Leviathan and The Air-Pump - Chapter II: Seeing and Believing: The Experimental Production of Pneumatic Facts

Chapter II: Seeing and Believing: The Experimental Production of Pneumatic Facts

Chapter two outlines Boyle's theory of knowledge production, which revolves around the creation of the "matter of fact". This refers to an experimentally generated piece of knowledge separate from a universal theory and that was based on probability. This is in direct opposition to Hobbes (discussed in chapter 3), who required "absolute certainty" based on "logic and geometry" to consider a phenomenon a fact. In the eyes of Boyle and his colleagues, the abandonment of absolute certainty was not "a regrettable retreat from more ambitious goals; it was celebrated as a wise rejection of a failed project". Thus, because "matters of fact" did not have to be absolute, universal assent was not necessary for the production of knowledge. Boyle made use of three knowledge-producing technologies in order to produce knowledge: "a material technology embedded in the construction and operation of the air-pump; a literary technology by means of which the phenomena produced by the pump were made known to those who were not direct witnesses; and a social technology that incorporated the conventions that experimental philosophers should use in dealing with each other and considering knowledge-claims".

Importantly, Shapin and Schaffer give a description of the "material technology," the air-pump itself, essentially a suction pump attached to a replaceable glass bulb. When the pump was set in motion, the air would be evacuated from the glass bulb thus creating what we now consider to be a vacuum, but what for contemporaries was a space of great debate (explained below). However, the integrity of the pump was far from perfect and this leaking is central to the arguments both for and against experimentalism. Shapin and Schaffer assert that three important points should be taken into account when considering the pump itself: "(1) that both the engine's integrity and its limited leakage were important resources for Boyle in validating his pneumatic finding and their proper interpretation; (2) that the physical integrity of the machine was vital to the perceived integrity of the knowledge the machine helped to produce; and (3) that the lack of its physical integrity was a strategy used by critics, particularly Hobbes, to deconstruct Boyle's claims and to substitute alternative accounts".

The arguments about experimentally generated knowledge revolve around two of Boyle's experiments. The first experiment is the Torricellian apparatus placed within the exhausted receiver (the bulb). The result is that the liquid in the inverted tube of the Torricellian apparatus falls, but not to the level of the liquid in the dish at the base of the inverted tube. For Boyle, the water level fell because the air was being evacuated from the bulb and thus its spring and weight were no longer acting on the liquid around the base of the tube holding the liquid in the inverted tube up. The fact that the water did not fall completely to the bottom of the tube was explained (for Boyle) by the existence of air in the bulb that occurred due to leakage. However Boyle was careful not to commit to saying that a vacuum existed in the bulb; he stated only that when air was sucked out of the bulb the level of the liquid in the inverted tube fell - this was the nature of a matter of fact. The second experiment was based on the theory of cohesion - that "two smooth bodies, such as marble or glass discs, can be made spontaneously to cohere when pressed against each other". Boyle's idea was that if two cohered discs were placed in the receiver of the air-pump they would spontaneously separate without the air's pressure to keep them together. However, when the receiver was evacuated, they did not separate - a result which Boyle blamed on leakage and the fact that he could not get enough air out of the receiver to reduce the air's pressure to an appropriate level. It should be noted here that Boyle's definitions of "pressure" and "spring" were never clearly defined, which we shall see is one of Hobbes's major complaints.

The air-pump granted access to a whole new branch of "elaborate" experiments. In order to witness the phenomena produced by the pump, one had to have access to a pump - which was vastly expensive and difficult to build. However, the space in which the existing pumps did work was arguably a public space - albeit a restricted one. "The laboratory was, therefore, a disciplined space, where experimental, discursive, and social practices were collectively controlled by competent members". The collective viewing of the air-pump experiments avoided the problem of single eye-witness testimony (which was unreliable), and it offered a space for discourse. This social space for discourse had two important restrictions: "dispute over matters of fact" was not allowed, and "the rules of the game by which maters of fact were experimentally produced" was not to be disputed. "In Boyle's view the capacity of experiments to yield matters of fact depended not only upon their actual performance but essentially upon the assurance of the relevant community that they had been so performed". In order to expand his audience (and credibility) Boyle recommended to the academic community that replication was crucial, though he admitted that others " find it no easy task". As such, the literary technology was used to create "virtual witnessing" - a technique in which description of the experimental scene is written so that the reader can envision the experiment. "Stipulations about how to write proper scientific prose were dispersed throughout experimental reports of the 1660s, but he also composed a special tract on the subject of 'experimental essays.'" Everything about how Boyle instructed other experimentalists to write stressed honesty. He wanted readers to read circumstantial accounts of failed experiments as well as successes, and he asserted that all physical causes should be stated as only "probable."

In sum, Boyle's theory of knowledge production revolves around assent. All three technologies work towards allowing as many people as possible to come to an agreement about a "matter of fact."