From Socrates To Sartre; #12; How Do You Know?

Do you believe that we are living in a time of progress in scientific knowledge in nuclear physics space exploration communication by satellite electronic technology the discovery of DNA the genetic building blocks of life the control of diseases the improvement of Agriculture. And do you believe that this vast accumulation of knowledge is continually improving in certainty and spinning off more and better technologies for the benefit of human life. If you do you are an eighteenth century mind a mind that believes in the truth and progress of science and its benefits to humanity. And David Hume the philosopher to whom we are about to turn will drop a bomb on your belief in the truth and progress of science in his first philosophic work a treatise of human nature. The time is 1740 almost exactly 100 is since Descartes wrote the meditations and sixteen forty one and the world has profoundly changed during the period of one hundred twenty five years from Descartes Sdeath and 16:50

to the death of Hume and 1776. The philosophic life of Europe was at the highest point of intensity and self-confidence of vitality and optimism. It has ever known this period from 16th 52 1770 is known as the Age of Enlightenment. Our own philosophical President Thomas Jefferson was an Enlightenment philosopher the philosophic outlook and the mood of the Age of Enlightenment swept across Europe and America. This was the source of the greatest surging self-confidence the vitality and optimism the age of enlightenment perceived itself as the age in which the light of human reason. Was replacing the darkness of the Middle Ages replacing scholastic philosophy religious dogmatism and political absolutism. So great and widespread was the optimism of the age of enlightenment that it could only have come from many different sources from the rapid growth of trade and industry. The rise of the upper middle class and especially from the

vitality and progress of the new sciences. The greatest single achievement in the new sciences was that of the British physicist Sir Isaac Newton in his great work called The mathematical principles of natural philosophy written in sixteen eighty seven Newtons principles as this treatise came to be called was without doubt the centerpiece and the most esteemed of all the scientific achievements of the Age of Enlightenment. It was so tremendous a work of synthesizing the scattered fragments of existing scientific knowledge under a few simple principles that it stands forth as one of the greatest scientific achievements of any age. Newton soon became the very symbol of the Enlightenment the very symbol of the power of scientific reason to discover the rational laws which govern the physical universe. The entire physical universe according to Newton is mechanical a world machine. Everything about the machine from the motion of the planets to the falling of an

apple from a tree can be explained by the mechanical laws of motion. The physical universe is thus through and through causal in all its workings. The universe is a system of causes and the necessary effects. Such a system is called deterministic. Everything that happens in it is necessary and the inevitable result of antecedent prior causes. Nothing can be other than what it is. Everything is what it is by causal necessity no material body can be free from this necessary causal determinism. Under the influence of Newton the eighteenth century Enlightenment philosophers asked if this ickle nature is a harmonious order governed by necessary laws of nature which reason can discover. Why is this not also true of human nature as well. Is not the human sphere also part of nature. And is it not also governed by harmonious orderly natural laws. In England the philosopher John Locke

argued in 60 90 that there is indeed a law of human nature governing all human beings and that it is knowable by human reason. The law of nature for human beings. John Locke argues was that all human beings are equal under the law. All are rational all have the same natural rights of life liberty and property and the same obligations not to infringe upon others rights. John Locke's words are memorable he says and reason teaches all mankind who will but consultants that being all equal and independent no one ought to harm another in his life. Hell's liberty or possessions with these words. John Locke justified the English Revolution of 69 88 often called the bloodless revolution which firmly ended the absolutism of the British monarchy and placed power in the people and their representatives in volume and Locke's words affirming a law of nature and natural rights for all human

beings were soon used to justify the American revolution of 1776 and the French Revolution of 1789. And these words entered loud and clear into the Declaration of Independence of the United States of America in the language of our president Thomas Jefferson. We hold these truths to be self-evident that all men are created equal that they are endowed by their Creator with certain unalienable Rights that among these are Life Liberty and the pursuit of happiness. For the Age of Enlightenment human reason was Cain. It had discovered the laws of physical nature and of human nature. But in the face of the Age of Enlightenment which based its optimism on the part was of reason to discover necessary laws of nature and other viewpoint totally different was developing which was destined to undermine and destroy the self confident rationalism of the Age of Enlightenment. This other viewpoint was of course empiricism

which relies on observation by the senses and experimentation as the only reliable source of any knowledge that we can have. And parasitism arose in the early years of the 17th century under the same pressure as rationalism was to try to offer a theory of the method used by the new sciences which were the most important single development of the entire modern world. What kind of method did Newton use in establishing his law of gravity. Both rationalists and empiricists claim Newton for their side. Rationalism as weve already seen is the claim that reason has primacy is the most important source and test of truth. Rationalism agrees with Descartes that in all areas in which knowledge is sought We begin with clear and distinct self evident and true axioms from which we did use of the truth. Constructing a deductive logical system of truths. This is how the

rationalist clane Newton constructed the deductive system of mechanics by reason he did used from basic concepts such as mass energy and from the laws of motion. An explanation of the entire physical universe. But empiricism looks at the work of Newton and points out that Newton's method was by no means like Day cards. Newton's method they say was just the opposite. Newton the empiricist clane began with observation of facts with the data of sensory experience aided by new scientific instruments in order to find regularity lawfulness and order. Only a little Was Newton able to construct a logical system out of the laws he had discovered. Who were the empiricists the great names of empiricism are all British. The high point of the flourishing of empiricism is in England Scotland and Ireland in the 17th and 18th century as philosophical rationalism is linked with

Descartes and with French and continental European culture. So philosophical empiricism is linked with the philosophers and with the culture of Great Britain the classical British empiricists work John Locke who wrote the essay concerning human understanding. George Barclay who wrote a treatise concerning the principles of human knowledge and the great David Hume who in 1738 wrote the treatise of human nature with Francis Bacon as a forerunner the development of the logic of British empiricism was the work of these three philosophers. Locke Barclay and HUME The fundamental principle of empiricism is that sense perception is the only reliable source for gaining knowledge and for testing any claims to knowledge that are made. Sense perception includes direct observation of other senses. The use of instrumentation such as the telescope and the microscope and the use of

experimentation. From the very early days of empiricism in the work of John Locke empiricism shows itself to be a deliberate and defiant rejection of philosophical rationalism and especially all of Descartes. All the empiricists rejected what they came to call Cartesianism the rationalistic building of a great big duct of systems of philosophy pointing to have grasped by the powers of reason alone. The nature of total reality of man nature and God and claiming to have achieved also complete mathematical certainty in this knowledge by the use of a logical deduction from self evident axioms in shock this negation and rejection of this all of the empiricists are suspicious of metaphysical systems constructed by reason empiricism constructs no great metaphysical systems of philosophy.

It offers no speculations. It offers no worldviews for humans to live by. It remains only a theory of knowledge and at his stem ology which is a word derived from the Greek meaning simply theory of knowledge. It is a theory of what we can know empiricists clain that we can know reliably only what comes to us by sensory experience by observation and experiments. Thus empiricism claims that the only adequate basis for knowledge is that sensory experience the flux of the sensible world which the two great rationalists Plato when Descartes rejected as an inferior way of knowing. And from this basis in sensory experience as the source and test of knowledge empiricism as a theory of knowledge becomes a powerful engine of destruction.

A wrecking ball which is soon swung against all the structures built by reason in philosophy and theology. And do you ma lushes them as no knowledge at all. How was this done. Beginning with a lock empiricism as a theory of knowledge raises two questions about our knowledge. First for any statement in any field whatsoever that purports to tell us anything about the world the empiricist raise the seemingly simple seemingly harmless little question how do we know to this little question. There is only one kind of Monsour that an empiricist will accept. And the answer that says I know by pointing to these sensory observations that are the source of my knowledge to the empiricists If you cannot answer the question how do you

know by showing that your knowledge rests upon sensory experience upon observation of data or upon experimentation with data. You are bankrupt. You have no knowledge. Your claims to knowledge are worthless. But Candy carts metaphysical dualism of mind and matter meet the question how do you know. By showing that this dualism is based upon sensory observation. Obviously not. It is based not on sensory observation but upon reason. Can Plato's theory of the forms can Plato's divided line of knowledge pass the empiricist test question. How do you know. By pointing to empirical observations. Obviously not. It was based upon rational reflection upon reason. Do you hold to any philosophic beliefs about the world. Or do you have any religious beliefs about a divine being or any political philosophy about how society ought to be governed.

If so is there any way in which you can successfully answer the empiricism question. How do you know what observations of data. What sense perceptions. What scientific experiments can you point to as the sole source of your philosophic worldview. Your conception of a divine being or your political philosophy. Obviously there are none. And so your claims are ready for demolition by the empiricism wrecking ball. The second question which the empiricists raise is a more fundamental one. This second question which the empiricists raise is this. What kind of instrument is the human mind and what are its limits. What is the human mind quipped to know. This second question is also intended to devastate reject rebuke and demolish Descartes and all builders of rational theoretical structures of philosophy.

Attacking Descartes and all such metaphysical builders the empiricist say before you undertake to construct a great philosophic system. Why don't you wash the basic question is the mind equipped for such metaphysical excursions into the heart of reality. Are there perhaps limits as to what the mind can no limits as to the origins of its ideas. Limits us to the certainty it can achieve. These two questions How do you know. And what are the limits of knowledge dominate the powerful development of British empiricism from Locke to Barclay to human this development gathered momentum as the devastating relentless questions become more sharply understood by the empiricist themselves. John Locke as the earliest in the line of British imperialism is as may be expected the most conservative and the least

destructive in pursuing the hard questions of the empiricist programme. Yet he states clearly and profet equally the role which empiricism will have in the subsequent development of philosophy. There are says Lock Master Builders whose mighty designs in advancing the sciences will leave lasting monuments to the admiration of posterity. But Locke adds It is ambition enough to be employed as an under Labor in clearing the ground a little and removing some of the rubbish that lies in the way of knowledge. Locked in these prophetic words is looking into the future a horizon of philosophy. It will indeed be the case that empiricism by the two questions How do you know and what are the limits of knowledge. Will cost so much adult upon the construction the building of great systems of

philosophy that there will come a time when there will be no more master builders in philosophy. And there are no master builders in philosophy today. The role of philosopher is also as John Locke prophesied to be and under a labor of clearing the ground a little removing rubbish. What is the rubbish. The philosopher removes. Why rationalistic rubbish of course such rubbish as Plato and Saint Thomas Aquinas and I call it rose. But what is the under labor of clearing the ground for. Since nothing is to be built and there are no master builders the empiricist has no answer to this question except that it is desirable to recognize rubbish and to clear it out. The first rubbish which John Locke decided to clear away was as you would expect a piece of rubbish created by Descartes himself. It was Descartes theory of innate ideas. The theory of innate

ideas is the theory that some ideas are innate in the sense that as Descartes said they are born with us. They are imprinted upon the soul. Examples of innate ideas as you remember are the idea of substance. Cause God and the rational principles of logic. Locke's line of attack against Descartes theory of innate ideas is clear. It is by way of the question how do you know that these ideas are innate in all human beings. What data of experience what sensory observations. What empirical evidence can you offer in support of this theory. Can you show by pointing to the data that all humans from infancy on possess these ideas. But surely on the basis of empirical evidence there are many who do not possess the ideas of God or of logic as infants or ever. Therefore said Locke. The theory of innate ideas is worthless rubbish. The

mind he says is not a closet filled up at birth with such innate ideas the mind he says is an empty closet. Changing the metaphor he argues that the mind is a blank tablet blank white paper on which experience writes and this writing by experience is all the mind can know. A Lock says also that all our ideas have only one source and that is experience. What then is the lock's theory of knowledge. His aim is to show that the origin of our knowledge is in sensory experience in sensation through the mind's receiving impressions made on it by external objects. The only other source of knowledge is our reflecting about our sensory experience. As in reasoning about it. Delving it or believing it along who thinks he is independent of all previous philosophers. Nevertheless takes over from Descartes Descartes view of an

idea as meaning anything the mind thinks about any objects of the mind. Locke also takes over from Descartes the subjectivism of Descartes Descartes view that what I know best is my own mind and its ideas. And last there enters into empiricism the problem inherent in subjectivism which we already found in Descartes that there is a chasm or gap between my own mind with its ideas and the physical objects and human beings which are xtal to me in the physical and social world. How can I get to know them. Since I am confined to knowing my own ideas how can I have a true knowledge of objects as they are independent of my mind in the world. Poor a lock. Who also takes over from Descartes. They karts idea of the physical substances and their qualities exist. Poor law runs into

excruciating really painful problems. As an empiricist Locke can only know what originates in sense perception. He cannot claim to know anything by clear and distinct rational ideas. He cannot claim to know by the help of God. How does he know that physical substances exist. Has he ever had experience of a physical substance. How does he know that our ideas of primary qualities belong to physical objects. And so the wrecking ball of empiricism takes aim at John Locke himself and his theory that physical substances exist and have primary qualities which produce secondary qualities in us. It is George Barclay the Anglican Bishop of Cloyne in Ireland the second in line of the great British empiricists who conducts the attack upon Locke. How could an empiricist indulge in the now outmoded concept that physical substances

exist. Locke had failed to follow through on the basic empiricist principle which is that we can know only what comes to us in sensory experience and so Barkley pushes ahead with the argument of empiricism and demolishes Lawks acceptance of the belief which Descartes and Newton had held that physical substances exist. We can never have sensory experiences of physical material substances as Barkley. We can experience only sensory qualities. What is my actual experience of substance. It is only the experience of qualities. I perceive a tree as of a certain song and shape. I perceive the diameter of its trunk the length of its branches the brown color of its trunk and branches and the green color of its leaves. I touch its rough textures and I smell its Woody aroma. But I can never perceive its substance. All that

I have perceive of the tree are its qualities. I have no perception of a substance the existence of physical substances Buckley goes on to argue is thus only in their being perceived. Physical substances cannot be known to have any other existence than in the qualities we perceive those of Barkley's empiricism is more radical than locks in that Barclay destroys the belief in physical substance which Locke was still clinging to. What follows from Barclay's argument is that the material world exists only in being perceived as qualities thus matter physical substance the physical universe. These do not exist. Bishop Barclay left intact however two major structures of thought he did believe that mental substances exist in the form of finite minds and also in the form of the existence of God

as Infinite Mind. Barkley also believes that the laws of nature which the new sciences had discovered were reliable in their orderliness and regularity. Barclay could not of course say that the laws of nature were laws of physical Bob ject since physical objects for him do not exist. The laws of nature for Bach Lee are only the laws of our own perceptions or ideas. But like Descartes Barkeley called upon God to solve problems in his philosophy. Barclay assured us that with the help of God our perceptions are reliable and orderly and that we can trust in the uniformity of experience and in the dependability of scientific laws. Enter the Scotsman David Hume. The last and most rigorously persistent and destructive of the British empiricists we have seen that Barclay as a bishop of the Church of England had spared from the

wrecking ball of empiricism mental substances in the form of God's mind and human minds. Barclay as a bishop had to spare God's mind and human minds. But Hume googly fully asks the empiricists little question how do you know that mental substances exist. We will see. The idea that there are mental substances God's or man's mind collapses under Hume's attack. But there was a second structure which Barclay left standing and that is the solid reliability and uniformity of scientific laws of nature. Will human let of this last structure stand. The Age of Enlightenment the age of reason of optimism springs from the passionate conviction that human reason had at last discovered many of the true laws of nature and that these laws of nature were absolute and necessarily causal laws

such as the laws of astronomy or the laws of physics the laws of chemistry the laws of physiology and we have seen that the great burst of optimism of the Age of Enlightenment was based upon the belief that the future would see the continued discovery of new scientific laws with which would turn into more and more benefits for the life of humanity. Is not this belief in what the future of science technology and democracy have in store for us. Is not this what you believe in your better your happier your more optimistic moments. It is what the age of enlightenment was passionately committed to and nowhere more than in the hearts of the founding fathers of the United States of America. But Hugh Dean mahl asst. The very foundation of this entire view of progress of the Age of Enlightenment. He shattered the pride of the age of enlightenment

in the necessary causal laws of Newtonian mechanics of physics and astronomy chemistry and physiology. By denying that there are any necessary causal laws at all. How he'll manage to swing the record in all the empiricism. At this rate structure of science we will now proceed to see. There will be more public broadcasting.