WH 1112 The scientific revolution

The Scientific Revolution

Kepler, Galileo, Descartes, and Newton

• -Individuals, such as Nicholas Copernicus, began to use mathematical calculations to reveal how the world, and other planets ought to move.• Copernicus, paving the way for all future astronomers, argued that his calculations must be physically true.•He offered abstract mathematical arguments to support his claims regarding natural philosophy

Kepler• Johannes Kepler was a German mathematician, astronomer, and astrologer.• - A key figure in the 17th century scientific revolution, he is best known for

his laws of planetary motion, These works also provided one of the foundations for Isaac Newton's theory of universal gravitation.• - As a convinced Copernican, Kepler was able to defend the new system on

different fronts: 1. against the old astronomers who still sustained the system of Ptolemy, 2. against the Aristotelian natural philosophers, 3. against the followers of the new “mixed system” of Tycho Brahe—

whom Kepler succeeded as Imperial Mathematician in Prague—4. and even against the standard Copernican position according to

which the new system was to be considered merely as a computational device and not necessarily a physical reality.

• - Kepler mastered, like the best scientists, the most complicated technical issues, especially in astronomy, but he always emphasized his philosophical, even theological, approach to the questions he dealt with:• - God manifests himself not only in the words of the Scriptures but also in the wonderful arrangement of the universe and in its conformity with the human intellect.• - Thus, astronomy represents for Kepler, if done philosophically, the best path to God.

Scientific Realism•Realism is a constant and integral part of Kepler's thought, and one which appears in sophisticated form from the outset.• The reason for this is that his realism always runs parallel to his defense of the Copernican worldview, which appeared from his first public pronouncements and publications.• Traditionally, realism more generally is associated with any position that endorses belief in the reality of something.

•Scientific Realism is an epistemically positive attitude towards the outputs of scientific investigation, regarding both observable and unobservable aspects of the world.•Scientific realism also means that to accept scientific theory is to think that it is at least approximately true, and that later and more successful theories are closer approximations of truth.

Instrumentalism-Instrumentalism, on the other hand, treats science as an instrument to explain and predict phenomena rather than an approximation of the objective reality.

-Instrumentalism sees the focus of realism as irrelevant and instead suggests that science is an instrument and it should be evaluated based on how good it can produce predictions and usable results.

-Hypotheses and scientific laws are nothing more than “instruments” for describing and predicting phenomena (seldom for explaining them).

Kepler and Realism:• -Building off the writings of Copernicus, Johannes Kepler argues in a similar way for the viability of mathematical descriptions of reality.• - Kepler suggests that the purpose of a hypotheses is to actually describe a physical phenomenon.• Kepler gives a detailed explanation of what constitutes an astronomical hypotheses: “… (the astronomer) promises to demonstrate with syllogistic necessity both those observed positions of the stars…and also, so he hopes, those which are about to appear in the future”

- With this definition Kepler presents a clear distinction between a true astronomical hypothesis and a false one, namely, accurate calculations and the prediction of future phenomena.- This allows Kepler to demarcate between astronomy and non-astronomy, and to claim that any hypothesis that does not meet this definition is clearly false.- A hypothesis must “…be true in every respect” . Hypotheses are not simply devices used to organize data, but rather they tell us something real about the world.

Galileo

-Galileo Galilei 15 February 1564 – 8 January 1642), was an Italian astronomer, physicist, engineer, philosopher, and mathematician who played a major role in the scientific revolution during the Renaissance.

-- His contributions to observational astronomy include the telescopic confirmation of the phases of Venus, the discovery of the four largest satellites of Jupiter (named the Galilean moons in his honour), and the observation and analysis of sunspots.

-- Galileo's championing of heliocentrism and Copernicanism was controversial within his lifetime, when most subscribed to either geocentrism or the Tychonic system.

- Galileo later defended his views in Dialogue Concerning the Two Chief World Systems, which appeared to attack Pope Urban VIII and thus alienated him and the Jesuits, who had both supported Galileo up until this point.

• -The philosophical thread that runs through Galileo's intellectual life is a strong and increasing desire to find a new conception of what constitutes natural philosophy and how natural philosophy ought to be pursued.• What Galileo accomplished by the end of his life in 1642 was a reasonably articulated replacement for the traditional set of analytical concepts connected with the Aristotelian tradition of natural philosophy.• He offered, in place of the Aristotelian categories, a set of mechanical concepts that were accepted by most everyone who afterwards developed the ‘new sciences’, and which, in some form or another, became the hallmark of the new philosophy.

• In the place of Aristotle Galileo left only one element, corporeal matter, and a different way of describing the properties and motions of matter in terms of mathematics. • In doing so Galileo changed the acceptable way of talking about matter and its motion, and so ushered in the mechanical tradition that characterizes so much of modern science, even today.• -. Galileo introduces an approach to the study of nature that is centered on mathematics.

• In his book The Assayer, Galileo states the following:• “Philosophy is written in this grand book, the universe, which stands continually open to our gaze. But the book cannot be understood unless one first learns to comprehend the language and read the letters in which it is composed. It is written in the language of mathematics, and its characteristics are triangles, circles, and other geometric figures without which it is humanly impossible to understand a single word of it; without these, one wanders about in a dark labyrinth.”

• - Rather, true knowledge is gained by reading the book of nature. Nature, according to Galileo, is something which presents itself to us and is something which can be understood through the use of mathematics.• - mathematics is something that is found in nature and is the means by which nature operates.• - The naturalization of mathematics allowed Galileo to legitimate sciences which had previously been considered of secondary importance, most notably Galileo established mechanics as a science.

Galileo and the Church• - In late 1632, after publishing Dialogues on the Two Chief World Systems, Galileo was ordered to go to Rome to be examined by the Holy Office of the Inquisition.• - Finally, in April 1633 Galileo was called before the Holy Office. This was tantamount to a charge of heresy, and he was urged to repent. • -Specifically, he had been charged with teaching and defending the Copernican doctrine that holds that the Sun is at the center of the universe and that the earth moves.• - Galileo was called four times for a hearing; the last was on June 21, 1633. The next day, 22 June, Galileo was taken to the church of Santa Maria sopra Minerva, and ordered to kneel while his sentence was read.

• I have been judged vehemently suspect of heresy, that is, of having held and believed that the sun in the centre of the universe and immoveable, and that the earth is not at the center of same, and that it does move. Wishing however, to remove from the minds of your Eminences and all faithful Christians this vehement suspicion reasonably conceived against me, I abjure with a sincere heart and unfeigned faith, I curse and detest the said errors and heresies, and generally all and every error, heresy, and sect contrary to the Holy Catholic Church. (Quoted in Shea and Artigas 194)

• - Legitimacy of the content, that is, of the condemnation of Copernicus, is much more problematic.• - Galileo had addressed this problem in 1615, when

he wrote his Letter to Castelli (which becomes known as the Letter to the Grand Duchess Christina).• - In this letter he had argued that, of course, the

Bible was an inspired text, yet two truths could not contradict one another.• - So in cases where it was known that science had

achieved a true result, the Bible ought to be interpreted in such a way that makes it compatible with this truth.• - The Bible, he argued, was an historical document

written for common people at an historical time, and it had to be written in language that would make sense to them and lead them towards the true religion.

Rene Descartes• René Descartes was a French philosopher, mathematician, and scientist. • He has been dubbed the father of modern philosophy, and much subsequent Western philosophy is a response to his writings, which are studied closely to this day.• Descartes's influence in mathematics is equally apparent; the Cartesian coordinate system • -Rene Descartes, building off of Galileo, sought to establish what he called the “mathesis universalis,” or the universal mathematics.

• The reason for basing all sciences on mathematics is simple, Descartes states that “Of all the sciences so far discovered, arithmetic and geometry alone are, as we have said above, free from the taint of falsity or uncertainty” .• - Descartes claims that mathematics alone arises from pure and simple “intuition,” that is, mathematical propositions are not derived from sense experience, which is subject to interpretation.• The combining of arithmetic and algebra with geometry, by demonstrating a direct correlation with the numbers used in the former with the figures in the later, resulted in what Descartes called “analytical geometry”.

• - By linking arithmetic and algebra with geometry Descartes was able to formulate a mathematical way of describing space.• - To use the words of E.A. Burtt, “He perceived that the very nature of

space or extension was such that its relations, however complicated, must always be expressible in algebraic formulae…”• - Descartes speculations concerning the nature of matter and extension

lead him to posit his famous vortex theory.• - The implication of Descartes statement is that motion and rest are

inherent qualities of matter itself. An object moves because God has created that object to move. This statement also excludes the existence of a vacuum.• - Space consists of a fine matter that Descartes refers to as “ether”. The

universe is essentially “full” of matter and an object moving through space is communicating this property of motion through the impact of the object against other matter.

Isaac Newton • -Sir Isaac Newton 25 December 1642 – 20 March 1726 was an English physicist and mathematician who is widely recognized as one of the most influential scientists of all time and as a key figure in the scientific revolution.• -His book ("Mathematical Principles of Natural Philosophy"), first published in 1687, laid the foundations for classical mechanics. Newton made seminal contributions to optics, and he shares credit with Gottfried Leibniz for the development of calculus.

• -Newton's Principia formulated the laws of motion and universal gravitation, which dominated scientists' view of the physical universe for the next three centuries.• -By deriving Kepler's laws of planetary

motion from his mathematical description of gravity, and then using the same principles to account for the trajectories of comets, the tides, the precession of the equinoxes, and other phenomena, Newton removed the last doubts about the validity of the heliocentric model of the Solar System.• - This work also demonstrated that the

motion of objects on Earth and of celestial bodies could be described by the same principles.

Principia• -In Book I of Principia, Newton opened with definitions and the three laws of motion now known as Newton's laws.• 1. (Law of inertia): A body at rest remains at rest and a body in motion continues to move at a constant velocity unless acted upon by an external force.• 2. A force F acting on a body gives it an acceleration a which is in the direction of the force and has magnitude inversely proportional to the mass m of the body: .• 3. Whenever a body exerts a force on another body, the latter exerts a force of equal magnitude and opposite direction on the former. This is known as the weak law of action and reaction.

•-Book II presented Newton's new scientific philosophy which came to replace Cartesianism.•-When Newton wrote the Principia between 1684 and 1686, he was not contributing to a preexisting field of study called mathematical physics; he was attempting to show how philosophers could employ various mathematical and experimental methods in order to reach conclusions about nature, especially about the motions of material bodies.

• -These rules were stated in the Principia and proposed that

• (1) we are to admit no more causes of natural things such as are both true and sufficient to explain their appearances,

• (2) the same natural effects must be assigned to the same causes,

• (3) qualities of bodies are to be esteemed as universal,

• and (4) propositions deduced from observation of phenomena should be viewed as accurate until other phenomena contradict them.

• "As in mathematics, so in natural philosophy the investigation of difficult things by the method of analysis ought ever to precede the method of composition. This analysis consists of making experiments and observations, and in drawing general conclusions from them by induction...by this way of analysis we may proceed from compounds to ingredients, and from motions to the forces producing them; and in general from effects to their causes, and from particular causes to more general ones till the argument end in the most general. This is the method of analysis: and the synthesis consists in assuming the causes discovered and established as principles, and by them explaining the phenomena preceding from them, and proving the explanations."