Readjust your liberal brain

The recent heartbreaking events in Virginia remind me that the way our brains work has its downsides.

Nervous systems love contrasts, thrive on them. It’s one reason why your brain does fancier things than your liver. For example, there are both excitatory and inhibitory neurotransmitters, so that the brain never confuses hollering “yes” with hollering “no,” or “go” with “stop.” There are also on-off cellular mechanisms that cause neurons to go sharply silent after a burst of excitation, generating a contrast like the difference between shouting news and shutting up. Or in another neural realm: Touch a spot on your skin, stimulating a tactile receptor neuron there, and it silences the tactile neurons surrounding it — sharpening the signal to identify precisely where the sensation is happening.

Crucially, the range of contrasts can change — sometimes the brain must distinguish between extremes of, say, 1 versus 100, but sometimes the extremes range only from 1 versus 1.00001. And brain processes shift to accommodate that.

For example, your brain typically navigates sounds ranging from silence to sirens, but huddle among people whispering, and soon your brain is detecting minute differences in decibels. Sit in dim light, and your brain soon distinguishes among tiny gradations of light intensity. Leave that dark room, where you’re distinguishing between 1 and 1.00001, so to speak, and go into sunlight: Things will shift back to 1 versus 100. Sometimes the range of what counts as pleasurable maxes out with the smell of a flower, sometimes it requires winning the lottery.

And thanks to that neural capacity for adaptation, sometimes the difference between 1 and 1.00001 can feel roughly as important as the difference between 1 and 100.

Many on the left have been concerning themselves of late with debates that can be summarized as 1 versus 1.00001. A professor, long supportive of his school’s efforts at fostering diversity, objects to one proposed version of those efforts, and soon crowds of students are accusing him of the worst kinds of prejudices, chanting for his firing.

A theater director, with the best of progressive intentions, mounts a play that showcases what she advocates. Soon she is condemned for deigning to present material about the tribulations of an out-group not her own.

Controversies roil as to whether a painting that screams empathy for the pain of an Other represents homage or exploitation, whether a fashion statement is cultural appropriation or appreciation, whether the best response to a foul academic ideologue is to attend his lecture and counter him with facts, or to silence him.

These are valid issues, and their currency reflects the left’s admirable ability to be introspective. But these debates also display the left’s time-honored capacity to eat itself alive with turmoil over the difference between 1 and 1.00001.

And then along comes Charlottesville, and we are reminded about just how contrasting contrasts really can be, how vast the difference between 1 and 100 is, or in this case, 1 and negative infinity. We are reminded what it is like when KKK garb, swastikas and torches are marched through our streets. What it is like when one of the marchers floors a car’s accelerator to hurtle into a crowd, leaving Heather Heyer dead. What it is like when, 70 years after 407,000 Americans died fighting Nazism, fascism and racial supremacy, we have a president who gives comfort to those malignancies. We are reminded what evil actually looks like.

If we readjust our brains to focus on the biggest of contrasts, then we can remember what the real enemy is, and use our intellect and passion to destroy it.

Neuroscientist Robert M. Sapolsky is a professor of biology, neurological sciences and neurosurgery at Stanford University. His latest book is “Behave: The Biology of Humans at Our Best and Worst.” He wrote this for the Los Angeles Times.