If we assume that physcialism is true and all that there is, then we can safely assume that what we think of as subjective experience and consciousness, is driven by the atoms in our brain and the particular arrangement of those atoms. But then we can reason that another person has a different set of atoms and a different arrangement of those atoms in his brain that forms a different "subjective experience"- since I know not what it's like to be another person but I know all there is to be me, I am assuming it's down to the different and distinct atoms of their brain and their particular arrangement. And so we can ask ourselves just how many atoms in the brain are responsible for subjective experience and how many we can safely get rid of/ replacing before we have a different subjective experience.

And the fact that:

  1. Radioactive decay and the changing of neurons means the exact set of atoms and arrangement of those atoms which formed my brain when I first had what I would call "consciousness" are probably not 100% same

  2. Those initial atoms and current atoms in my brain, had such a remote likelihood of forming my brain (of all the atoms in the universe)

Therefore, can one conclude that it's far more likely that what we would denote as subjective experience isn't necessarily tied to the atoms in our brain or their arrangement (otherwise for example, for all I know I didn't exist 10 years ago, and I just believe so because I have memories from 10 years ago), meaning it's more likely that there is some other explanation alongside physicalism, or that physicalism also implies "open individualism" (based on my above arguments)?

  • I assume a similar argument has been given before. Would be happy to look into any potential directions.
    – 83457
    May 17, 2019 at 15:00
  • I don't know how similar this is, but there are creationists that argue against abiogenesis and evolution based on the improbability of the chemistry. Also your point #2 is kind of confusing because memories and experience are formed dynamically in the brain. For example the chance of you being where you are now wearing what you're wearing now is astronomically unlikely based on where you were born, but is much more reasonable if say it was compared to where you were a millisecond ago.
    – Cell
    May 17, 2019 at 16:25
  • 1
    Any argument that argues for impossibility based on improbability is moot. The probability that all your ancestors met in the proper sequence , seduced each other, had sex before dying and that the male gamete carrying their DNA won the race among millions is infinitesimal. Yet, here you are.
    – armand
    May 17, 2019 at 22:13

2 Answers 2


If we do, as I assume you do, have subjective experiences then whether they are astronomically unlikely or not, they occur, whatever the truth or otherwise of physicalism. Astronomical unlikelihood is no more relevant in this case than the astronomical unlikelihood of human life emerging or occurring in our galaxy. Both subjective experiences and human life are real.

Extreme degree of improbability would be of relevance if we did not know that something emerges or occurs and we calculating the chances of its doing so.

We might, of course, as a mathematical exercise try to calculate the probability of subjective experiences, given physicalism, but the number of variables involved in making the calculation would itself be of astronomical magnitude and the probability widely open to error - error the extent of which we could not practically ascertain.

For the record, I incline to the dual aspect theory on which one and the same thing is physical and subjectively experiential, like two sides of a coin. You might press me on the probability of one and the same thing's having this dual aspect. I can only say that I suppose it to be so and have not considered its probability.

Nice question.


As a sort of side-note: I think that there is an important distinction between the emergence of a property (such as subjective experience) due to an exact physical arrangement, compared to an approximate physical arrangement. So even if ‘your brain’ creates ‘your subjective experience’, it seems quite reasonable to assume that ‘a brain’ would create ‘a subjective experience’.

Likewise, if your brain changes atomic configuration slightly, we should expect that you will continue to have a subjective experience, so long as your brain continues to resemble what we would consider to be ‘a brain’. If your brain took on the atomic configuration of a bunch of rocks, then we’d expect.. well... a drastic change in your subjective experience, to say the least. Arguing the position of ”the only experience I am sure exists is the one I am experiencing right now just sounds like a solipsistic exercise in considering the fleeting-ness of what we perceive to be ”now”.

And so we can ask ourselves just how many atoms in the brain are responsible for subjective experience and how many we can safely get rid of/ replacing before we have a different subjective experience.

It is well understood that the atomic makeup of your brain will be slightly different tomorrow than it is today. Further, your subjective experience is borne of more than just the arrangement of your brain cells, it would also involve your body, and it’s situation in the world. So this part of your question seems to be more about the persistence of what we would call ‘an individual’ through time. I do not see any way in which a changing subjective experience is an argument against physicalism in and of itself.

To answer your question more directly: even if it is improbable that humans with brains have come to be, the fact that we observe humans with brains does not necessarily imply some extra-physical phenomena at play. Improbable events do occur, after all, especially given enough time and opportunity. A 1-in-1-trillion chance is pretty good, given 1000 trillion trials. With this in mind, who’s to say that the emergence of beings with subjective experience is extremely improbable? Maybe the physical processes at play actually make it likely, given enough time and space.

Either way, we cannot be sure of the probability of humans with brains existing, and further, we as humans seem ill equipped to reason about probabilities within such unfathomably large bounds anyways. So using these probabilities to argue for or against physicalism seems difficult, given the uncertainties involved.

So the question is: are humans ‘lucky’ to exist at all? Maybe, but in any case, here we are, experiencing the world.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .