You don't have free will, but don't worry.

today i want to talk about an issue that must have occurred to everyone who spent some time thinking about physics which is that the idea of free will is both incompatible with the laws of nature and entirely meaningless i know that a lot of people just do not want to believe this but i think you are here to hear what the science says so i will tell you what the science says in this video i first explain why free will does not exist indeed makes no sense and then tell you why there are better things to worry about i want to say ahead that there is much discussion about free will in neurology where the question is whether we subconsciously make decisions before we become consciously aware of having made one i am not a neurologist so this is not what i'm concerned with here i will be talking about free will as the idea that in this present moment there are several futures which are possible and your free will plays a role for selecting which one of those possible futures becomes reality this i think is how most of us intuitively think of free will because it agrees with our experience of how the world seems to work it is not how some philosophers have defined free will and i will get to this later but first let me tell you what's wrong with this intuitive idea that we can somehow select among possible futures last week i explained what differential equations are and that all laws of nature which we currently know work with those differential equations these laws have the common property that if you have an initial condition at one moment in time for example the exact details of the particles in your brain and all your brain's inputs then you can calculate what happens at any other moment in time from those initial conditions this means in a nutshell that the whole story of the universe and every single detail was determined already at the big bang we're just watching it play out these deterministic laws of nature apply to you and your brain because you are made of particles and what happens with you is a consequence of what happens with those particles a lot of people seem to think this is a philosophical position they call it materialism or reductionism and think that giving it a name that ends on ism is an excuse to not believe it well of course you can insist to just not believe reductionism is correct but this is denying scientific evidence we do not guess we know that brains are made of particles and we do not guess we know that we can derive from the laws for the constituents what the whole object does if you make a claim to the contrary you are contradicting well-established science i can't prevent you from denying scientific evidence but i can tell you that this way you will never understand how the universe really works so the trouble with free will is that according to the laws of nature that we know describe humans on the fundamental level the future is determined by the present that the system in this case your brain might be partly chaotic does not make a difference for this conclusion because chaos is still deterministic chaos makes predictions difficult but the future still follows from the initial condition what about quantum mechanics in quantum mechanics some events are truly random and cannot be predicted does this mean that quantum mechanics is where you can find free will sorry but no this makes no sense these random events and quantum mechanics are not influenced by you regardless of exactly what you mean by you because they are not influenced by anything that's the whole point of saying they are fundamentally random nothing determines their outcome there's no will in this not yours and not anybody else's taken together we therefore have determinism with the occasional random quantum jump and no combination of these two types of laws allows for anything resembling this intuitive idea that we can somehow choose which possible future becomes real the reason this idea of free world turns out to be incompatible with the laws of nature is that it never made sense in the first place you see that thing you call free will should in some sense allow you to choose what you want but then it's either determined by what you want in which case it's not free or it's not determined in which case it's not a will now some have tried to define free will by the ability to have done otherwise but that's just empty words if you did one thing there's no evidence you could have done something else because well you didn't really there is always only your fantasy of having done otherwise in summary the idea that we have a free will which gives us the possibility to select among different futures is both incompatible with the laws of nature and logically incoherent i should add here that it's not like i'm saying something new look at the writing of any philosopher who understands physics and they will acknowledge this but some philosophers insist they want to have something they can call free will and have therefore tried to redefine it for example you may speak of free will if no one was in practice able to predict what you would do this is certainly presently the case that most human behavior is unpredictable though i can predict that some people who did not actually watch this video will leave a comment saying they had no other choice than leaving their comment and think they are terribly original so yeah if you want you can redefine free will to mean no one was able to predict your decision but of course your decision was still determined or random regardless of whether someone predicted it others have tried to argue that free will means some of your decisions are dominated by processes internal to your brain and not by external influences but of course your decision was still determined or random regardless of whether it was dominated by external or internal influences i find it silly to speak of free will in these cases i also find it unenlightening to have an argument about the use of words if you want to define free will in such a way that it is still consistent with the laws of nature that is fine by me though i will continue to complain that's just verbal acrobatics in any case regardless of how you want to define the word we still cannot select among several possible futures this idea makes absolutely no sense if you know anything about physics what is really going on if you are making a decision is that your brain is running a calculation and while it is doing that you do not know what the outcome of the calculation will be because if you did you wouldn't have to do the calculation so the impression of free will comes from our self-awareness that we think about what to do combined with our inability to predict the result of what we are thinking before we are done i feel like i must add here a word about the claim that human behavior is unpredictable because if someone told you that they predicted you'd do one thing you could decide to do something else this is the rubbish argument because it has nothing to do with human behavior it comes from interfering with the system you are making predictions for it is easy to see that this argument is nonsense because you can make the same claim about very simple computer codes suppose you have a computer that evaluates whether an equation has a real valued root the answer is yes or no you can predict the answer but now you can change the algorithm so that if you input the correct answer the code will output the exact opposite answer so yes if you predicted no and no if you predicted yes as a consequence your prediction will never be correct clearly this has nothing to do with free will but with the fact that the system you make a prediction for gets input which the prediction didn't account for there's nothing interesting going on in this argument another objection that i've heard is that i should not say free will does not exist because that would erode people's moral behavior the concern is you see that if people knew free will does not exist then they would think it does not matter what they do this is of course nonsense if you act in ways that harm other people then these other people will take steps to prevent that from happening again this has nothing to do with free will we are all just running software that is trying to optimize our well-being if you caused harm you are responsible not because you had free will but because you embody the problem and locking you up will solve it there have been a few research studies that supposedly showed a relation between priming participants to not believe in free will and them behaving immorally the problem with these studies if you look at how they were set up is that people were not primed to not believe in free will they were primed to think fatalistically in some cases for example they were being suggested that their genes determine their future which needless to say is only partly correct regardless of whether you believe in free will and some more nuanced recent studies have actually shown the opposite a 2017 study on free will and moral behavior concluded we observed that disbelief in free will had a positive impact on the morality of decisions towards others please check the information below the video for a reference so i hope i have convinced you that free will is nonsense and that the idea deserves going into the rubbish bin the reason this has not happened yet i think is that people find it difficult to think of themselves in any other way than making decisions drawing on this non-existent free will so what can you do you don't need to do anything just because free will is an illusion does not mean you're not allowed to use it as a thinking age if you lived a happy life so far using your imagined free will by all means please keep on doing so if it causes you cognitive dissonance to acknowledge your belief in something that doesn't exist i suggest that you think of your life as a story which has not yet been told you are equipped with a thinking apparatus that you use to collect information and act on what you have learned from this the result of that thinking is determined but you still have to do the thinking that's your task that's why you are here i am curious to see what will come out of your thinking and you should be curious about it too why am i telling you this because i think that people who do not understand that free will is an illusion underestimate how much their decisions are influenced by the information they are exposed to after watching this video i hope some of you will realize that to make the best of your thinking apparatus you need to understand how it works and pay more attention to cognitive biases and logical fallacies thanks for watching see you next week

Channel: Sabine Hossenfelder

Views: 1,243,936

Keywords: science, physics, philosophy, free will, determinism, do we have free will, does free will exist, is free will real

Id: zpU_e3jh_FY

Length: 11min 4sec (664 seconds)

Published: Sat Oct 10 2020