Leviathan and The Air-Pump - Chapter IV: The Trouble With Experiment: Hobbes Versus Boyle

Chapter IV: The Trouble With Experiment: Hobbes Versus Boyle

As the chapter title suggests, this chapter focuses on how these two historical figures interacted. It starts with a list of Hobbes' criticisms of Boyle:

- was skeptical about the allegedly public and witnessed character of experimental performances, and, therefore, of the capacity to generate consensus, even within the experimental rules of the game.
- He regarded the experimental programme as otiose. It was pointless to perform a systematic series of experiments, for if one could, in fact, discern causes from natural effects, then a single experiment should suffice.
- He denied the status of "philosophy" to the outcome of the experimental programme. "Philosophy", for Hobbes, was the practice of demonstrating how effects followed from causes, or of inferring causes from effects. The experimental programme failed to satisfy this definition.
- He systematically refused to credit experimentalists' claims that one could establish a procedural boundary between observing the positive regularities produced by experiment (facts) and identifying the physical cause that accounts for them (theories).
- He persistently treated experimentalists' "hypotheses" and "conjectures" as statements about real causes.
- He contended that, whatever hypothetical cause or state of nature Boyle adduced to explain his experimentally produced phenomena, an alternative and superior explanation could be proffered and was, in fact, already available. In particular, Hobbes stipulated that Boyle's explanations invoked vacuism. Hobbes's alternatives proceed from plenism.
- He asserted the inherently defeasible character of experimental systems and therefore the knowledge experimental practices produced.

Hobbes criticized Boyle's experimental space for being private (as it was exclusive to everyone but empiricists) and insisted that the space had a "master" - which undermined Boyle's concept of free discourse and consensus to generate matters of fact. Also he criticized the fact that, since the whole experimental community must come into agreement before a "matter of fact" can be produced, the whole experimental community must view the same demonstration at the same time. This was an obvious impossibility and was problematic for Boyle because "If they were not witnessed simultaneously and together, then in what ways was the evaluation of experimental testimony different from the evaluation of testimony generally?"

Hobbes also criticized the air-pump itself, saying that "the physical integrity of the machine was massively violated." He asserted that "it was impossible to understand the air-pump experiments 'unless the nature of the air is known first.'" This was important for three reasons: (1) because Hobbes said the fluidity of the air ruled out the ability to produce an impermeable seal (2) because describing the air as mixture allowed Hobbes to explain the pumps actions (drawing out the course aspects of the air and leaving behind the more subtle fluid) and (3) because Hobbes said that, since Boyle could not offer a cause for the spring of the air, that made him an inadequate natural philosopher. Indeed, it was Boyle's recommendation to ignore causes that Hobbes found intolerable. It was not an objection to the empirical method. Hobbes only ever doubted the senses as a reliable source of information. He makes an example of the motion of a person's blood, "for no one feels the motion of their blood unless it pours forth," as proof of the unreliability of the senses. Yet he did not object to Harvey's work to prove the motion of the blood - rather he even considered himself a "methodological ally" of Harvey's "both denying the foundational nature and of personal experience."

"Thus for Hobbes, the task of the natural philosopher was to approach as near as he could to the products of the geometer and the civic philosopher" while "Boyle's compulsion was only partial; there was room to differ and tolerance was essential to the maintenance of this partial and liberal compulsion. Managed dissent within the moral community of experimentalists was safe. Uncontrollable divisiveness and civil war followed from any other course."