Jonah Lehrer looks inside fMRI machines:
Time and time again, an experimental gadget gets introduced -- it doesn't matter if it's a supercollider or a gene chip or an fMRI machine -- and we're told it will allow us to glimpse the underlying logic of everything. But the tool always disappoints, doesn't it? We soon realize that those pretty pictures are incomplete and that we can't reduce our complex subject to a few colorful spots. So here's a pitch: Scientists should learn to expect this cycle -- to anticipate that the universe is always more networked and complicated than reductionist approaches can reveal.
...Karl Popper, the great philosopher of science, once divided the world into two categories: clocks and clouds. Clocks are neat, orderly systems that can be solved through reduction; clouds are an epistemic mess, “highly irregular, disorderly, and more or less unpredictable.” The mistake of modern science is to pretend that everything is a clock, which is why we get seduced again and again by the false promises of brain scanners and gene sequencers. We want to believe we will understand nature if we find the exact right tool to cut its joints. But that approach is doomed to failure. We live in a universe not of clocks but of clouds.