A Note About Evidence

There is a reason I use phrases such as fairly convinced and mostly convinced throughout this book.

I am trying to be precise.

I can be passionately behind an idea without pretending it has been proven. I can look at clinical observations, neuroscience, longitudinal patterns, sports psychology, individual cases, treatment responses, and my own years working with ADHD kids and become mostly convinced that an explanation is correct.

Mostly convinced still leaves room for me to be wrong.

You will almost never see me use the word believe when discussing a scientific claim. You will see the word proof even less. If I tell you something has been proven, the evidentiary bar is going to be extraordinarily high.

Part of that comes from the way I think about science. My standard for proof is much closer to the natural sciences and physics than it is to the standard routinely available to psychology and behavioral science. Human beings are extraordinarily difficult experimental subjects. We cannot control their histories, environments, genetics, sleep, trauma, relationships, hormones, expectations, cultures, or the thousands of experiences that occurred before they walked into a laboratory.

And we still cannot watch the living human brain work at anything approaching the resolution we ultimately need.

Someday, I expect we will be able to scan a living human brain at something approaching the individual cellular level while simultaneously observing the chemical processes occurring within it. When that happens, chapters of psychology will be rewritten. Some ideas that have survived for decades will become stronger because we will finally be able to see the mechanisms underneath them. Others that currently enjoy broad consensus may be substantially revised or thrown out entirely.

A lot will stay.

A lot won’t.

I don’t know which is which, and neither does anybody else.

That uncertainty is not an argument against psychology. It is an argument for humility about what our current instruments allow us to know.

That is why this book contains testable predictions. When I propose something that has not been established, I want to tell you that. When the evidence moves me strongly in one direction, I will tell you that too: fairly convinced, mostly convinced, strongly supported, consistent with the evidence. Those phrases are not rhetorical escape hatches. They are estimates of where I think the evidence currently points.

Then I want somebody to test the prediction.

Maybe I am right. Maybe I am wrong. Maybe I have identified the pattern correctly and completely misunderstood the mechanism underneath it. Maybe a distinction I think matters will disappear when better instruments arrive, or something I have grouped together will turn out to be three entirely different processes.

Good. Science is allowed to change my mind.

The purpose of this book is not to win an argument. It is to put observations, patterns, hypotheses, and predictions on the table clearly enough that somebody else can try to break them. If they survive, we learned something; if they break, we learned something.

Either way, run the experiment.