An excerpt from a terrific post by Jonah Lehrer, Clocks and Clouds:
Functional MRI has been used to study all sorts of sexy psychological properties. You've probably seen the headlines: "Scientists Discover Love in the Brain!" and "This Is Your Brain on God!" Such claims are often accompanied by a pretty silhouette of a skull, highlighted with splotches of primary color. It's like staring at a portrait of the soul. It's also false. In reality, huge swaths of the cortex are involved in every aspect of cognition. The mind is a knot of interconnections, so interpreting the scan depends on leaving lots of stuff out, sifting through noise for the signal. We make sense of the data by deleting what we don't understand.
...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.
Read the entire post here.