As the integrity of the experimental apparatus depended not so much on logos (the primary instrument of the philosopher), but rather on handiness and the right materials (a task often handed over to craftsmen), the role of the experimental philosopher was first and foremost that of the witness of the experimentally produced phenomena. And, just like in the courtroom, the question of the legitimacy of a testimony is always at stake. So, not only the integrity of the experimental apparatus, but also that of its witnesses, was an important condition in order for the observed phenomenon to become a ‘matter of fact’.
To ensure this, the 17th century saw the rise of the first scientific communities, such as the Royal Society of London, of which Robert Boyle was a prominent member. The role of such societies was to guarantee that as many philosophers as possible were the witness of an experiment. Those witnesses were free to judge for themselves what to believe, and a matter of fact was constituted when all believed alike. The goal of the experimental community was to attain universal assent, a goal to which matters of fact would lead the way. “It is not I who says this; it is all of us,” said Thomas Sprat as propagandist for the Royal Society. The production of a fact could never be a private enterprise.
In this way, knowledge became a theatrical and spectacular undertaking. The new philosophers gathered together in laboratories, watching strange machines being operated, producing unseen phenomena. The experimental theatre became a place of popular entertainment. In a letter to his brother, Huygens wrote how he often pretended that his machine was not working, because otherwise he would have to entertain spectators everyday.
To maximize the number of witnesses of an experiment, it was important that the experiment could be spread beyond the laboratorium in which it was performed. In order to ensure this, a detailed report of it had to be provided, such as: “The Pump after this being imploy'd, it seem'd that from time to time the sound grew fainter and fainter; so that when the Receiver was empty'd as much as it us'd to be for the foregoing Experiments, neither we, nor some Strangers that chanc'd to be then in the Room, could, by applying our Ears to the very sides, hear any noise from within; though we could easily perceive that by the moving of the hand which mark'd the second minutes, and by that of the ballance, that the Watch neither stood still, nor remarkably varied from its wonted motion.” Or, in the words of Huygens: “Een slaende horologe daer in geleght, boven op wat werck. Men hoorde de klock vrij flaeuwer dan als de fles vol lucht was. [Put a ticking watch in the receiver, on some fabric. The sound of the watch was quite fainter than when the bell was filled with air.]”
Reports like these not only made it possible to replicate an experiment, but also enabled readers to witness it virtually. Prolixity, naturalism and plainness were the literary virtues advocated by the Royal Society, and a certain style of pictorial representations was encouraged. The ideal report would represent the experiment exactly as it was. Faithfulness to reality was the ultimate value. The philosopher should let the facts speak for themselves, and be nothing more than their witness. In the laboratory, the truth would be up for grabs.