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Page history last edited by Marek 15 years, 4 months ago

Consider several of the experiments we have examined in this course, among them: Galileo’s inclined plane experiments, the experiments with the barometer and the air pump, Harvey’s experiments to show the circulation of the blood, and Newton’s experimentum crucis. Show how these experiments collectively differ from the Aristotelian conception of empiricism, and how individually these experiments served as influential models for how “modern” science should be done.



The foundation of natural philosophy on Aristotelian empiricism determined its involvement with describing the essential properties of objects they encountered. Since quantitative descriptions were not to speak about the essence of things, the various mathematical studies of nature were considered peripheral. What was left for the natural philosophers was a qualitative description of nature in its proper state. The Scientific Revolution that occurred in the 17th century brought the mathematical sciences into the domain of natural philosophy. The concerns of the natural philosopher expanded to include descriptions of processes, operations and their outcomes. Nature was not only to be observed in its uninterupted state. Artificially produced experiences were also to become part of the knowledge base from which conclusions could be drawn. Galileo's inclined plane experiments, Pascal's experiments with the barometer, Boyle's experiments with the air pump, Harvey's experiments to show the circulation of blood, and Newton's experimentum crucis collectively differ from the Aristotelian conception of empiricism, and individually contributed toward a more modern science.


The goal of philosophy, including natural philosophy, was obtaining truth. The steps form experience toward understanding and truth were very well defined in Aristotle's works on logic, especially his Metaphysics and Posterior Analytics. Experience, for Aristotle, constituted what we would call "common sense" today. "Memories that are many in number form a single experience" Aristotle wrote in his Posterior Analytics (Dear, p. 5). Hence, experiential knowledge was equivalent to familiarity. From these experiences could be established universal claims that were accepted as certain. Certainty was important, because otherwise any demonstrated conclusions could not portend to the status of absolute truth.


Understanding was also well defined. Something was considered understood when it could be explained, and explanation demanded a specification of causes. If a scholar was not speaking of causes, then he was not working towards a development of understanding. From this emerged the object of natural philosophy - to explain phenomena that were already observed.


Thus there was little emphasis on active discovery. Nature, as it existed, unvexed, and unpertubed, had been observed for centuries. Its operations were familiar and only in explanation. This entrenched worldview posed a significant hurdle to experimentation in general and especially quantitative experimentation. Experiments involved artificially generated experiences using specially constructed equipment; carrying them out involved defining quantities and standards of measurement. Thus, experiments could not be called familiar or obvious, and as such did not produce certain claims that could be reasoned from to expand understanding. Since experiments almost by definition could not lead to understanding, they had no purpose in an Aristotelian framework.


The goal again was to arrive at truth. Not any truth about the physical world was considered an advancement of knowledge, however. The key criterion was whether a particular claim spoke of the essence of an object. Aristotle's works determined a classification system for the physical world. The world could be claimed to be understood when a place for each object could be specified. The focus was on the nature of objects themselves, and the processes in which they were involved were only considered when they reflected upon this nature. Although it was possible to say many things about nature and its processes, many of those things were not worth saying.


Francis Bacon wrote about the famous "twisting the lions tail" example. He said that the Aristotelian method simply allows for the observation of the lions in order to understand what they are like. However, Bacon argued that to actually know what they are like one would need to go up and not passively observe the lions, but "twist the lions tail." Thus, Bacon advocated deliberate manipulation by actively producing conditions.


Interested in the cause of falling bodies, Galileo Galilei proposed that falling bodies would descend with an acceleration uniform in time, discounting friction. Galileo conducted mathematical quantitative experiments by rolling balls down an inclined plane, thus constructing a form of falling that is slow enough to be measured, deriving that the distance travelled during uniform acceleration starting from rest is proportional to the square of the elapsed time (d t 2).  According to Aristotle, the heavier body would fall faster than a lighter one of the same shape. However, Galileo concluded from his inclined plane experiments that all bodies fall at the same rate. He also developed a theoretical argument in the Dialogue Concerning the Two Chief World Systems for this conclusion by showing that when two bodies of different masses and different rates of falling are tied by a string, the combination of the two does not fall faster because it has more mass and the lighter body does not keep back the heavier body in its slower descent. Using the hypothetico-deductive method, Galileo made predictions using quantitative mathematics and then tested them in the real world by means of experimentation, though Aristotle would argue that such an experiment alters the actual event in nature and, therefore, one cannot make an accurate conclusion about that event in nature from simulated conditions. Aristotle's philosophy centered about understanding (the why) rather than active discovery (the how) like Galileo, whereas mechanical philosophers followed in a similar pursuit as Galileo, and others, to come up with intelligible causes, and specifically provided a vehicle to quantitatively measure the distance of falling bodies. This quantitative mathematical scientific method was later utilized by Sir Isaac Newton.  


 Pascal, more known for his triangles, enlisted the help of his brother-in-law to contrive an experiment that would help to test the effect of air pressure on a barometer. The details of this experiment, taking the barometer up a mountain and checking the level of mercury at different altitudes, differ very greatly from the Aristotelian idea of studying nature, as it exists. Aristotle would argue that this experiment could not find truth because the barometer did not naturally go up a mountain on its own, not to mention the barometer itself would also not be able to attain truth. Pascal, however, believed, like many mechanical philosophers, that the experiment could lead to truth. Pascal hypothesized that the level of mercury would change as one went up the mountain due to less air pressure.  The experiment then proved his hypothesis. Pascal created a hypothesis, tested it, and then drew conclusions.  The technique that Pascal followed is used very much in modern science.  Today, this procedure today is better known as the scientific method, which was a process that Pascal’s experiment helped, along with the others, to create.


A well-known scientist against Aristotelian thought, Robert Boyle, modified the air pump to do experiments explaining the pressure of air.  He did not believe the theory of a funiculus to hold the mercury in place in a tube.  Through many experiments with the air pump, Boyle was able to conclude that no funiculus existed to hold up the mercury but rather that the air had a natural “spring.”  Boyle’s experiments went against the Aristotelian grain because he drew theories and generalized conclusions from his experiments with the air pump.  Where Aristotelian thought would have said these experiments could not explain truth because they were artificially created, Boyle would argue that because the experiments all worked out very similarly in a quantitative manner that the experiments led to truth. These experiments led to truth contained in a law Boyle created about the quantitative relation of air pressure. Boyle approached a problem, such as the air pump example, and sought to solve the problem with a pre-conceived hypothesis. In this case, the experiments proved his hypothesis correct about a funiculus not existing, and helped to create the law known as Boyle’s Law. Other than using the scientific method, Boyle also contributed to modern science with his addition of his law, which created a way in which to quantitatively relate pressures.


     William Harvey offered three experimental arguments for the circulation of the blood. In one, by cutting up a live snake and experimenting with pinching the vena cava closed and later releasing it again, then performing the same experiment on an artery, he demonstrated on a practical level the relationship between arteries and veins. In another, he tied a ligature around a man's arm and observed what happened above and below the ligature.

    Not just observing nature, Harvey actively interfered with it through his experiments, a method hardly qualified as Aristotelian.  Moreover, he accepted quantitative demonstration as a valid basis for understanding. For example, his quantitative argument claimed that the amount of blood passing through the heart was too great to be supplied by food consumption and used the dissection of sheep and humans as evidence. He assumed that measuring the amount of blood drained from a dead sheep is evidence for what quantities are contained by living ones. 

     Harvey began with establishing observational inconsistencies in former theories of movement of the blood, then proceeded to make his own conjectures and test them experimentally. While he was seeking various causes (as for direction and flow of blood in arteries and veins respectively), the causes he pursued were efficient, and he used experimental evidence to derive them. He performed countless dissections on animals of all kinds as well as humans, a process which perhaps contributed to the staying power of Vesalius' newly established fusion of the roles of doctor and barber which is still retained today. 


Newton's experimentum crucis involved the use of light, prisms and convex lenses in order to observe the mechanics of light. Originally, he believed that light was a homogenous mixture of rays, following the thought of Descartes. He hypothesized that a beam of light shown through a prism would have a circular pattern on a white screen due to the laws of refraction posed by previous philosophers. However, upon investigation Newton discovered that light was in fact composed of a heterogenous mixture of rays. In his experiement, Newton allowed a small sliver of light to shine through a prism. The light beam was then cast through a second prism, a convex lense, and finally onto a white screen. He discovered the light pattern on the white screen to be oblong in shape, rather than circular. 


Newton attributed this finding to the varying degrees of refrangibility of light. In order to confirm this, he devised the experimentum crusis. By refracting light twice he showed that the degrees of refraction for the different colors were different. There was no other possibility. Newton in effect did not use arguments to support his conclusion - performing the experiment was the best way to settle the matter. The outcome also made it possible to quantify color. Newton showed how experimental philosophy is the proper source of knowledge for discovering the nature of science.


The experiment Newton contrived differed greatly from the true study of nature Aristotle practiced. The Aristotelian argument against Newton’s experiment would have stated the setup of the experiment with the light, prisms, and convex lenses was in no way a true study of nature. The setup itself altered nature and this is why an Aristotelian would have argued against the truth obtained by the experiment. Newton, however, like the mechanical philosophers, believed his experiment to show a specific truth. This experiment specifically may have been the only reason for a new theory of light.


Using quantitative science and his experimentum crucis, Newton was able to describe the problems of refrangibility of light in creating and designing telescopes. The presentation of his "New Theory of Light and Colors" was even presented as an explanation of how the idea behind the reflecting telescope formed and why refracting telescopes necessarily distorted an image.  Newton and his followers in science demonstrated a new way of approaching science which involved experimentation and operational knowledge.     


Perhaps the defining characteristic of the Scientific Revolution was the shift from a natural philosophy dedicated to resoning from universal claims to a concept of science emphasizing the processes of experimentation and active discovery. This change, headed by a few elite minds and scholars, established new methods of acquiring true knowledge and changed the focus of knowledge from describing causes to explaining operations. Recourse to experiment became a legitimate argument for establishing claims in natural philosophy. Slowly the view of knowledge gained from experiments shifted from particular to universal. Instead of relying on reasoning and explanation based on what was already known through “common sense” experience, these innovators sought truth through more deliberate means, including, significantly, an increased emphasis on quantitative methods. The previously described experiments reflect a break from the Aristotelian conception of empiricism, and each individually served not only as influential models for how "modern" science should be done, but as promulgators of the concept of science as something to be done.


Comments (16)

Keriann Collins said

at 5:50 pm on Dec 6, 2008

All essay 2 writers who are interested: come meet in the llibrary bubble Sunday night 8 pm to discuss a thesis/direction and perhaps get an outline going. If you can't make it at that time, but might join us later, come up to the computer lab and check the study rooms there.

Garry Polley said

at 9:50 pm on Dec 7, 2008

We have made the outline for the paper. those in attendance were Keri, Allison, Landsey, (leave one off), and Garry.

Garry Polley said

at 10:14 pm on Dec 7, 2008

I've added a rough draft of the paragraph on Pascal's experiment with the barometer.

Garry Polley said

at 10:29 pm on Dec 7, 2008

I've added a rough draft of a paragraph on boyle's experiments with the air pump.

Garry Polley said

at 1:06 pm on Dec 8, 2008

In the paragraph about aristotle I do not think we should write, "There was thus no logical possibility of making discoveries." This is a very strong and I think false statement. Aristotle wrote a books about how to argue with logic and prove things correct with logic... so I don't see how the sentence is correct. I think we could reword it but using the word logic seems false to me. Just let me know what you all think.

Jessica Germer said

at 1:45 pm on Dec 8, 2008

i just added some stuff on harvey and then also in the paragraph about how it compares to modern science. sorry i didn't come to the meeting, my computer was broke this weekend and i could not get on the page. i don't really know what directions that you guys wanted to take this, so let me know if i'm way off base

Garry Polley said

at 2:25 pm on Dec 8, 2008

We are meeting tonight at 6 in the library upstairs near the group study rooms. We have a room reserved so come when you can.

Alyson Collins said

at 4:59 pm on Dec 8, 2008

revamped my part on galileo, still not smooth , but I think its more correct and relevant

Nathan Keller said

at 6:10 pm on Dec 8, 2008

Garry, I agree. I took a shot at it; the sentence in question eventually became "There was thus no major impetus toward active pursuit of fresh discoveries." I made a few more tweaks in the middle part of that section; I see some stuff at the beginning and end I could go after too.

Peter Ramberg said

at 9:48 pm on Dec 8, 2008

A few comments: 1) I'm not sure what you mean by the last part of your highlighted thesis. Your thesis might even be better stated in the last paragraph of part II. 2) Boyle was arguing against the the theory of the "funiculus," not the "finiculus." 3) Try not to get bogged down in recounting all the details of the experiment--you need to illustrate more specifically how these experiments exemplify what you outline in Part II, and importantly, how each illustrates a different method towards experiment. In each case, which comes first, experiment or theory?

Keriann Collins said

at 10:19 pm on Dec 8, 2008

The last edit in the introduction to part two - last paragraph before Galileo, was actually made by Marek.

Garry Polley said

at 9:56 am on Dec 9, 2008

I've edited out completely a paragraph I felt not necessary at all because Boyle was already spoken of and the new paragraph only added an experiment that further explained the existing one, which Dr. Ramberg stated that we were already focusing too much on the experiments as it was. I also tried to compare Newton more to the Aristotelian ideas. I also edited the conclusion a bit.

Alyson Collins said

at 10:51 am on Dec 9, 2008

I got rid of what was previously part three, it seemed just to repeat part IV but in a more illogical way. If think I was wrong can add it back, but they seem pretty much the same.

lindsey said

at 11:00 am on Dec 9, 2008

agree, it was an awkward paragraph.

Jessica Germer said

at 11:54 am on Dec 9, 2008

we really need to take out the outline portion of the essay, it looks messy, but people have been working on it for awhile now and i don't want to steal the lock and make them lose their work. If anyone sees this before class please change it. Thanks

Marek said

at 11:56 am on Dec 9, 2008

I guess you can ahead now. I felt the discussion of Newton distorted what the experimentum crusis was and the last paragraph ended in half the sentence so I attempted a fix.

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