changed?

Compare judging by one criterion with judging by several together. Write what each reading adds to your conclusion.

Seeing improvement after a substance is used does not, by itself, reveal what that substance actually did: Ibn Sina confronts this problem in a chapter of The Canon of Medicine setting out seven conditions for learning drug powers through experience ². Read the first two. First, 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 ³. Second, 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 ³. This is not a description of random allocation between two groups, but an attempt to reduce ambiguity within its account of disease causation ⁴.

The records read here do not quote Ibn Sina saying why he wrote this chapter, and they supply no answer for him. What they show is the frame. The Canon did not emerge into an empty medical world: Nasser, Tibi and Savage-Smith discuss al-Majusi's earlier compendium and explain classification of substances by heat, cold, moisture and dryness ⁵. The study places the beginning of the Canon in Jorjan, its continuation in Rayy and its completion in Hamadan ⁶. The record says the conditions address a practical difficulty: how to avoid assigning a substance a power on inadequate grounds ³.

A numbered list of conditions tempts readers to see a direct ancestor of a modern drug test. Similar questions do not prove direct descent of every later drug test or establish randomization, masking and placebo comparison in the passage ². Britannica itself warns against assuming that his contribution meant medieval physicians possessed modern research protocols ⁷. 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 ⁸.

The directly examined witness consists of printed pages 318–319, which establishes their location in the inspected edition, not survival of the author's personal experimental records ². The study identifies a different witness, the Rome 1593 printing in the Sibbald Library, with Tibi translating the text it presents ⁵. The Arabic pages were compared with that translation ^{2 8}. Nor is this Ibn Zuhr's animal report or another author's comparison of patient groups: the document offers interpretive conditions, not a dated experimental report with detailed outcomes ².

The modern study uses the conditions to discuss confounding and animal-to-human inference ⁸, yet the record says similar questions do not prove direct descent of every later drug test ². Take a position: is it fair to call these conditions an early training in careful reasoning about evidence, or does that read a modern idea into a text that works inside humoral medicine? Answer the strongest objection to your position: why does your position still stand?

• Ibn Sina's seven conditions: all seven conditions, with the limits of what can be said about them.
• Ibn Sina: his life and works, among them the Canon of Medicine.
• The Canon of Medicine: the book the chapter belongs to, in its five books.
• Plant-ash glass: six chemical ratios, and Schibille's warning that no single criterion suffices.

Read the records on Ibn Sina's seven conditions and plant-ash glass. Choose a result from an experiment you ran and write what supports it and what could weaken it.