How Do You Know?
On physics, metaphysics, and philosophy at UVA
© Photo by Ariel Bregman
The other day, I diagnosed a patient with depression and wrote her a script for Lexapro.
How does it work? she asked.
It increases serotonin, I said.
And how does serotonin work?
Well, it binds to receptors in the brain.
Oh. Cool. Where?
So, the amygdala, the hippocampus, and the prefrontal cortex.
And how does that improve my mood?
It just does, I said. It’s related. Higher levels of serotonin are associated with improved mood.
Silence. This was going nowhere fast.
Look, I said. As to the exact chain of cause and effect, I’ll admit we don’t understand much about that. Let’s just see if it works for you….
When I was a young medical student I remember observing a doctor with a patient who asked her one too many questions. Just take the pill! the doctor finally exclaimed, rolling her eyes.
I’ll never be like that, I said to myself at the time. And, in fact, I am pleased to report that I controlled myself and did not roll my eyes.
Besides, to be honest, my patient was right. Most of what we think we know in medicine is more mnemonic than truth.
We notice a possible cause and effect. Is it reproducible? If so, we call it evidence-based. If not, we call it chance. How it works matters less than if it works.
Last month, Rachel and I visited our son, Ariel, who is a sophomore at the University of Virginia. It was Parents Weekend and, to my great delight, he invited me to sit in on his Philosophy of Religion class review session.
He introduced me to the grad student teaching the session, who was named Dakota, same as our dog. I somehow managed to resist remarking on this amazing coincidence, much to Ariel’s relief.
Dakota walked the class through a discussion of determinism and free will. Are they compatible or incompatible? In a universe ruled by physics - which includes our brains - is everything predetermined by causal chains, or is there room for free choice?
In the end, everyone agreed that there is no free will. At least, not according to the laws of physics. And, by the way, in case you’re interested, that’s true even for quantum physics, where things occur by chance.
I looked around the room. None of the students seemed the least bit perturbed. And not because they weren’t paying attention. In fact, I was impressed by the diligent note-taking. Maybe it was Adderall or the upcoming test - maybe it was both.
Meanwhile, I was perturbed. After all, it seems to me that without free will, our world becomes unrecognizable. Without free will how do you get to morality? Freedom? Good and evil? How do you get to love?
If there is no free will - if all of our thoughts and actions unfold as predictably as a chemical reaction - then what’s the difference between a human being and ChatGPT? And if there is no difference, then how is taking a human life any worse than unplugging a machine?
I chose not to share all this with Ariel. I didn’t want him to regret inviting me to class. I just wanted to help him pass the test - which, I’m proud to say, he did - with flying colors.
As for me, I consoled myself with the following three thoughts.
One, perhaps the exact mechanism doesn’t matter for free will any more than it does for serotonin. They work, therefore they are.
Two, granted that a world of metaphysics cannot emerge from a world of physics, but what about the other way around? Maybe a world of physics can emerge from a world of metaphysics. Like the chicken and the egg. Which came first, God or the universe?
I ran the idea by Peter, my friend from medical school, who also happens to be a philosophy professor. If I understood him correctly, the argument is sound (or at least, begrudgingly, not unsound).
Three, worst case scenario, let’s say we discard freedom, love, and goodness as mere illusions that don’t truly exist - well, what of it? Maybe that’s OK - as long as we preserve the existence of Lexapro.
Fascinating to bring into one discussion the concept of free will (which dates back to the 4th century BCE and Aristotle) and the diagnosis of depression (which is more recently--the 19th century and Kraepelin). Both have been the subject of many discussions, with some range of views. I completely undertand that we don't know how they operate at the level of brain physiology or neurochemistry. But stating that is a bit like saying that we don't know how every atom in a car contributes to its ability to move...what EXACTLY is the friction between the tire and the road, how EXACTLY does combustion work, etc.? And let's not forget that the primates that we descend from never had to operate equipment like a car., so we are adapting old mechanisms to new purposes. We have different scientific specialties that are advancing on all of these questions, and engineers and technicians who apply these specialties to produce new cars. [I hope that we get good policies to reduce emissions and road fatalities as well.] Wonderful to ponder these mysteries: and an oppoortunity as well for gratitude for the human capacity to develop specific realms of knowledge and to coordinate with other realms of knowledge. Let us hope that it is for progress, for the well-being of individuals, society and our planet.
I think about Spinoza and free will all the time. Especially now in this period of political insanity. But I also think love is a verb and a choice that we humans make. Every day. So I, with my free will, choose to believe that there is both free will, in some instances, and, more often, a lack of it. Depends on the situation. And, as you know well, when you prescribed Lexapro after my father's death, it was a life saver. Then, when I weaned myself off after a year, you prescribed yoga. Also a life saver. You are an amazing physician and thinker, and we are all lucky to know you. Maybe YOU are the puppet master? Something to think about.