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  That is what it means for truth and reality to be one and the same.

  Using Our Senses

  The second core assumption is that our senses—our eyes, ears, sense of touch, smell, and taste—perceive the external reality around us. Our eyes see a table because a table exists in reality. In theory, this is something we can never prove—that a table really exists or that an object that appears round is truly round. We have no other source of information about whether our perception is accurate.

  Bertrand Russell explored the relationship between our senses and reality in his book The Problems of Philosophy.9 We never perceive the world directly, Russell said—we perceive our sense-data, and they in turn perceive the world. The fact that our senses are forever standing between us and reality poses a problem because our senses can be misled by changing conditions or by our state of mind. A table that appears red in the morning can look brown at noon and purple at dusk. It can look huge in a small room and tiny in a cavernous one. Press on the table with your fingertips, and you’re not feeling the table—you’re feeling the sensation of your fingertips being compressed. Or at least you think you are, since any number of things can cause you to experience that sensation. Do you really know that a table is causing that feeling, or is it all in your mind?

  Maybe there’s no table there at all!

  Just about the time Russell has us doubting the existence of tables (and everything else), he rescues reality. Even if a hundred different people describe a given table in a hundred different ways, he reminds us, they can usually agree that they are in fact looking at a table. That common denominator suggests that our confidence in the table’s existence is justified, even if we can’t quite sort out the details of color, texture, and size. And even if we disagree on everything else, we can accept that it has these attributes—it has a color, a texture, and a size. And our senses, limited as they are, represent our best chance of discovering the truth about those attributes.

  Of course, in everyday life we take for granted the validity of what our senses perceive since we interact with the world all around us. This core assumption further implies that our only source for making assessments about what is true or not, what exists in reality and what does not, is our senses. To rephrase, if we can’t perceive something or its effects without the use of our senses, then we have no ability to evaluate whether or not it’s true.10

  It goes without saying that the ability of our senses to perceive reality can be greatly enhanced and extended through the use of tools, instruments, and technology. Millions of people see the world around them with better clarity and detail because of their eyeglasses or contact lenses. Scanning electron microscopes let us see tiny objects such as a single hair on the leg of a housefly. Ultrasounds can peer through the womb of a mother to reveal the developmental stage of a fetus. Radar can alert us of aircraft hundreds of miles away. The use of tools and instruments to derive knowledge about the world is commonplace.

  But all of these instruments have one crucial thing in common: they all translate their acquired information into a form that we can perceive through our rudimentary senses. It is still our senses alone that ultimately allow us to perceive what these instruments detect. We also rely on our senses to confirm the accuracy of these tools. Looking in the sky for an airplane can validate radar. Looking at the newborn child can confirm the ultrasound diagnosis.

  Of course, our senses are not infallible, in part because our minds interpret what we see and can therefore bias our perceptions. Still, aside from people who have mental disorders, what we perceive with our senses is generally accurate. For example, when one looks at a spoon that is placed inside of a glass of water it may appear bent. Although we know that the spoon is not really bent, but refracted, the observation that the spoon appears bent is an accurate reflection of what is real. The problem is not with the ability of our senses to observe reality but with the conclusions the mind may draw from what is seen. So if a person thought the spoon actually was bent, that would be a false conclusion based on a misinterpretation of good data. Our senses’ abilities to feel the spoon in the water confirm that it is indeed as straight as it was before it went into the glass.

  We will deal more with how we should process the information our senses receive and how to deal with conflicting information about what to believe later in the book. At this point it’s enough to say our senses are the only source for ascertaining what is real and what is not in the external reality (despite their deficiencies).

  The senses we are referring to include only the five rudimentary senses of sight, touch, hearing, smell, and taste.11 Why not include other senses such as a “sixth sense” (extrasensory perception) or the “heart” (intuition) as part of the list of senses that inform us about what exists in this world? We will deal with this issue more explicitly in forthcoming sections. For now, let’s see how much progress can be made by accepting only the five biological senses.

  Using Our Minds

  The last core assumption we propose is that language and thought are tools for describing and understanding what our senses perceive. The phrase “language and thought” will be used throughout the book to represent a broad range of more nuanced terms, including language, words, semantics, logic, mathematics, statistics, thought, mind, and intellect. This assumption requires us to think about words, definitions, and other concepts in ways that may be unfamiliar. But it is critical for the steps to come, so let’s take it slowly and break things down for better comprehension.

  Language, words, semantics, logic, mathematics, statistics, thought, mind, the intellect, and the like can be lumped together since they can be viewed as one and the same—tools used to communicate meaning. Such tools create necessary starting points for discourse, and their validity is rooted in their definitions. Consider language for a moment. In order to even ask the question, “How can one justify one’s beliefs?” there needs to be agreement on what the words belief and justify mean.

  Agreement is at the heart of language. Unlike physical reality, there’s no inherent “truth” about the meaning of a certain word, and there’s no universally right word for a given thing or idea. A word means what we mutually agree it means. Reality is independent of our ideas and perceptions of it, but language is entirely dependent on them. There can be many correct words for a single thing (hello, bonjour, guten tag, hola, shalom, néih hóu), and conversely a single sound can mean different things to speakers of different languages. The long i sound, for example, means eye in English, yes in Scots, and egg in German—each the result of subjective agreement in that culture.

  For another example of the nature of language, we can turn to the language of mathematics. The Pythagorean theorem asserts that the sum of the squares of the sides of a right-angled triangle equals the square of the hypotenuse. This is true not because there is some inherent wisdom in the assertion but because the definitions of sum, squares, equal, and triangle make that statement coherent. It may take the mind of a genius like Pythagoras to demonstrate some of the principles of mathematics, but the proof of the resulting theorem does not require a leap of faith—it just requires an understanding of how we have defined those terms.

  These definitional truths can further be used to describe real objects in the external reality—the length of a triangle drawn on paper can represent the measurement of an actual triangular object that exists in the world. Were we not to accept the validity of these tools, we would lack an ability to form any thoughts, concepts, or principles based on what we observe through our senses.

  This core assumption in definitional truths also includes the use of our minds and intellect to manipulate and process thoughts and data. The power of our mind allows us to define language and objects, manipulate numbers, and develop rules. By accepting the validity of this assumption, we also accept the use of language and thoughts to derive other facts and information that may not initially be clear to us. We can
then use these conclusions to reflect back on the external reality. This ability to switch between reality and our description of reality allows us to formulate far more sophisticated concepts and notions than just simple observations. So part of the acceptance of this assumption means also accepting the ability of our minds or intellects to organize thoughts, to find links between thoughts, and to draw conclusions.

  The First Three Non-commandments

  Where does accepting these three basic assumptions really get us? After all, most of us accept these notions in our everyday lives without feeling the need to explore all their nuances.

  But here’s why they are so important: from these three assumptions alone, it’s possible to derive many, many more beliefs. These assumptions and derived beliefs will help us formulate a framework of beliefs, including Ten Non-commandments for the Twenty-first Century.

  The commonsense nature and seeming simplicity of these assumptions allow us to accept them at a glance. But that very simplicity might be mystifying. Can these three assumptions really be all we need to justify our beliefs? Hang on to that question, and we’ll see soon enough.

  To rephrase the three core assumptions in light of the concepts we have just discussed, our starting assumptions are:

  An external reality exists, and “truth” signifies an accurate description of that reality.

  Our five senses are our only means for perceiving this reality.

  Language and thought offer ways to analyze, communicate about, and contemplate the nature of the reality.

  These core assumptions can be summed up as (1) a belief in existence, (2) an ability to perceive that existence, and (3) instruments for using those perceptions.

  There’s still some work to do to determine whether these three core assumptions are really all we need. For one thing, we need to see what other beliefs can be derived from these assumptions and test whatever system of belief arises from them. Only when we have a complete, tested system can we be satisfied that our initial assumptions are sufficient. For now, to keep things moving forward, we only ask that you give us the benefit of the doubt that the beliefs being proposed will yield a valid outcome. There’ll be plenty of time to change your mind if you so choose.

  Because these three assumptions are the bedrock beliefs of all subsequent beliefs we will propose, they will serve as the first three non-commandments:

  I.

  The world is real, and our desire to understand the world is the basis for belief.

  II.

  We can perceive the world only through our human senses.

  III.

  We use rational thought and language as tools for understanding the world.

  (For a point-by-point distillation of the concepts presented in this chapter, as well as subsequent chapters throughout the book, we invite you to turn to appendix C, “Theorem of Belief.” This appendix summarizes the flow of arguments and the links between the various ideas that are presented. It is the intellectual bones of the book laid bare.)

  3

  The Reasoning behind Reason

  Experience is a hard teacher because she gives the test first, the lesson afterward.

  —Vernon Law

  What further beliefs can be derived from the three core assumptions? The most significant is the belief in inductive reasoning. To formulate this belief, we can use two of the core assumptions: confidence that our senses reflect reality and acceptance of the language of mathematics.

  Inductive reasoning refers to the concept of drawing broad conclusions from specific observations or experiences. Let’s look at a simple example. Most of us saw the sun rise today (or at least saw that it had risen).1 We saw it the day before as well. We have seen it rise on many, many occasions before that. In fact, most of us would have no recollection of a day completely devoid of sunlight. So if we’ve observed a daily occurrence many times without exception, probability tells us that the chance of it happening again tomorrow is extremely high. In other words, it’s reasonable for us to expect that the sun will rise again tomorrow.

  Of course, as philosopher David Hume pointed out almost three centuries ago, a reasonable expectation isn’t the same as certainty. Despite a track record of more than a million consecutive sunrises in recorded human history, there’s no way we can be absolutely certain the sun will rise tomorrow. Many a chicken waddles around day after day feeling confident—cocky, you might say—that it will waddle again tomorrow. But little does the chicken know that tomorrow may bring plucked feathers and a farmer’s cooking pot.2 So, no, we can’t be sure about the sunrise. What we can say is that based on our previous experiences, the chance that the sun will rise tomorrow is extremely probable, even if we understand that someday the sun will implode and go supernova—putting a definitive end to sunrises on Earth.

  Confidence in Beliefs

  Since beliefs are derived from prior beliefs, statistically speaking, a derived belief necessarily has less credibility than the belief it’s derived from. Conversely, the closer a derived belief is to a source belief, the more credibility we can give it, and the greater confidence we can place in such a belief. For example, we can believe things confirmed by our senses more readily than things only confirmed by the observations of others. That’s why “I’ll believe it when I see it” is one of our oldest statements of skepticism.

  The use of the phrase “confidence in a belief” may seem odd, since most people intuitively think that you either believe a proposition or you reject it. It’s a fact or it’s not. After all, didn’t we just argue that an external reality exists? While the truth is an absolute, our ability to assess that truth is not. We’re all fallible beings with different observations and experiences, and we can’t be sure about the complete validity of each belief. We can use statistics to help decide how much confidence we should have in each belief, attaching a probability to each belief to capture the degree of our uncertainty.3

  To get a better idea of how assigning probabilities to beliefs can work, let’s return to the sunrise. Isn’t our belief that the sun will rise tomorrow also based on the absence of any reports by any person—ever—of the sun failing to rise? Isn’t it also based on Newton’s theory of gravity and Kepler’s laws of planetary motion? All of these complement our belief that the sun will rise tomorrow, so we can add them to our own observations to drive the probability even higher. We can also note that inductive reasoning (reasoning that seeks evidence to increase confidence in a conclusion) is at the heart of each one of these beliefs.

  Let’s take a look at each of these sunrise confidence boosters.

  We’ll begin with the testimony of others throughout history who have seen the sun rise without fail. To decide whether or not to believe a particular source, we can evaluate whether or not that source has generally told the truth in the past. A belief in inductive reasoning gives us confidence that someone who has been an accurate source in the past is likely to be an accurate source on similar matters in the future.

  We all have years of experience evaluating which sources of secondhand testimony are reliable, so we naturally keep a mental list of sources that we trust as well as those we do not. So, if we need to know what happened in the Franco-Prussian War, we’ll put more confidence in textbooks and peer-reviewed published articles than the opinion of Aunt Mildred. That doesn’t mean the publications are perfect or that Aunt Mildred is a pathological liar. It just means our experience leads us to expect more reliable information on that kind of topic from the former than from the latter. If the topic was Uncle Jack’s snoring, Aunt Mildred would be the more reliable source.

  That leads to a follow-up question: should you put more confidence in your own beliefs or in the beliefs of other people? Does the fact that you’ve seen the sun rise so many
times outweigh historical records testifying to the same thing?

  It’s an interesting question. When assessing someone else’s testimony, especially over the span of years, you have to accept more links in a chain of beliefs than with your own observations. In general, the closer a belief is to a core assumption, the greater statistical credibility it has. That’s because the closer it is to a bedrock assumption, the more likely it’s true. Believing in one’s own observations only requires a belief in one’s own inductive reasoning, but believing in the testimony of others requires believing that they really saw the event and are giving an accurate account. A detective will tell you that eyewitness testimony is often as varied as the number of observers. The Innocence Project reports that nearly three out of four convictions that are eventually overturned by DNA testing included eyewitness misidentification.4

  The statistics can get far more confusing. Imagine a thirty-year-old woman named Caroline who lives in California. Caroline will have consciously seen the sun rise for about ten thousand days in a row. Statistically, based on Caroline’s personal observations alone, the probability that the sun will not rise tomorrow is about 1 in 10,001. But what if we accept instead the collective testimony of everyone who has lived in the last two thousand years? Suddenly, the chance the sun will not rise tomorrow is about 1 in 500 trillion.5 So even if Caroline decides to attribute less weight to the testimony of others, the incredible consistency of their data in this case lends enormous weight to her own observations.