I've always learnt that life is nothing but a set of biological processes that emerge from various complex chemical reactions. Everything in biology can be expressed in terms of various chemical processes and reactions; there is nothing supernatural among living things.

Let's think about how we think. Our thoughts also must be just chemical reactions that are governed by various factors. Everything that I think is nothing but a complex set of chemical processes.

Does this mean that anything that I think is not in my control but in the control of the reactions that happen in my brain? Am I not free to think? Is it nothing that I think of my own will as all of it is only governed by seemingly random chemical reactions?

  • Light enters your eye, gets focused by the lens onto your retina, where it causes a biochemical reaction that's transmitted over the optic nerve to your visual cortex, and then you have a subjective experience of seeing. No cognitive scientist or neuroscientist in the world has the slightest clue how that last part happens. Perhaps you could ask the next person who tells you that "life is nothing but a set of biological processes," my emphasis. I'm curious to know what they say. Of course there's an extensive philosophical literature on the question, which is perhaps what you're seeking.
    – user4894
    Feb 27, 2022 at 6:21
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    If "life is nothing but a set of biological processes", then, a book is nothing but a set of letters. There's no point in discussing the argument of the book if you see it as a bunch of letters. Either you see it as a set, or either you see it as the system with emergent properties that it conforms. Thinking is not only a set of chemical reactions.
    – RodolfoAP
    Feb 27, 2022 at 9:03
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    Your materialistic explanation about philosophy of mind and free will can be classified as eliminative materialism: ...is the relatively new idea that certain classes of mental entities that common sense takes for granted, such as beliefs, desires, and the subjective sensation of pain, do not exist. The most common versions are eliminativism about propositional attitudes (Paul and Patricia Churchland)...about qualia, as expressed by Daniel Dennett and Georges Rey. These philosophers often appeal to an introspection illusion... Feb 28, 2022 at 5:58

6 Answers 6


Some would say so, see e.g. https://en.m.wikipedia.org/wiki/Epiphenomenalism

However the question can also be answered differently in physicalism using a compatibilist view https://en.m.wikipedia.org/wiki/Compatibilism

Compatibilism is the belief that free will and determinism are mutually compatible and that it is possible to believe in both without being logically inconsistent.

However the problem is not solved, and in philosophy there are many possibilities discussed. This is generally known as the mind-body problem, see https://en.m.wikipedia.org/wiki/Mind%E2%80%93body_problem

The mind–body problem is a debate concerning the relationship between thought and consciousness in the human mind, and the brain as part of the physical body.[...]

Whether and if so how the brain processes produce human mind processes is not understood. As such the answer cannot currently be answered with a simple yes/no, only that there are many different philosophical approaches trying to correlate activities in the brain with activities in the subjective mind.

According to a recent survey, a majority of philosophers in academia are monist, atheist, compatibilists. Meaning they don't believe in god, they believe that the mind likely emerges from physical processes, and that (a useful version of) free will is possible even if our universe or our minds were determined by physical laws. We can however assume that this survey does not extend to all of mankind, which is likely theist, dualist, incompatibilist.


Part 1: Do physical states cause mental states?

What you are describing is commonly referred to as a mechanistic view, most famously advocated for by Descartes. While he claimed that this view can explain what appears to be mental states in non-human animals, he did not think if it could account for human mental states:

Although his conception of animals treated them as reflex-driven machines, with no intellectual capacities, it is important to recognize that he took mechanistic explanation to be perfectly adequate for explaining sensation and perception — aspects of animal behavior that are nowadays often associated with consciousness. He drew the line only at rational thought and understanding.

He believed the mechanistic view could not explain two aspects of human intelligence:

The mechanistic explanation of behavior does not apply to human beings, according to Descartes, for two reasons. First, human beings are capable of complex and novel behavior... Second, human beings are capable of the kind of speech that expresses thoughts.

Most modern philosophers who defend the mechanistic view (such as Peter Harrison and Peter Carruthers) do so by saying that arguments for animal consciousness are flawed. This type of argument is not very strong since it can be (over-)simplified as 'Because no one has proved me wrong, I must be right'.

If we accept the hypothesis you describe, that the mental state of a human is merely the results of the physical state the human is in, we would have to both advocate for a more extreme mechanistic view than Descartes proposed and explain how a physical state can give rise to a mental state. I want to stress that a person can hold this position, but they would have an extremely hard time defending it.

If you wanted to defend it, I would suggest looking into the field of mental causation (described here and here). It is primarily concerned with how mental states can result in physical behavior, but it is a place to start if you want to do more research.

P.S. Even if mental states are completely deterministic, that does not imply that free will does not exist.

  • Can you explain your final claim further ("P.S. Even if mental states are completely deterministic, that does not imply that free will does not exist)? Feb 27, 2022 at 12:58
  • The position that determinism and free will are can not mutually exclusive is understandable called compatibilism. The most famous compatibilist is probably Hume. He solved the problem by proposing a different definition of free will than is typically used. He said that a person has free will if the action it takes is dependent on what action she wants to take. Even if that desire results from a deterministic process, the fact that her action was in line with her desire is sufficient to say she acted with free will.
    – E Tam
    Feb 27, 2022 at 13:30
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    Thanks. I thought so. This is important for the O.P., who might benefit from looking into the online Stanford Encyclopedia of Philosophy's entries on 'consciousness', 'free will', 'hard determinism' and 'compatibilism'. Feb 27, 2022 at 14:00
  • He said that a person has free will if the action it takes is dependent on what action she wants to take. Even if that desire results from a deterministic process, the fact that her action was in line with her desire is sufficient to say she acted with free will. If the desire is from a deterministic process and the action is always with respect to the desire, doesn't that mean that the action is also deterministic? Where is 'free will' here?
    – Silica19
    Feb 28, 2022 at 17:38
  • The action is deterministic. What Hume is saying is that an agent has free will when their action is depend on what the agent desires. To oversimplify, the agent is free of outside influences.
    – E Tam
    Mar 1, 2022 at 22:45

Does this mean that anything that I think is not in my control but in the control of the reactions that happen in my brain? Am I not free to think? Is it nothing that I think of my own will as all of it is only governed by seemingly random chemical reactions?

Much depends on what "I" is here.

If "I" is some kind of immaterial soul trapped inside your body, with no ability to somehow influence its matter and your thoughts are due to the mechanical action of your brain, then yes to all of these questions. You would be like a man stuck inside a giant Japanese robot but unable to work its controls. Few, if any people who believe in souls adopt this view, however. They, instead, believe that somehow immaterial souls are able to "work the controls" of the brain.

If however, if "I" here is your body and brain and all its functionality, then no. The neuronal mechanisms of your brain are just how you carry out your thoughts and actions.

  • Why isn't there a definitive answer for this? Why should it depend on what I think of the scenario? Shouldn't there be a 'yes/no' answer for such a question? Can't science answer this?
    – Silica19
    Mar 9, 2022 at 5:12
  • There may be a definitive answer, but I wrote the answer this way because since you didn't define what you meant by "I," I wanted to give a couple of possible meanings for what "I" might mean here. If you say that "I" should mean one and only one thing, you should look into the philosophical problems of identity: Ship of Theseus and the Sorites Paradox, for example. Or even just think about what exactly a "chair" is, a 100% definitive answer.
    – Chelonian
    Mar 10, 2022 at 16:57

The qualifier "just" in the title is misleading. The fact that a thermonuclear bomb is "just" physical reactions does not mean the construct "bomb" does not describe it anymore, or that the complex collection of "just elements" are not objectively powerful. We chose the containers for concepts—the words which we use to simplify concepts we observe.

Bringing that into your quandary: "anything that I think is not in my control but in the control of the reactions that happen in my brain?"

You draw two boxes, and ask us here to tell you which box your concept belongs in.

  • Box 1: "My control" (referring to the existential "I")
  • Box 2: "Complex chemical reactions in my brain" (The smallest observable components in your organ called the "brain")

But this bifurcation is a fallacy. Your brain is the existential you. The chemicals, and processes, and storage facilities are you. And so, even if the answer is "Box 2," the answer is Box 1.

Your meta question about supernatural forces does not enter into this calculation. No amount of progress toward knowing how a system works, as discovered by science, will ever allow us to understand why the system works. For example, we can observe neurons develop an electrical charge and reach a certain capacity, until it fires and draws an arc across an axion. A signal moves through the nerves which are now more conductive, and your thumb goes up. That is cool, and a neat trick. But why does it happen? What makes the electric charges? And the most paradoxical thing about it is: Why does it work so perfectly, so predictably, and so reliably no matter where you are in the universe?

You ask a question assuming that knowing how resolves questions of why, and this is illogical.


I feel that most of these questions aren't about “how do I think”, but rather “How can people, who exist with meaning, be made of pointless and meaningless atoms?”. This being the reason that people distinguish between ‘the mental state’ and ‘the physical state’. One is real, and the other gives life meaning. The body and the soul.

You don’t need to go through the gymnastics of “Justification for free will” or “Love is just a hormone”, or any existentialist stuff.

Just saying “Oh, so that gray piece is the part of me that feels love. Cool.” nullifies any argument that people don’t have free will, or lack meaningful existence. Chemicals and neurology then become part of what it means to have free will, rather than an obstacle to it. You’re a chemical reaction. Embrace it!

  • Do you mean a 'yes' to my question? Does free will truly doesn't exist?
    – Silica19
    Mar 9, 2022 at 5:14
  • It exists as much as you want it to! The history of philosophy is littered with people finding that they are physical objects, and creating loopholes to justify the idea that they’re aren’t. But there isn’t a loophole. There is no logical way to apply freedom onto carbon and glucose. Which is why you don’t justify free will, or the idea that people matter. Because it’s something you choose. It’s something that you create from nothing, in defiance of nature and god. You don’t justify your life, you choose to live it.
    – Dingle
    May 5, 2022 at 17:00

Thinking is mostly about understanding the circumstances, considering alternative future scenarios, evaluating them and coming up with plans on how to make the future more aligned with personal preferences.

None of this is possible for chemical reactions no matter how complex they might be. Thoughts are not physical events. Thoughts are information being processed.

  • What fundamentally goes on in our brains as we think? Some neurochemical processes/reactions, isn't it?
    – Silica19
    Feb 28, 2022 at 17:33
  • Neurochemical reactions and mental processes are completely different things, even though they both occur in the brain. Feb 28, 2022 at 17:43
  • What leads to mental processes?
    – Silica19
    Feb 28, 2022 at 18:37
  • Please do not answer with personal opinions, but rather with philosophical references, in particular when advertising views that are not philosophical consensus.
    – tkruse
    Mar 1, 2022 at 0:19
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    @Pertti Ruismäki “Thoughts are by definition something else than physical events” clearly thinking about a tree is not a tree, but according to what definition is a thought not a physical event, in the sense that it may manifest as a series of chemical changes.
    – Frog
    Mar 8, 2022 at 18:54

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