Epistemology a branch of philosophy that investigates the origin, nature, methods, and limits of human knowledge (Dictionary.com v 1.1). Epistemology attempts to answer the question how do we know what we know? Epistemology Metaphysics Axiology But is it really possible to claim knowledge of anything? In epistemology the greatest challenge is to defend knowledge in the face of skepticism. Philosophical Skepticism: view that knowledge is beyond reasonable proof, highly uncertain or totally impossible. The Ancient Greek Skeptics The Skeptics of ancient Greece rejected the idea that we can have any certain knowledge. All arguments were ultimately based on assumptions that cannot be proven. All beliefs are ultimately arbitrary. Greek Skeptics would often deliver two speeches back to back one that beautifully proved an idea and then a second that would tear it to shreds. WHY BOTHER? By skepticism we arrive first at suspension of judgment, and second at freedom from disturbance --Sextus Empiricus Diogenes: Master Cynic Skepticism prompted some, like the famous Greek cynic Diogenes to drop out of society altogether in search of a simple, raw, honest existence. Because they saw no real distinction between: Distinctions between yours and mine, public and private, native and foreigner were merely man made constructs. Social norms were meaningless. Diogenes deliberately challenged these conventions by shocking and disgusting people by not washing, not dressing, and living in a burial urn. History remembers him as an eccentric thinker and social critic, in his time many viewed him as a freak and social nuisance. Self-Refuting Argument An argument where one or more of the premises contradicts another premise or the conclusion. Some in his day saw something admirable in Diogenes including the richest most powerful man at that time (or any perhaps), Alexander the Great, who in a famous tale, offered to give Diogenes whatever he desired. Diogenes reportedly asked Alexander to move out of the way, so he could continue working on his tan. In the case of the Skeptics Pencil the skeptic affirms the very thing he is trying to deny. He must accept sensory information as being reliable in order to show that it is not. Truly, If I were not Alexander, I would wish to be Diogenes. --Alexander the Great 1
Philosophical Skepticism: view that knowledge is beyond reasonable proof, highly uncertain or totally impossible. Critique: Total (universal) Skepticism about the possibility of knowledge is self-refuting. The skeptic must have some knowledge of the world in order to determine that knowledge is not possible. Is man the measure of all things? Socrates: well then, perhaps we ought to say that your belief is true for you, but fake for all these thousands of people. What do you think? Theodorus: It looks as though the argument leaves us no choice. Socrates: what does all this entail for Protagoras? Isn't it necessarily the case that if he didn t believe in man being the measure, and if the common run of mankind didn't either (as in fact it doesn t), then this book of his, The Truth, would be true for no one? He did believe it, however, But most people don't share this belief. The first notable consequence of this is that the idea is more false than true, in proportion to the extent that the unbelievers outnumber the believers. Is man the measure of all things? Theodorus: That necessarily follows from the premises that its truth and falsity are dependent upon individual impressions. Socrates: And there is a second consequence, which is exquisite. In in saying that everyone believes what is the case, he is conceding the truth of beliefs which oppose his own: In other words, he is conceding the truth of the opinion that he is wrong. Theodorus: Yes. The Recoil Argument The recoil argument is a classic argument against extreme relativism and/or skepticism. It attempts to show that the relativist actually believes in universal truths in this case the universal truth, that there are no universal, only relative truths. But if all truths are relative, so are the truths of the relativist. René Descartes (1596 1650) What if there was an evil demon, determined to deceive you? Everything you experience from the ordinary world is just an elaborate illusion created by the demon. Could you know anything with certainty? 2
Cogito ergo sum I am thinking, therefore I am Descartes Answer: You can know that your self exists. But how do we know the demon didn t trick you into believing you exist? But how do we know the demon didn t trick you into believing you exist? The Demon Cannot make both things simultaneously true: 1. I think that I exist 2. I am wrong in thinking thins Thought Experiment Descartes concludes that we can have certain knowledge of clear and distinct ideas through an intuition of the mind without the aid of sensory experience (a priori) The physical properties of wax can change depending on it s temperature. But we recognize the melted candle has the same wax not by pure sensory experience (according to Descartes) it is my mind alone that perceives it a priori and a posteriori a priori (prior to ) A proposition is knowable a prioriif it can be known without any experience of the natural world. a posteriori (posterior to ) Aproposition is knowable a posteriori if it can only be known through experience of the natural world Examples of a priori knowledge Axioms of Logic Basic principles in mathematics & geometry The concept of infinity The concept of universal Pythagoras Pythagoras (580 500 BCE) was a philosopher and mathematician from the Greek Island of Samos. There he lead a group of devoted followers in a secretive philosophical/religious cult which viewed numbers as divine. 3
Axiom:a self-evident truth that requires no proof. In fact they can t be proven, because they are the very grounds on which any attempt to prove anything must rest. Irrefutable Truth The Commandments of Thought 1. thou shall always obey the Law of Identity a = a (a thing is itself) 2. Thou shall Not violate The Law of Non-Contradiction A not a Rationalism Rationalism: The position that, through reason alone, without the aid of sensory experience, we can arrive at absolute, fixed and certain knowledge. (a thing cannot be itself and not itself at the same time and in the same respect) Features of the Rationalist s Perspective 1. Genuine knowledge should be certain knowledge. 2. Knowledge from experience is often unreliable. 3. Knowledge gained through sense experience can only be fully understood by using concepts/principles not found in experience. Features of the Rationalist s Perspective Q. But how can pure thought, unaided by experience, give rise to knowledge? A. The basic contents of reason (or first principles) are innate. Innate Ideas: Ideas already present within the mind. They are not invented nor discovered through experience. Critiques of Rationalism 1. s derived by pure reason do not usually tell us much by themselves (ex. valid syllogisms only clarify matters, their conclusions do not reveal anything not known from their premises). Most a priori concepts analytic they are true by definition (ex. No bachelors are married men). 2. Philosophers such as Spinoza, Leibnitz, Descartes all constructed elaborate systems of metaphysics supposedly based on pure reason. But these systems all contradicted each other. 3. Philosophical Paradoxes expose flaws in the way we reason about the world Can you make sense of these statements? Paradox: An assertion that is self-contradictory, though based on a valid deduction from acceptable premises. The Liars Paradox: A Cretan sails to Greece and says to some Greek men who are standing upon the shore: "All Cretans are liars." Did he speak the truth, or did he lie? Is the following sentence true or false? This Sentence is False If the sentence is true, then it must be false If the sentence is false, then it must be true Russell s Paradox: In a village, the barber shaves everyone who does not shave himself/herself, but no one else.who shaves the barber? 4
The Blank Slate (no innate ideas) Proposed by John Locke (1632-1704) At birth the human mind is a blank slate on which experience writes. The mind receives and stores information and (over the course of a lifetime) forms complex ideas from the comparison and combination of sensations. Locke s theory of knowledge In Locke s theory several independent elements relate to each other in an entirely mechanistic way to form knowledge of the world 1. The objectof the material world. 2. Sensations(sense data) emitted by objects and transmitted as impulses by our five senses. 3. Ideas the images, impressions produced in the mind from those impulses the immediate object of perception, thought, or understanding 4. The subject a mind which is able to perceive these ideas, reflect on them (combing impressions) to construct knowledge. Empiricism Empiricism: The position that knowledge has its origins in and derives all of its content from sense-experience/observation. Features of Empiricism 1. Ideas resemble or are representative of real things. We form ideas from contact with the real world, and reflecting on experience. Primary Qualities: qualities inherent in an object (i.e. size, shape, weight, etc.) Secondary Qualities: qualities sensation imposes on an object (i.e. color, smell, texture) but nevertheless communicate something true about the object (they are not just illusions). Features of Empiricism 1. Genuine knowledge can be fallible. In fact, we discover the limits of our knowledge if we are to avoid mistakes. 3. All true knowledge should be publicly verifiable not just based on intuition or faith (you should be able to show someone, so that they may see for themselves that your ideas are correct) 4. Assumes that nature behaves in an orderly and predictable ways. Critiques of Empiricism 1. Empirical evidence cannot provide knowledge that is certain. How can we move from a limited set of observations, to a universal truth? 2. Empirical evidence alone cannot establish many common-sense notions that even empiricists accept (ex. Is there a physical world outside our mind? Do objects continue to exist when we are not observing them? Do other minds exist, since we can never directly observe the thoughts of another?) 5