Chapter 3.                              (continued)

Even the terms contained in natural law statements are vulnerable to attack by the skeptics. Hume argued more than two hundred years ago that we humans can’t really know that any of the laws we think we see in nature are absolutely true because when we state a natural law, the terms we use to name the objects and events we want to focus on exist only in our minds. A simple statement that seems to us to make sense, like the one that says hot objects will cause us pain if we touch them, can’t be trusted in any ultimate sense. To assume that this “law” is true is to assume that our definitions for the terms hot and pain will continue to make sense in the future as they have in the past. But we can’t know whether these assumptions will hold in the future. We haven’t seen the future. Maybe, one day, people won’t feel pain.

Thus, all of the terms in natural law statements, even terms like galaxies, protons, atoms, acids, genes, cells, and so on, are fabrications of our minds, terms that we create because they help us to sort and categorize our sensory experiences and memories of sensory experiences and talk to one another about what seems to be going on around us. But reality does not contain things that are somehow naturally fit as atoms, cells, or galaxies. If you look at a gene, it won’t be wearing a name tag that reads “Gene.” In Somali, it is called “hiddo”.   

Right from the start, our natural law statements must gamble on the future validity of our current mental categories—that is, our human-invented terms for things. The terms can seem sound, but they are still gambles, and some terms that humans once gambled on with great confidence turned out later, in the light of new evidence, to be naïve and inadequate.

 

                                                                           Isaac Newton.

Isaac Newton’s laws of motion are now seen by physicists as being useful, low-level approximations of the subtler, relativistic laws of motion formulated by Einstein. The substance called phlogiston once seemed to explain all of chemistry. Then Antoine Lavoisier did some experiments showing phlogiston didn’t exist. On the other hand, people spoke of genes long before microscopes that could reveal them to the human eye were invented, and people still speak of atoms, even though no one has ever seen one. Some terms last because they enable us to build mental models and do experiments that get the results we predicted. For now. But the list of scientific theories that eventually “fell from fashion” is very long.

 

                                                                       Antoine Lavoisier.

Various further attempts have been made in the last hundred years to nail down what scientific thinking does and to prove that it is a reliable way of knowing, but they have all come with insoluble conundrums of their own.

The logical positivists, for example, tried to bypass Hume’s problems with the terms in scientific laws and to place the burden of meaning and proof onto whole propositions instead. A key point in the logical positivists’ case is that all meaningful statements are either analytic or synthetic. Any statement that does not fit into one of these two categories, the positivists say, is irrelevant noise.

Analytic statements are those whose truth or falsity is determined by the definitions of the terms they contain. For example, “All bachelors are unmarried men” is an analytic statement. If we understand the terms in the sentence we can immediately verify, by thinking it through, whether the statement is true.

Synthetic statements are those whose truth or falsity we must work out by referring to evidence found in the real, empirical world, not in the statement itself. “All substances contract when cooled” is a synthetic statement—not quite a true one, as observations of water and ice can show. So is “If a creature is a whale, then it is a mammal.”

The logical positivists aimed to show that discussions between scientists in all disciplines can be made rigorously logical and can therefore lead us to true knowledge. They intended to apply their analytic–synthetic distinction to all statements in such a rigorous way that any statement made by anyone in any field could be judged by this standard. If the truth or falsity of a statement had to be checked by observations made in the real, material world, then it was clearly a synthetic statement. If the statement’s truth value could be assessed by careful analysis of its internal logic, without reference to observations and measurements made in the material world, then the statement was clearly an analytic statement. Idea exchanges that were limited to only these types of statements could be logically sound. All other statements were to be regarded as meaningless.

The logical positivists argued that following these prescriptions was all that was needed for scientists to engage in logically sound discussions, explain their research, and size up the research of their fellow scientists. This would lead them by gradual steps on to true, reliable knowledge of the real world. All other communications by humans were to be regarded as forms of emotional venting, empty of any real content or meaning.

                                   

                                                                                 Rudolf Carnap.

Rudolf Carnap, especially, set out prove that these prescriptions were all that science needed in order for it to work and to progress in a rigorously logical way toward making increasingly accurate statements about the real world—generalizations that could be trusted as universal truths.²

                                  

                                                                                Willard V.O. Quine.

But the theories of Carnap and the other positivists were taken apart by later philosophers such as Willard Quine, who showed that the crucial positivist distinction between analytic and synthetic statements was not logically defensible. Explaining what makes an analytic statement (e.g., “All bachelors are unmarried men”) analytic requires that we first understand what synonymous terms like bachelors and unmarried men are. But if we go into the logic carefully, we find that explaining what makes two terms synonymous presupposes that we first understand what analytic means. In short, trying to lay down precise rules for defining the difference between analytic statements and synthetic ones only leads us to reason in circles.³

  

Quine’s reasoning, in turn, was further critiqued and refined by later philosophers like Hilary Putnam. As Putnam eventually put the matter:

“… positivism produced a conception of rationality so narrow as to exclude the very activity of producing that conception” and “… the whole system of knowledge is justified as a whole by its utility in predicting [future] observations.”⁴

In other words, logical positivism’s rigid way of talking about thinking, knowing, and expressing ends up in a logically unsolvable paradox. It creates new problems for all our systems of ideas and doesn’t help with solving any of the old problems.