Experiment against authority
Reconstruct the experiments on the vacuum and Pascal’s rules for testing a hypothesis against the phenomena.
An original introduction. This guide accompanies the work; it is neither the complete text nor a translation.
Situating the text
The New Experiments Concerning the Vacuum appeared in 1647 and drew Pascal into a dispute with the Jesuit Étienne Noël, who denied that empty space could exist. In 1648 his brother-in-law Florin Périer carried the tube up the Puy de Dôme and found the mercury lower at the summit. The treatises on fluids and air, finished around 1654, were published by Périer in 1663. These writings record how Pascal repeated and varied Torricelli’s experiment with tubes of mercury, water and wine, and argue that the liquid column is held up not by nature’s horror of a vacuum but by the weight of the surrounding air. The posthumous treatises extend this into a general account of fluids in equilibrium, including the principle behind the hydraulic press.
Following the arguments
Burden of proof : Agreement with many phenomena never proves a hypothesis, whereas a single contrary phenomenon is enough to show that it is false. Weight of air : Because the column falls with altitude, the effects once ascribed to a horror of the vacuum follow from the pressure of the air. Equilibrium of fluids : Pressure on an enclosed liquid is transmitted in every direction, so a small force on a narrow piston can balance a large one.
Continuing the reading
Read the account of the Puy de Dôme experiment with the reply to Father Noël, then the fragment of a preface on the vacuum, which contrasts progress in the sciences with authority in theology. The New Experiments Concerning the Vacuum appeared in 1647 and drew Pascal into a dispute with the Jesuit Étienne Noël, who denied that empty space could exist. In 1648 his brother-in-law Florin Périer carried the tube up the Puy de Dôme and found the mercury lower at the summit. The treatises on fluids and air, finished around 1654, were published by Périer in 1663.
In physics a hypothesis answers to experiment, while Pascal still leaves authority its own domain in theology.
Your turn to think.
- Why does one contrary phenomenon count for more than many that agree?
- Where does Pascal draw the line between questions settled by reason and questions settled by authority?
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