The Practical Side of Philosophy

All this may lead to the conclusion that, unlike science, philosophy is devoted to discussions of questions that have no practical signifi­cance, discussions that bear no useful fruit.

We find nothing dishonorable in discussions that have no prac­tical value, especially when they are interesting and more so when they challenge our prejudices. Moreover, even if one does not value impractical questions, one has to admit that some of the most imprac­tical discussions turned out in time to be of great practical value, so that even the preference for the practical has to make room for the impractical. (“What is the use of a child?” Benjamin Franklin asked rhetorically in this context.) Moreover, we do not quite know what we consider practical; this depends on our values, and the discussion of values traditionally lies at the very heart of philosophy.

For example, the Copernican Revolution was of great practical value because it improved astronomical predictions, which determine future calendars; as long as most people are religious, the calendar is of tremendous practical importance. Indeed, although the Church of Rome officially questioned the theoretical status of Copernicus’ theory, it admitted its practical value and even had missionaries teach Chinese astronomers how to use it. The distinction between use and assent was so tremendous that the terminology of the Catholic Church at the time distinguished clearly between practical and philosophical valuation, where the philosophical assent to a theory was the assertion that it is true.

The great philosophical question of the time was: Is it better to follow tradition or to trust one’s own judgment? This question is not as easy as it sounds because we know that individual funds of knowledge are much poorer than the traditional knowledge - the latter is the product of efforts made over generations in the society in which the individual lives. No single individual possesses so much knowledge, and even combining all the knowledge of any group of friends or colleagues is no substitute for traditional knowledge. To avail oneself of a significant portion of public knowledge, one has to integrate into society and abide by its rules. We do not know what this amounts to, but clearly it is significant.

Many conservative thinkers find themselves, against their will, lead­ing revolutions of all sorts: intellectual, scientific, moral, and even political. Copernicus and Galileo are examples as are the many peo­ple who followed them and agreed that tradition is no substitute for individual freedom of thought, that it is impossible to demand people to follow tradition when they see its defects no matter how valuable it may be. This attitude about tradition, the moderate skepticism about it, is one that is very common in the West, but it received articulation only after World War II. This very articulation is the achievement of recent philosophy - of Karl Popper, to be precise. It is the outcome of a most abstract research project and is of great practical value as individual freedom.

So much for the praise of impractical thinking. Again, we deem impractical thinking essential for cultural existence and, therefore, of the highest practical value for the extra worth that culture brings to our lives.

Some of the practical implications of philosophy derive from philo­sophical theories. An obvious and well-known example is Marxism, which is a philosophical theory that made great change in the world of political and economic practice. Unfortunately, some of these changes were for the worse; fortunately, not all of them were. Nevertheless, this is a different matter: after we agree as to what philosophy is and that it has practical implications, we may continue the discussion and find out under what conditions which practical implications of which the­ories are good, which are bad. So we should first take note of how Marxism - like many other theories - has practical implications, and then ask which of these are good and which are bad and why. Some may say that this is irrelevant because Marxism is not a philosophy but rather a science. This idea was common among followers of Marx during his lifetime and even later, but it is no longer popular. If one is tempted to cut things short, saying that philosophy has no good practical implications, we can likewise cut short the discussion and mention that some of the greatest and most influential ideas began as philosophical theories, including the ideas of the unity of humanity, equality before the law (isonomy), and democracy.

However, here we claim more: practical implications of philosophi­cal discussions are not limited to only politics or morality; they appear in many other fields, including science, technology, and even aesthet­ics. We return often to this very point, and we wish to dwell on the good implications rather than the bad because they are more interest­ing and more challenging: bad results are easier to achieve and less interesting than good results.

The History ofEpistemology

In a sense, philosophical discussions take place in every culture because almost everywhere people discuss the following and similar questions, which traditionally count as philosophical: How is life main­tained? How did it start? What happens after death? What is the good life? What is the good society? How is error to be avoided?

The last question, how can we avoid error, is the toughest of them all.

Usually, our culture is identified today as rooted in both ancient Israel and ancient Greece. The Greeks dealt with the following two questions that other cultures rarely discussed except under Greek cultural influences:

ι. What are the explanations for what regularly happens in the world? and

2. Howcantheoriesbeproved?

When discussing the first question, Greek philosophers eventually developed the theory that the physical world consists of four basic elements: earth, water, air, and fire. This theory is not unique to the Hellenic world; indeed, the Chinese also included wood. Either way, this theory is false, as every schoolchild should know. But it is a pow­erful theory nevertheless; to see its power, consider vegetation. Trees are the products of earth and water; watering the earth is necessary for growing plants; plants wither and then turn back into a type of soil or burn and turn into fire, air, and earth. This was just one theory; many others were present in ancient Greece. Discussions of the ques­tions that these theories came to answer were more common among the Greeks than among other peoples. More than a thousand years after the decline of ancient culture, its heritage gave rise to the diverse modern sciences that have propagated in other cultures with few or no traditional Greek roots.

Historians of culture have recently called the early modern period of Western history “the Renaissance,” meaning the rebirth of ancient culture, meaning the wish of thinkers and artists of that period to revive ancient culture. Their chief drive was the wish to revive antiquity on the supposition that the ancient world was superior. The Renaissance thinkers considered great only ancient art and writings on matters religious, philosophical, scientific, and - perhaps most important - political. The revival of the splendor of the ancient Roman Empire was Machiavelli’s only motive and the reason for his tremendous pop­ularity that overcame the smear campaign against him - perhaps the worst smear campaign in history.

This craving for ancient glory was not specific to the Renaissance though. The thinkers of the Middle Ages felt the superiority of antiq­uity even more profoundly, yet they did not expect to do much about it except wait for it with strong yearnings. The Renaissance thinkers had more self-confidence and more readiness to act, so their most important leaders were artists - architects, sculptors, and painters. Their poets and writers were much less influential.

The greater Renaissance thinkers soon discovered that the most important contribution of Greek culture to the world is the idea of intellectual and moral independence: think and do what you think right, not necessarily what your parents and teachers taught you. Exer­cising independence, they went beyond ancient Greek culture; when the Renaissance was over, it gave way to the Age of Reason. (Histori­ans usually consider the Renaissance to be the period between 1400 and 1600 and the Enlightenment Movement or the Age of Reason to be the period between 1600 and 1800.) In the Age of Reason, science flourished.

In one sense, this is the question to which every culture devoted much effort. Every culture we know is intent on self-preservation and, it seems obvious, this is only possible if not too many members devi­ate from the traditional culture. It seems equally obvious that this is possible only if deviation is viewed as error and error is avoided with much investment of energy - in education, preaching, and polic­ing. (In the Middle Ages and more so in the Renaissance, preaching was more effective than policing, and politicians took it very seriously, unlike today, when so many of us consider preaching an empty ritual.) The ancient Greeks were different: they did not think that following one’s own tradition is so obviously right. Many of their great thinkers preferred innovation to tradition. (Democritus, the great inventor of atomism, said that to discover a law of nature is better than to be the emperor of Persia.) Then the question arose: Who is a teacher worthy of attention? For clearly, when people disagree, some of them must be in error. Is disagreement necessary, then? Or is it possible to avoid error when presenting interesting ideas?

The field in which this question is discussed is epistemology. The word episteme was translated into Latin as scientia and into English as knowledge (also, the chiefly Scottish ken, as in “beyond my ken,” which is akin to the German kennen, “to know”). Since Plato and Aristotle, quite a few thinkers - from the time of ancient Greece to the time of Einstein and beyond - viewed science as the set of ideas that is absolutely free of all error. This was the standard view. Is error avoidance at all possible? This question is still under discussion to this day. It is one of the main questions that we discuss in this book.

Whether science in the sense of error-free knowledge exists is still in dispute. This sense is often confused with the sense in which science exists, and it is the business of the science faculty of most modern uni­versities. The confusion amounts to the claim that what the faculties teach is error-free, a claim that has undergone a splendid empirical refutation known as the crisis in physics around 1900. Before the end of the nineteenth century, the view became ever more popular that science is error-free, that scientific knowledge is knowledge proper. This had powerful political implications. Both science and modern industry are peculiar to the West. The conclusion was that the success of industry is due to the success of science so that social and political progress is inevitable. Industrial success made imperialism possible, and the set of ideas that went well with it brought about its philosophi­cal justification: the aim of imperialism was to civilize the whole globe. (The leading imperialist pundit of the time was the writer Rudyard Kipling; he called it “the white man’s burden.”) But this set of ideas was shattered with the evolution in physics in the early twentieth century. Many physicists then tried to return to religious tradition, as Russell sadly observed. In response, he and other rationalist philosophers said that even if science is not utterly free of error, its ideas are the best because they are the most probable. Itis one thing, however, to believe that a certain move in a game leads to good results more often than bad results and another to believe that a certain use of medication leads more often to the gym than to the graveyard (residence in the graveyard lasts too long for the possibility of repeating the procedure afterwards). This leads to interesting consequences, such as the moral dilemma involved in the use of immunization, which rescues millions and kills only a few. Should this return us to imperialism under similar justification? If not, why not? We return to this later in a subsequent chapter.

ErrorAvoidance and the Foundations of Knowledge

How, then, can one avoid errors? The first and default answer is, follow tradition. It is the oldest and, thus, older than all philosophy. The rejection of this answer is the beginning of philosophy; a philosopher may still decide to follow tradition but not as a matter of course. Most people do follow tradition as a matter of course; they are not philosophers. Another way to avoid error that is still rather simple is to say nothing and do nothing. This was the ideal of many traditions. The expressions of this idea are numerous and they permeate much folk culture everywhere. For example, if words are silver, silence is gold; and, both Chinese and Jewish sages say that inaction is preferable to action whenever possible.

Utter inaction is never possible: the truly inactive is truly dead. The wish to reduce action to a minimum, or the view that it is best, is not very satisfactory either. There is a traditional view that contrasts action with contemplation, and then it seems obvious that contemplation is the better option: many who work hard wish to work a little less so as to have time to observe and think. But this very contrast of action with contemplation is an error. Those who live by it often neither act nor contemplate. Rightly or not, traditional Western culture views research as a valuable form of action. This view and the traditional cultures that follow it all show interest not just in avoiding errors but also in right action, especially in the action of research that increases proper knowledge. We put great value on any explanation of the phenomena around us and in applying these explanations for the betterment of the human condition - and, because we cannot avoid thought and action, we want to do them as best we can. In other words, the epistemological question is: How can we present interesting ideas and act reasonably while avoiding or, at least, minimizing errors? Philosophers often consider this a task for the theory of knowledge, for epistemology.

Epistemology is relevant to the search for theories to explain observed events, especially repeated ones, and similarly to making judgments - practical, moral, political, or aesthetic. We return to this point in the following chapters because, in our opinion, humans are always prone to making mistakes. This idea seems to us so very obvi­ous that we would not have mentioned it, but then we are running against the whole of the tradition of philosophy with almost no excep­tion. The exception is so rare that it has a modern name: the great nineteenth-century American philosopher, Charles Saunders Peirce, christened it fallibilism.

It seems that here is an impasse: either we avoid errors and then whatever information or ideas we acquire is knowledge or we are for­ever ignorant. This is not so. For one thing, it may well be that we live in a world where fate grants knowledge only to those who dare to err. Folk wisdom manifested in innumerable folktales expresses exactly this idea. Or, we may take a risk and acquire information or ideas that may be true but with no guarantee; then the question is: How should we decide whether what we have acquired is the genuine arti­cle? These are obvious questions; we meet them regularly in practice. Does epistemology handle them? Does it then offer some practically valuable suggestions?

Because epistemology applies to all human activities, it may be inter­esting to ask: Where, if anywhere, was its application most obvious? As it happened, its first application was to philosophy, where it naturally was very problematic, and then to geometry, where it was considered the paradigm case.

Geometry has its place in every culture, but in Greek culture it had two characteristics that made it stand out. First, it had axioms and theorems deduced from the axioms, the way geometry is still taught in Western schools two and a half millennia later. It was one of the great­est Greek achievements because it was a case in which thinkers could say that they had overcome human fallibility. Greek geometry rests on the idea of proof, which is the second characteristic that is specifically Greek. To prove a theorem is to show that it logically follows from already proved theorems: whatever follows from what is provable is provable. But this leads to regression: theorem A is provable because it follows from theorems B and C, and B is provable because it follows from D and E, and so on. To stop the regression, some Greek thinker - probably it was Plato - invented the idea of axioms. In his view, an axiom is any simple, self-evident principle, sufficiently obvious to be in no need of proof. This is why Euclidean geometry allows the use of a ruler and a compass only: they are simplest, and the figures that they enable geometers to draw have obvious characteristics. For exam­ple, the idea that a straight line - drawn by an ideal ruler - goes on indefinitely in two directions is an axiom of Euclidean geometry. The circle - drawn by an ideal compass - has all points on its cir­cumference equally distant from its center, and that distance is its radius. Many bright high school students find it odd that their teacher ceremoniously tells them something so obvious as a straight line goes to infinity both ways and that a circle has a fixed radius. Teachers try to explain these axioms to these bright students, thereby making things worse, often with the result that the brightest drop out simply because their teacher cannot explain to them what is at stake; the teachers are familiar with the mathematics but not with epistemology. Also, they know how important axioms are for all mathematics, but this is too difficult to explain to students who have no mathematics at all.

Axioms are thus evident but not proven statements, and mathe­maticians state them in order to deduce from them other statements, thereby proving them. Thus, even if there is no need to state an axiom because it is so obvious, there is a need to state it as part of the mathematical process of proving theorems. Thus, all the theorems of a system follow from its axioms. But, as mentioned previously, the axioms themselves are not amenable to proof and are also in no need of it. This is why, traditionally, they were supposed to be obvious. (The situation in mathematics greatly changed in the nineteenth century.) Their being obvious presumably guarantees that they are true. Is that presumption true? Skeptics pointed at many cases where statements looked very obvious and then someone discovered their refutations, to everybody’s satisfaction. Skeptics used such experiences as evidence that no statement is immune. Today, most researchers agree that Einstein showed that Euclidean geometry is not certain because it predicts and explains repeatable observations less accurately than Einstein’s own geometry resting on the research of nineteenth-century mathematicians, notably Bernhard Riemann. Historically, doubt about the obviousness of a certain axiom opened the road to modern math­ematics, where obviousness is no longer required. This was the famous parallel axiom that states exactly one line is parallel to any other given line and also goes through any given point. Alternative geometries soon appeared that do not obey this axiom. Today, many mathemati­cians find it hard to explain why tradition viewed the parallel axiom as less obvious than Euclid’s other axioms. For example, the axiom that straight lines go to infinity in both directions may seem obvious to people with little training in geometry. Mathematicians say this is not so on a sphere, of course, and a sphere as big as Earth looks so much like a plane. They add that it is not obvious to them that the axioms of spherical geometry are not more obvious than those of plane geometry. However, and more important, they do not care. They study both plane and spherical geometry and ways of correlating them, and they are not concerned with what is obvious and to whom.

Back to our question: How is it possible to avoid errors without blocking the discovery of interesting ideas? Following the example of geometry, for ages, philosophers looked for statements that can function like axioms - that is, statements that are self-evident and can serve as the basis for more knowledge, perhaps even the com­plete set of axioms that would serve as a basis for all possible knowl­edge. Although mathematicians gave up the paradigm of this kind of research, there are still many philosophers who seek the self-evident axioms of philosophy.

What are the best axioms for the beginning of any scientific research? There are two alternative answers to this question, they are both very famous, and, as it happens, they are both impervious to any effort to apply them in practice. They are empiricism, the appeal to experience alone, and rationalism, the appeal to obvious abstract asser­tions alone. This terminology is troublesome because both empiricists and rationalists endorsed rationalism, the theory that states only what we can prove counts. So Kant suggested calling intellectualists the thinkers who rely on some obvious abstract assertions. The empiricists then claimed that the correct starting point for research is a set of reports of what the researchers themselves perceive. For example, “I see now a brown desk.” Somehow, this is not sufficiently simple. A desk is wooden, wood is made of God knows what, and there we go. Worse, we see the sun move across the sky, and Copernicus denied that it moves. Soon, the empiricists (John Locke, to be precise) preferred to discuss perceptions that they deemed more immediate, such as “I see now a brown surface.” Such statements, empiricists claimed, cannot be wrong, so they can serve as the starting point and the firm basis for knowledge.

The intellectualists suggested another kind of statement as the start­ing point for knowledge. They claimed that we should start by reveal­ing statements that we cannot imagine as false; that is, we should start not with the senses but rather with the intellect. Mathematicians, we remember, have used this method since Antiquity. For example, how many prime numbers between one and a hundred can be dis­covered by reasoning alone, without referring to the senses? However, the intellectualists claimed that this method is applicable not only to mathematics but also to statements about the shapes of things in the world. To continue this line of thought, Plato and Descartes said that knowing all about the shapes of things amounts to knowing all about them.

Skeptics need no specific information to object to both empiri­cism and intellectualism. Empiricism is erroneous, the skeptics claim, because our senses often deceive. If there is a criterion that sifts the true part of the information that the senses convey, then this criterion is imperfect. Moreover, even if we assume that sense data (datum = given) are certain, as Hume argued, they do not suffice for the construction of sufficient knowledge about anything in the world. Intellectualism is in error, too, the skeptics continue, and for similar reasons: we often err when we reason. If we use a criterion for the reliability of some thinking, as Descartes did when he declared clear and distinct ideas true, then this criterion is imperfect and not even sufficiently clear: What makes an idea sufficiently clear and distinct? Moreover, even if we assume that some (e.g., clear and obvious) ideas are certain, they do not suffice for constructing interesting knowl­edge about the world. In what follows, we reproduce some of these discussions, stressing the skeptical arguments.

Empiricism, intellectualism, and skepticism were already notorious in Antiquity, in the time of old Greek philosophy. (Old Democritus had a dialogue between the intellect and the sense, in which both par­ties lost.) At the beginning of the seventeenth century, the renewed discussions became the center of modern Western philosophy. Intro­ductory courses in philosophy, the philosophy of science, or early mod­ern philosophy usually summarize these arguments. However, these presentations tend to ignore the position of the skeptics as much as possible; by contrast, the skeptics occupy center stage in this work.

During the Middle Ages, the question under discussion (i.e., How can we minimize error?) had a simple and generally received answer: to minimize errors, follow tradition, because the Church knows the truth. This is the authority of tradition. In the sixteenth century, the Protestant movement undermined the authority of the traditional Catholic Church. At the beginning of the seventeenth century, Galileo, who was a mathematician and a philosopher as well as a devout Catholic, rebelled against the authority of the Church in matters intellectual and disproved the physics of Aristotle, whose texts univer­sity professors considered (almost) as infallible as the Bible. Galileo advocated Copernicus’ view that the earth moves around the sun, which is in the center of the universe, and he argued that the moon is not a perfect mirror (it has mountains, valleys, and seas) and that the sun is not perfect (because it has moving dark spots). He then demon­strated by reasoning^[3] alone that the speed of freely falling bodies does not depend on their weight - which was another break with Aristotle.

Philosophers then experimented with the idea of minimizing errors and advancing knowledge by the use of both reason and the senses. Intellectualism and empiricism then became the center of the dis­cussion. Unlike the ancient skeptics who were too aloof to seriously discuss the problems that science raises, the modern skeptics approve the use of both the intellect and the senses as a matter of course; however, being skeptics, they insist that neither carries any authority. It is, indeed, the search for an infallible source of knowledge that the intellectualists and the empiricists share, which is precisely the source of their disagreement: there can be no more than one infallible source because two can clash and then one should prevail. Therefore, as intel- lectualists always stressed, they never opposed the use of observations, but not as the final arbiter. The empiricists were less tolerant: ever since Sir Francis Bacon, they considered the use of theories danger­ous unless they are proven, and their proof rests on evidence. Hence, empiricists were opposed to all hypotheses: no matter how tentative one’s suggestion of a hypothesis, said Bacon, sooner or later one falls in love with it and then it becomes a dogma and interferes with one’s ability to see things as they are, thus disqualifying one as a researcher. This is empiricism, which we discuss later. The two schools share the idea that there can be only one final authority, so the strife between them continues indefinitely, revealing their good faith and keeping skepticism at bay.

Intellectualists suggest that the starting point should be thinking about the substances of the universe. A substance must exist; its nonex­istence is unthinkable. In other words, a substance is an entity the

existence of which is provable by rational means. Descartes claimed that the self is such a substance because I cannot imagine myself as not existing: even if I reject all of my views, I am left with my doubts; these are thoughts, and thoughts have a thinker. Just as a property must have an owner and a predicate must have a subject, thoughts have whatever that thinks them, and this item - whatever it is - is a person, and in this case it is the first-person singular, I. This is the idea in Descartes’ famous sentence: “I think, therefore I am” - which is a poor translation of his original Latin expression, cogito ergo sum - or, more grammati­cally, “I think, therefore I exist.” (The sentence became the slogan of an entire movement, the Enlightenment Movement, to designate the idea that the thoughtless hardly signifies.) However, Descartes’ main target was to prove the existence of God. (Although the philosophers opposed the Church as a reliable source of knowledge about nature, almost all of them were religious. The religion that is free of Christian­ity or any other Bible is deism, as distinct from theism, which relies on some Bible and resides in some religious organization.) God is a nec­essary substance, philosophers claimed, because - being perfect - He bears all the positive attributes, and being is such an attribute (existence of a good thing is nearer to perfection than nonexistence). This is the so-called ontological proof for the existence of God that was already famous in the Middle Ages; modern Western philosophers, including Descartes, Spinoza, and other intellectualists, improved and added to it their interesting elaborations. Immanuel Kant created a great stir when he declared invalid all proofs of the existence of God. He was not an atheist or even a skeptic, however. How he managed this feat is beyond our ability to explain. His refutation of the ontological proof was of great value for logic because he claimed that existence is nei­ther an attribute nor a predicate, which raised the question: What is it, then? This question was one that modern logic attempted to answer. It is still puzzling. But the ontological proof is so obviously invalid: as Russell said, if God exists because He is perfectly good, then so must the devil exist because he is perfectly evil. End of argument.

This is not the only flaw in the intellectualist plan for the construc­tion of knowledge. It is no surprise that it did not succeed. The surprise is that discussions about it were so fruitful and involved revolutions in logic, mathematics, physics, and even biology. The proofs for the existence of God were first to come under severe criticism. Modern logic goes much further by taking all demonstrable statements to be tautologies - that is, statements that are true by virtue of rules of gram­mar alone, rules that are valid simply because we have stipulated them. Hence, truths in logic are truths by convention, not truths by nature as was intended: no one wants God to exist just because we have agreed to use words and sentences this or that way. Moreover, the assertion that God exists does not lead to any interesting explanation.

The empiricists suggested an alternative. Again, they claimed that direct reports of sense data, what is given (datum = given) to our senses - being given by Mother Nature - are certainly true. This was Bacon’s adoption of a traditional Christian idea to methodology: all errors are due to our willfulness. The given is not due to our doing but to the doing of Mother Nature, so it cannot be faulty. (Here, Mother Nature is God.) Thus, according to Bacon, utter passivity secures free­dom from errors. When we sense our data in regular associations, we learn that data come in regular associations. (This idea played a tremendous role in psychology; it is called associationism.) For exam­ple, we regularly associate heat sensation in the presence of fire; we conclude that fire and heat come together, and then that fire is the source of heat. This kind of association is induction; applying it is induc­tive inference. We can avoid errors, the empiricists claimed, by limiting our thinking to what we can learn by proper induction from proper experience. Experience has to comprise careful observations; induc­tion has to be judicious. What all this means, however, nobody knows, except that both observation and induction must be cautious. How cautious should we be? When we see a smoking gun and a person dropping dead, may we assume that the cause of death is the shoot­ing, or should we wait for the autopsy? If so, then how careful should the autopsy be? And so on.

Hume made all these impossible considerations unnecessary when he refuted the theory by showing that causality is unobservable, no matter how careful our observations. No association, he concluded, can ever be certain. That the sun rose every day until now is thus logically insufficient grounds for the prediction that the sun will rise tomorrow as well. Of course, we do expect that the sun will rise tomor­row, he admitted, and even quite approvingly (we would dismiss him as mad otherwise) but not because past experience logically imposes it. Rather, it is the result of a psychological process that does indeed rest on our observations, but it is psychological, not epistemological. The long and the short of it is this: the prediction that the sun will rise tomorrow is not certain; therefore, it does not have the status of knowledge.

Here, Hume made a strange switch: he cast doubt on the certi­tude of natural laws and, hence, on their very existence, and then he replaced them with a psychological law on which he could cast just the same doubt. It is thus no surprise that the version of his philoso­phy that became standard is the extreme skepticism that he found so uncomfortable. That version takes both bodies and minds to be ways of associating data: a physical object is the collection of the set of data usually associated with a physical object, and a person is the collection of data usually associated with a person. On this view, only data exist. This is a strange view of that of which the world is composed. How­ever, in the Information Age, certain computer-inspired mechanistic ontologies have lent a certain new cachet to this view.^[4]

The next big idea was presented by Kant. He declared the situation scandalous and offered a totally new approach: he found a way to combine intellectualism and empiricism. His trick was to divide the domain among the different authorities so as to prevent all possible clashes among them. His view is thus a compromise or a synthesis: the intellect contributes theories, and the senses contribute infor­mative observation. The ideas that have no observational information with which to combine should forever be doubtful, and the wise should forever suspend judgment on them. Kant did not live by these ideas. For example, theology is a field that is too remote from both expe­rience and scientific theory, so one should suspend judgment in it. Yet, he said that we must assume God’s existence. We should overlook this inconsistency of Kant’s because it is intricate and irrelevant to the current discussion.

Like the intellectualists and the empiricists before him, Kant also attempted to defeat skepticism. He stated that everything “which bears any manner of resemblance to an hypothesis is to be treated as contra-band; it is not to be put up for sale even at the lowest price, but forthwith confiscated, immediately upon detection,” and he declared skepticism “the euthanasia of pure reason.” Kant claimed that the mind applies its own ways of thinking (its categories) to what the senses receive: this is how we think. Therefore, human knowledge is limited to mere appearances, not to the real, the things-in-themselves. Thus, there is no science from the viewpoint of eternity (to use Spinoza’s expression). All discussions of the thing-in-itself belong to metaphysics, a field that is doubtful; hence, it is to be avoided - better to have no metaphysical opinions. Among the contributions of reason, he listed not only the Euclidean theory of space and time and the idea that every event has a cause, he also listed the whole of Newtonian mechanics. He declared these to be the first and last word on their topics. Modern physics takes it for granted that Newtonian mechanics is not the last word and so it does not take Kant’s system as the last word either. Newton’s theory approximates some better theories and it is hoped that it approximates the truth. Of course, one may suggest other ideas but, as Kant’s contemporary, the philosopher Salomon Maimon pointed out, any suggestion about the scientific status of any theory would be another hypothesis, not a necessary truth and, there­fore, neither an item of knowledge nor a proper foundation. Thus, he was the first to draw the heretical conclusion that Newton’s theories as well are not certain. His skeptical reading of Kant’s structure keeps it intact but not as a foundation, thus undermining the very rationale for Kant’s efforts - and irremediably so.

Nevertheless, during the nineteenth century, Kant’s influence dom­inated epistemological discussions and brought about some false sense of security. With the crisis of physics in the beginning of the twenti­eth century, severe criticism brought it down. This time, the main attack came with the aid of some powerful developments in logic; declaring scientific truths not truths by nature, critics made it truth by convention and so not final. Indeed, the revolution in physics at the time raised a better alternative to the traditional views about scientific truth. Yet, wishful thinking had its day: the urge to anchor science in solid ground and attain finality won. In response, the logical pos­itivists declared all sentences meaningless unless claims accompany them about the way in which it is possible to verify or refute them by possible empirical observations. For example, a statement like “God exists” is meaningless because there is no way to verify or refute it; and “This desk is brown” comes with the claim that if you doubt it, you can have a look and judge for yourself. Whereas metaphysical utter­ances are meaningless, the logical positivists declared, scientific the­ories are verifiable or refutable by empirical observations. Later, they modified their view: scientific statements are also not really certain, they admitted, but merely highly plausible. Scientific theories are, then, generalizations of empirical observations. As long as they meet with no counter-examples, the higher the number of observations that agree with the theory, the higher the probability of the theory.

Under the severe criticism that Russell, Popper, and other philoso­phers launched against logical positivism, its adherents slowly moved away from the theory of meaning and, finally, shamefacedly relin­quished it. Because there are two components to logical positivism - a new one that has to do with meanings and a traditional one that has to do with the foundations of knowledge - the heirs to logical positivism are now mainly concerned with the traditional view of science as prob­ability. This is a premise for a new inductive logic. It is the suggestion that, given a set of data, whatever these are, and a set of theories, no matter where they come from, at least in some cases the calculus of probability permits data to render one theory most probable, even though not certain. This theory is currently all the rage, despite the refutations that Hume and Popper presented. We review the theory in the next chapter.

A Word about Metaphysics

This study has little to say about metaphysics. This is regrettable, because metaphysics is a major part of traditional philosophy. So much so, that the hostility to philosophy is often taken to be hostility to phi­losophy as such. This, of course is exaggerated, quite apart from the fact that hostility should have no access to philosophy. Metaphysics is usually considered the theory of the universe, and its major part is ontology, the theory of what there is. Now many physicists are seek­ing these days the theory of everything, a theory that will offer a full list of the elements of matter and of the forces of nature that should comprise an adequate explanation - whatever this is - of all that we know of the physical universe, perhaps even of the whole universe. This theory would be scientific. A theory was traditionally deemed scientific if it was certain and if it was explanatory. Traditional commentators discussed metaphysics only to the extent that philosophers claimed that it was certain, ignoring the uncertain (the speculative, to use the jargon word) such as all sorts of non-western metaphysics and all sorts of western religious metaphysics (including traditional theology). Yet there was no claim that metaphysics was explanatory. Thus, traditional atomism was deemed not explanatory and thus not scientific; perhaps it was deemed not even certain. As uncertain metaphysics was rejected, the advocates of any general view of the world had to declare their view certain. Thus, two theories of knowledge (epistemologies, to use the jargon word) competed, the one known as the a priori or inductive or empirical and the other as the a posteriori or deductive or intellec­tual. Needless to say, as sceptics we reject all claims for certitude, and as modern sceptics we do not reject either method of research, the empirical or the intellectual, and, following Popper we deem each a check on the other.

The traditional metaphysical theories divided all things between two categories, appearance and reality, where descriptions of appear­ances belong to empirical studies and the description of reality to explain them. This was never achieved. Moreover, the theories about reality were traditionally deemed theories about the one substance or the two substances that the universe really comprises. There is no need here to discuss theories of substance, and one example should suffice: ancient atomism: the world comprises atoms moving in empty space. This raises questions about the atomic structure of anything, from sticks and stones to souls and works of art. Whatever was not considered atomic was dismissed as mere appearances. The doctrine of substance was confused, and lost its popularity among those who respect modern logic, because under its impact it became clear that efforts to reconstruct it are hopeless. Before that, one of the most central questions of modern metaphysics was, are human souls sub­stantial - and so indestructible - or mere appearances? If the soul is real, namely, if it is a substance, is it inherently good or is it inherently evil? Apparently we are capable of good and of bad actions, but the question is not about appearances but about reality. Such questions still engage those who cling to traditional metaphysics as substance theory. They have thus given up the wish to be rational. So one of them declares that the substances that the human soul comprises are fear and boredom; another declares that it comprises fear and nausea. We will ignore all of them and leave the details of rational metaphysics for another day.