It's always best when mysteries can be explained in terms of things we know. But when we find this hard to do, we must decide whether to keep trying to make old theories work or to discard them and try new ones. I think this is partly a matter of personality. Let's call Reductionists those people who prefer to build on old ideas, and Novelists the ones who like to champion new hypotheses. Reduction- ists are usually right — at least at science's cautious core, where novelties rarely survive for long. Outside that realm, though, novelists reign, since older ideas have had more time to show their flaws.
It really is amazing how certain sciences depend upon so few kinds of explanations. The science of physics can now explain virtually everything we see, at least in principle, in terms of how a very few kinds of particles and force-fields interact. Over the past few centuries reductionism has been remarkably successful. What makes it possible to describe so much of the world in terms of so few basic rules? No one knows.
Many scientists look on chemistry and physics as ideal models of what psychology should be like. After all, the atoms in the brain are subject to the same all-inclusive physical laws that govern every other form of matter. Then can we also explain what our brains actually do entirely in terms of those same basic principles? The answer is no, simply because even if we understood how each of our billions of brain cells works separately, this would not tell us how the brain works as an agency. The laws of thought depend not only upon the properties of those brain cells, but also on how they are connected. And these connections are established not by the basic, general laws of physics, but by the particular arrangements of the millions of bits of information in our inherited genes. To be sure, general laws apply to everything. But, for that very reason, they can rarely explain anything in particular.
Does this mean that psychology must reject the laws of physics and find its own? Of course not. It is not a matter of different laws, but of additional kinds of theories and principles that operate at higher levels of organization. Our ideas of how Builder works as an agency need not, and must not, conflict with our knowledge of how Builder's lower-level agents work. Each higher level of description must add to our knowledge about lower levels, rather than replace it. We'll return to the idea of level at many places in this book.
Will psychology ever resemble any of the sciences that have successfully reduced their subjects to only a very few principles? That depends on what you mean by few. In physics, we're used to explanations in terms of perhaps a dozen basic principles. For psychology, our explanations will have to combine hundreds of smaller theories. To physicists, that number may seem too large. To humanists, it may seem too small.