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A huge chasm separates philosophy from neuroscience. Philosophers rationalize about the essence of “desire”, “fear”, “morality”, and “consciousness” as if they are universal truths hidden within the logic of the universe. To a neuroscientist, however, they are just words that we made up to describe the result of a bunch of neurons firing in our brains.
It makes little sense to rationalize about these jumbles of neurological intuitions. That is what I believed: rationalizing about “morality” and “meaning of life” is futile because these concepts are defined by our neurological intuitions, which are vague, fuzzy, and different for each person.
But this is not true for all concepts. Some philosophical concepts can be rigorously defined on neurological basis. We can grind these abstract intuitions down to concrete neural circuits. And rationalize about them. And use them as the basis for defining other human concepts.
Tendency, Habit
Your brain is a deterministic machine. If you configure all your neurons into a certain state, they always respond by firing in the same pattern and cause you to do the same thing. It’s a habit: you see a chocolate bar sitting on the table → the visual information activates your chocolate bar neural circuit → you grab it, and chug it into your mouth.
Every time you activate your chocolate bar neural circuit, it gives you a tendency to grab the chocolate bar and munch it. Neural circuits are like little programs in your brain. Each time you activate a circuit, it causes you to execute a certain sequence of actions (unless a different circuit overrides it).
Having a tendency to do X is different from desiring X. When you wake up every day, your “morning routine” circuit is activated. You stumble into the bathroom and start brushing your teeth. Just because you have a habit of brushing your teeth does not mean you desire to.
Desire, Pleasure, Good, Dread, Pain, and Bad
Desire involves pleasure. You want to munch a chocolate bar because it gives you a fuzzy feeling called “pleasure.” The chemicals on the chocolate bar stimulate your taste buds, which induces your brain to release dopamine. And dopamine is a chemical that produces the feeling we call “pleasure.”
But why do we want dopamine? In other words, what makes “pleasure” “desirable”?
To understand, we must abandon the subjective illusion of “want” and “pleasure.” Take your brain out of your skull and imagine yourself as an alien scientist studying human behaviors. To you, humans are just biological machines executing programs (neural circuits) in their brain.
When humans execute the program of putting chocolate into their mouth, they continue executing it, and will execute it again in the future. When they put acids into their mouth, they halt the program immediately, and will never execute it again.
When a program causes the release of dopamine (pleasure), the chemical reinforces the neural circuit. Hence, the very concept of “pleasure” can be defined by its ability to reinforce a habit: eating chocolate is pleasurable precisely because it triggers the release of chemicals (dopamines) that increase our tendency to eat chocolates.
The concept of desire is the opposite side of the same coin: we desire chocolate because eating it causes a chemical response that makes us more likely to eat chocolates in the future.
“Desire” and “pleasure” are human concepts. In the physical reality they don’t mean much. The human brain is just a bunch of neural circuits. Some activities strengthen their own neural circuits, increasing our tendency to do them—we define these activities as “pleasurable” and we denote our tendency to perform them as “desire.”
We don’t “want” pleasure. Pleasure is an addictive chemical that reinforces our tendency to pursue it. A nuclear fission reaction does not “want” to explode. It’s just that each fission reaction increases the probability of a new fission reaction. Both are self-reinforcing loops. The very concept of “want” is bogus. To want anything is just to have a neurological tendency to do this thing. And its completion strengthens our tendency to do it again.
This defies our intuition. Intuitively, we understand “pleasure” as that fuzzy feeling—pleasure is just something that feels “good.” Well, the concept of “good” as we intuitively understand it, is also bogus.
“Good” and “bad” are ingrained into western philosophy as some sort of universal concept. Of course, “good” and “bad” are not universal truths written into the laws of physics. They are not even personal truths. The concepts of “good” does not exist. It is a subjective illusion like “pleasure” and “desire.”
Suppose I ask you why is that fuzzy feeling produced by dopamine “good”? What distinguishes something good from something bad is that you want the former and dread the latter. “Good” and “want” are two sides of the same coin. “Good” = “want” = “desire” = “pleasure” (one can argue there is a subtle difference between “good” and “pleasure” because the latter is commonly used to mean more immediate gratification; but they have similar gists).
The fuzzy feeling of dopamine feels “good” because you “want” it. You “want” it because the chemical that produces it reinforce your tendency to pursue it.
I am defining the word “desire” in a way that is a bit different from common sense. Two components determine the strength of a neural circuit: the strength of the circuit and the strength of its activation stimulus. The former is a more permanent artifact—a persistence inclination to execute a sequence of actions. The latter is an immediate “urge,” induced by hormones, the environment we are in, and the entirety of our mental state. Although in common sense, “desire” and “urge” are often confused with each other, I am using the word “desire” to refer to the persistent inclination, and “urge” to refer to the immediate activation of a neural circuit.
The opposite of “want” is “dread.” Some activities or situations trigger an inhibitory or avoidant response. They weaken the neural circuits that caused us to do them in the first place or trigger a circuit that gets us out of the situation. And humans decided to call these activities and situations “bad” or “painful.” We defined our feeling towards them as “dread.”
Lobsters do feel pain
People boil lobsters alive for food. Some say this is morally acceptable. They argue that lobsters do not have advanced neurological systems, so they cannot feel pain. But lobsters do exhibit avoidant behaviors towards being boiled—they cling onto the edge of the pot, trying to escape. But avoidant behavior and “pain” are two sides of the same coin. So, yes, lobster do experience “pain”.
Pleasure is addictive
An activity is addictive if it increases our tendency to do it again. Hence, pleasure is addictive, by definition. You cannot find an activity that produces pleasure but does not increase your tendency to perform it.
Pleasure is learning
We learn by updating our neural circuits. So, reinforcing our neural circuits or inhibiting them are both forms of learning. Pleasure and pain are how we learn—similar to a reinforcement learning AI agent.
You can mess with your desire system
Have you asked yourself “what do I really want in life”? “What are my base desires?” Have you heard the verbose life advice to “discover your true passions”?
To a certain degree, they are all misguided. What you desire the most and what you are passionate about are not fixed facts written into your genetic code. It’s not something you discover through introspection or experience.
What you desire and what you want are mutable. They can be created and changed by what you do. Desire is addiction. You can induce yourself to be addicted to different activities. If an activity produces any pleasure chemical at all, you can repeat doing it. This activates the desire reinforcement feedback loop, increasing your tendency to perform it—until this activity becomes your new “passion.”
Passion can be cultivated. And how frequently you pursue pleasurable behavior X governs how passionate you are about X (or how strong your neural circuit for X is).
I wanted to write mote. I wanted to define more terms like “freedom,” “happiness,” “longing,” “sadness,” “depression,” and “purposefulness.” But then I realized there was too much speculations involved. Which is not really fair because philosophers were able to make up batshit crazy theories of how to the world works and get away with them… So, as an exercise to the reader, you can try to define these higher-up concepts using the definition of “pleasure.”