Response to Stimuli

Part of what it means to be a living organism is the ability to respond to stimuli. Something that is not alive, like a rock or a truck, cannot respond to things on its own. If a rock starts rolling there is nothing it can do to stop itself. If a truck starts rolling, it had better be because somebody wanted it to.

Living things can respond to stimuli. A plant can manipulate its internal pressure to face towards the sun. A mouse can run away from a cat. Even a microorganism can recoil if it gets too close to something it doesn’t like.

But responding to stimuli is not the same thing as free will. Even humans, with our gigantic brains, can’t always control how we react to things. In fact, we never really choose how to react. That is why it’s called a reaction.

Mushroom Cloud

Do you think those Hydrogen atoms chose to react this way?

You might think you are the master of your body, but when someone holds a flame close, you will jump away from the heat. If someone rubs pollen in your nose, you will probably sneeze. And it’s not just the environment that produces reactions. If someone waves or smiles at you, chances are you will respond in kind. When someone hurts you or puts you down, you might do the same thing back. You might respond in mean. Sometimes these reactions just jump out of us. Even if we don’t want them to.

Gas Mask

Just like gas.

We can’t always choose how we react to things. But free will means we can choose how we respond to ourselves. How do we react to our reactions? Sometimes I get scared and nervous. I can’t really help that. The world is a scary and nerve-wracking place. But after words, I don’t have to feel bad or ashamed. I can choose to tell myself that next time I will do better, rather than dwell on my failure.

Sometimes things make me sad, but I don’t have to let sadness overtake me. Sometimes things I can’t control make me angry, but I can control whether or not to think about those rage-inducing things later.

Living organisms respond to stimuli, but can’t always control these reactions. Intelligent creatures respond to themselves, and do not let the sum of their reactions define who they are.


That’s what dictionaries are for.