It’s the beginning of the semester, and we’re talking about the brain in my Introduction to Psychology class. “After all, the brain produces the mind,” I tell my students. “So if we want to understand the mind, we need to first understand the brain.” The class smiles and nods and accepts what I say at face value. But then, they’re naïve freshmen.

If the truth be told, we’ll rarely refer back to the brain later in the semester. We’ll cover the full range of topics in psychology—behavior, emotions, , development, social influence, , , even abnormal behavior and how to treat it. But in none of these areas do we really have a clear idea how the brain is involved.

Thanks to the development of brain imaging techniques such as fMRI over the last few decades, we certainly know a lot more about the brain now than we used to. Although scientists have been studying the brain for centuries, it wasn’t until they could watch it in action that they finally began to understand how it works.

“Most of what we know about brain functioning,” I tell my students, “has been learned within your lifetime.” And I’m not exaggerating. There are things I regularly teach now that weren’t even known when I was in graduate school.

As Seth Schwartz and his colleagues point out in a recent article in the journal American Psychologist, the tremendous advances in our knowledge of how the brain works has made the dominant field within psychology. The number of articles containing the term “neuro” in their title have increased exponentially over the last few decades. In part this is because it’s now quite difficult to get funding for a research program if it doesn’t include at least one study using brain imaging technology.

Jumping on the neuroscience bandwagon, psychology departments at major universities around the country have changed their names to include the buzzwords “Brain Sciences” or “Neuroscience.” In an informal survey of job postings in the APA Monitor, Schwartz and colleagues found that about half included “neuroscience” or a related term in the job description. It would appear that neuroscience is the future of psychology.

But what exactly is all the excitement about? The problem is that, unlike the natural sciences, psychology has no grand unifying theory (or GUT) that ties the whole enterprise together. The list of topics that psychology includes is vast, but it's not really clear what they all have in common.

The allure of neuroscience is that it may finally give psychology a GUT. This is because neuroscience is based on the premise that all psychological processes can ultimately be explained in terms of brain processes. This new hope for psychology has spawned a veritable neuro-zoo, as each sub-discipline now has its own neuro-doppelgänger.

We now have developmental neuroscience, affective neuroscience, clinical neuroscience, and even social neuroscience. Whatever flavor of psychology you prefer, you can always sprinkle a little neuroscience on top. Those in the rising generation of psychologists still in graduate school will find it difficult to get hired or get funding unless they know how to run subjects through an MRI.

But is it even true that all psychological processes can ultimately be reduced to brain functions? As Schwartz and his colleagues point out, it all depends on which brand of reductionism you subscribe to.

The position of constitutive reductionism states that brain activity produces all mental processes. In other words, mind is a product of the brain, rather than being some separate entity, such as a soul. There is wide consensus within experimental psychology that this is the proper stance regarding the mind-body problem.

However, there is a big difference between stating that the mind is a product of the brain and claiming that the mind is nothing more than brain activity. This second position is called eliminative reductionism. Neuroscientists who take this stance believe that eventually our understanding of the brain will be so complete that all other psychological theories will become superfluous.

Imagine a brain scanner so precise that it could read every thought your brain was producing in real time. Then the psychologist behind the scanner would know exactly what you were thinking as you were thinking it, and maybe even before you were fully aware of that train of thought. If eliminative reductionism is true, a full knowledge of brain states is all we need to know to explain human behavior.

Such a scenario may sound scary, but Schwartz and colleagues are skeptical that it will ever come to pass. Although they agree that the brain produces the mind, they don’t think that mind can be reduced to brain. This is because of a phenomenon known as emergence, which is widely observed throughout the physical world.

The classic example of emergence is water, which is a chemical combination of hydrogen and oxygen. There's nothing in the qualities of these two gases that would allow you to predict beforehand that they would chemically combine to form a liquid. Rather, liquid water emerges out of the chemical reaction of these two gases.

Examples of emergence abound in the natural world. Even in the early decades of the twentieth century, some biologists still believed in a "vital force” that animated all living things. But we now know that there is no such force. A cell is just a bag of chemicals, none of which are alive, but through the complex interactions of those lifeless chemicals, life emerges.

As so it is also with the brain-mind relationship. Not a single one of the hundred billion neurons that make up your brain is conscious. And yet, through the complex exchanges of chemical and electrical signals within the vast networks these neurons create, consciousness emerges.

Schwartz and colleagues also warn against what they called “neuroseduction,” which is the tendency to accept dubious claims when couched in terms of neuroscience. In one study, undergraduates judged logically-flawed reports of research findings to be more convincing when the phrase “brain scans show” was included. Likewise, the company Lumosity seduced more than 70 million subscribers with its "brain-training games" that were supposedly “based on neuroscience.” That is, until the FTC found the company guilty of false advertising and slapped it with a hefty fine.

Neuroscientists themselves are not as easily seduced. They do in fact understand that brain-scan studies only show correlations between brain states and mental states. As my students will be learning next week in the chapter on research methods, correlation does NOT imply causation. And correlation certainly doesn’t mean that one variable is reducible to the other.

In the first decades of the twenty-first century, neuroscience is “sexy” psychology. But Schwartz and his colleagues point out that we’ve been seduced before. At the turn of the twentieth century, and friends touted as the ultimate theory of the human mind. A few decades later, John Watson and B. F. Skinner promoted radical behaviorism as the enlightened path to a truly scientific psychology. Each had its heyday, yet neither unified the field.

Today, psychoanalysis and behaviorism are but two dishes to sample from the hundred-course smorgasbord we call psychology. In the next few decades, we’ll find out whether neuroscience is just another tasty entrée on the table, or if it’s the only item on the menu.