http://m.youtube.com/watch?v=i5TFXyI4UMMI am grateful for this video, which is why I posted the previous post. Newton never created a flawed system or method, he just lived in a time when others would steal or corrupt another's ideas fir financial or social or political gain. His academic papers written in Latin were sometimes written in code for that reason .
Here we see how the fulmination of Betkely to this day clouds the apprehension of Newtons method!
Suffice to say Berkely was well refuted by Cotes aad others at the time,mbut in a time of clerics, clerics rule! And Berkleys ferment had his intended effect regardless of its effect on Newtons reputation: religious philosophers came to heel while those who were atheistic we're forced into a semantic cubbyhole from which they to this day have not emerged!
The ideas of infinite / endless is well defined in philosophy, but in religion it is by design mysterious! Thus to some clerics it is blasphemous to even talk about infinity without acknowledging God or Jesus! But the Greeks did just that , because it is a semantic label for a human experience not a divine one! To any clear thinking Astrologer just as we can count without end, so we can factor without end. But Lucretius and Democritus insisted that there Must be an end to cutting a material object , even if we can continue to break it into parts in our minds! Thus the word atom was given its material significance as the material that can not be divided further!
To accept this stance is to immediately distinguish between matter and spirit. This basic asserted dichotomy underpins the argument between materialists and those who accept an immaterial reality. Clerics of course favoured the latter, but as Berkeley observed many philosophers were abandoning the tenets of the church for a materialist point of view.
Logically there is no irrefutability or either position, and this is what Berkeley was driving home. No one cn deny the other by the tenets of the dichotomous stances, both demand an equal faith response!
However, as logic was intended when designed by the greek schools of Rhetoric, one may present an argument to persuade by fair means or foul, and ridicule, ad Hominem, and many other logical devices were outlined and taught in the schools of rhetorical logic.
Berkeley picked on Newtons infinitesimal notion because he knew his audience did not understand it! He was careful not to claim Newton said, for libel was a serious issue in his day, but cleverly he points out that an apparent contradiction lies at the heart of Newtons method.
Then he asks in an attempt to ridicule : what are fluents,Fluxions and these vanishing quantities?
Now in Europe infinitesimals were considered as a joke ! But this again wasvduevo trying o call them numbers!
Everyone thinks they know what a number is!! Clerics were of the opinion they were ( whatever they are) divinely revealed by God and set out sensibly in the bible and in Nature. Thus infinitesimals were undoubtedly the work of Error or at worst of the devil.
I can not emphasise just how tiring this kind of thinking is! For a classicist to read the Ancient Greek clear exposition of arithmos and how to philosophise quantity with them must have been a huge relief.
So infinitesimals for Newton, like infinity were semantic word labels for endless processes! Once you stop such a process it is by force no longer infinite!!! Thus to use a symbol is not to make it an Arithmos!
2 other things highlight Newtons explanations . Fluents or fluids were time dependent, and his symbol is gor a small moment in time. While an extensive unity may be objectified, time is n intuitive srns that I highly subjective. The sense of duration requires such LanguGe as nascent, evanescent, vanishing etc. a clock, or pendulum do not replace our time sense, they merely provide a scaffolding in which to erect a onsidtent and conventional measure.
The second was a concept of dynamic variation. Even classical philosophers considered forms in static poses or stages of pause. Zeno sets aside time intervals in his famous argument to focus on the clear stages for comparison , thus fluidity is not incorporated in classical Mechanics.
It is still difficult to get this idea across even today! Fortunately we cn use the high speed camera metaphor to capture Newtons vision of fluents and fluxions. We can now visually track a fluid action and see the intensity of a Fluxions by comparing 2 sequential frames in such a movie.
Newton did not divide either. He factored. When you factor you do not Divide you look for the factor that gives a certain quantity, that is you look orthe Quotient!.
Often the concept of multiplication is used to explain quotients, but it is in fact the concept of counting factors of a given form that we need to inculcate. Our understanding of factors is codified in the binomial theorem but essentially the mosaics of old or a pile of bricks demonstrates factors and their equivalent topologies.
The rule not to divide by nothing is therefore patently nonsensical, but when you set up such algorithmic presentations of the factoring process and systematic synthesis or Combinatorial schemes these rules of thumb often pop up.
.let us now consider newtons fancy: suppose we have an infinitesimal moment in a fluid situation. This is like taking a snapshot at a trillion frames a second . The infinitesimal momnt is between frame 1 and 2 ! But that is at a trillion frames a second. What if we increase the frame rate to 10 trillion ? Then frames 1 and 2 now show a different relationship. If the quantities were not fluent there would be no change.
The symbol for this time step can not be fixed and it can not be evaluated because once you do you are no longer fluid! We know how high spped cameras Freeze fluid motion. The concept of freezing fluid motion is entirely novel to Newton. Leibniz still clung to the notion of a differential and that in an extension. Newton realised a differential in time might freeze a fluent and reveal its Fluxions or freeze frame changes.
So what about a term which contains an infinitesimal as a factor? In this case Newton new they were pragmatically useless. They can not be measured but if they could they would make the product so small as to be vanishingly small! Newton does not drop them, he just works with approximations from that point on
There is no need to go to a limit because a fluent is dynamic, continuous and clearly flows before nd after any chosen time frame. The Fluxion for a constant flow should be the same no matter when measured . The tiny piece he ignored in approximating is vanishingly small and not measurable in practice, especially if working at the limit of ones ability to measure.
The approximations of Newtons methods have served a pragmatic technology well.