我在【研究學問的盲點與歧路】一欄中轉貼了Roy F. Baumeister教授的大作 -- Do You Really Have Free Will? (Baumeister 2013)；我也發表了一篇短評 -- 《淺談「自由意志」》(胡卜凱 2013)。最近讀到幾篇相關的文章(請見本欄以下貼文)，讓我有機會重新思考這個議題；導致我認為需要對我以前的看法做些釐清和修正。我將從以下幾個層面或角度討論這個議題。
「意」者，指「意念」、「意想」、「意願」、「意圖」、... 等等；「志」者，指實現或試圖實現這些「意念」、「意想」、「意願」、「意圖」、... 等等的「努力」、「堅持度」、「忍耐度」、... 等等。後者表現在一個人的「行動」。
有學者區分「意志的自由」和「行動的自由」(O’Connor 2010)。網路上討論「自由意志」的文章很多(New World Encyclopedia)。有興趣進一步了解這個議題的人可前往參考。
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一般討論這個議題的學者，往往把「責任」分成「道德責任」和「法律責任」來論述。由於我們當下身處於「後真相」( = 「真相不值兩個大洋」)時代，侈言「道德責任」有點矯作或不合時宜。我也大致接受尼采對「道德」所做的分析，我就只談「法律責任」
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老鼠有「自由意志」嗎？ - Neuroskeptic
Do Rats Have Free Will?
Neuroskeptic, the Discover, 11/12/14
New research on the neural basis of ‘spontaneous’ actions in rats could shed light on the philosophical mystery that is human ‘free will’.
The study, just published in Nature Neuroscience, is called Neural antecedents of self-initiated actions in secondary motor cortex. It’s from researchers Masayoshi Murakami and colleagues of Portugal’s excellently-named Champalimaud Centre for the Unknown.
The senior author is Zach Mainen, whom I interviewed recently after he helped organize the campaign for reform of Europe’s Human Brain Project.
Murakami et al. trained rats to perform a task requiring patience. In each trial, the rat heard a sound and had to wait in place until a second sound occured. If they waited, they got a large amount of water as a reward. If they moved to get some water too soon, however, they only got a small amount.
Using tiny electrodes implanted in the premotor cortex of the rats’ brains, Murakami et al. discovered that some neurons seemed to act as “integrators” (or counters) – over the course of the waiting period, their firing activity gradually increased. If activity reached a certain threshold before the second sound played, the rat would stop waiting and ‘spontaneously’ decide to go for the small reward.
These “integrator” neurons didn’t always count at the same speed, however. On some trials, they ‘ramped up’ more quickly – and when this happened, the rat was more impatient. This image shows the relationship between ramp up rates and waiting time. (請至原網頁參考相關圖片)
Why did the integrators sometimes count faster than other times? Murakami et al. found a second class of neurons, whose rate of firing (which varied seemingly at random) predicted the rate at which the integrators “counted up”. The authors suggest, therefore, that these latter neurons provide inputs to the neural integrators. When the total amount of input reaches a threshold, a ‘spontaneous’ action is triggered.
What does this have to do with free will? Well, it all goes back to 1983, when a neuroscientist called Benjamin Libet found, using EEG, that a certain pattern of brain activity – a “readiness potential” – occurs in the human brain just before ‘spontaneous’ actions. In fact, this brain event happens even before we are aware of deciding to act.
Libet’s much-discussed finding has been seen as evidence against free will because it seems to suggest that ‘the brain decides to act before we do’.
But what if the readiness potential is somehow the equivalent of the rat “integrator”? That would be a big deal, say Murakami et al. In this case,
activity preceding bound crossing, either input or accumulated activity, could be said to participate causally in the timing of an action, but does not uniquely specify it. The integration-to-bound theory implies that no decision has been made until the bound has been reached… as at any moment up to bound crossing, the arrival of opposing inputs may avert an action.
In other words, maybe the readiness potential is not a consequence of a decision that has already been made, but rather is a contributor to a decision that only happens later.
This is in fact not a new idea. I blogged about this kind of interpretation of the Libet experiment last year, and integrate-to-bound models are quite common in neuroscience (e.g.). However Murakami et al. say that they’re the first researchers to find direct evidence for this model in decision making.
They conclude that the integrator threshold might even reflect the boundary between unconscious and conscious neural processes:
Crossing the threshold from unawareness to awareness [could be] a reflection of bound crossing [in the integrator].
In this way, the integration-to-bound theory may help to resolve the contradiction between the subjective report of free will and the requirement for causal antecedents to non-capricious, willed actions.
…our results provide a starting point for investigating mechanisms underlying concepts such as self, will and intention to act, which might be conserved among mammalian species.
Murakami M, Vicente MI, Costa GM, & Mainen ZF (2014). Neural antecedents of self-initiated actions in secondary motor cortex. Nature neuroscience, 17 (11), 1574-82 PMID: 25262496
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大腦神經學與自由意志相關嗎? - C. Jarrett
Belief in Free Will Not Threatened by Neuroscience
Christian Jarrett, 09/29/14
A key finding from neuroscience research over the last few decades is that non-conscious preparatory brain activity appears to precede the subjective feeling of making a decision. Some neuroscientists, like Sam Harris, have argued that this shows our sense of free will is an illusion, and that lay people would realize this too if they were given a vivid demonstration of the implications of the science (see below). Books have even started to appear with titles like My Brain Made Me Do It: The Rise of Neuroscience and the Threat to Moral Responsibility by Eliezer J. Sternberg.
However, in a new paper, a team led by Eddy Nahmias counter such claims. They believe that Harris and others (who they dub “willusionists”) make several unfounded assumptions about the basis of most people’s sense of free will. Using a series of vivid hypothetical scenarios based on Harris’ own writings, Nahmias and his colleagues tested whether people’s belief in free will really is challenged by “neuroprediction” – the idea of neuroscientists using brain activity to predict a person’s choices – and by the related notion that mental activity is no more than brain activity.
The research involved hundreds of undergrads at Georgia State University in Atlanta. They were told about a piece of wearable brain imaging technology – a cap – available in the future that would allow neuroscientists to predict a person’s decisions before they made them. They also read a story about a woman named Jill who wore the cap for a month, and how scientists predicted her every choice, including her votes in elections.
Most of the students (80 per cent) agreed that this future technology was plausible, but they didn’t think it undermined Jill’s free will. Most of them only felt her free will was threatened if they were told that the neuroscientists manipulated Jill’s brain activity to alter her decisions. Similar results were found in a follow-up study in which the scenario descriptions made clear that “all human mental activity just is brain activity”, and in another that swapped the power of brain imaging technology for the mind reading skills of a psychic. In each case, students only felt that free will was threatened if Jill’s decisions were manipulated, not if they were merely predicted via her brain activity or via her mind and soul (by the psychic).
Nahmias and their team said their results showed that most people have a “theory-lite” view of free will – they aren’t bothered by claims about mental activity being reduced to neural activity, nor by the idea that such activity precedes conscious decision-making and is readable by scientists. “Most people recognise that just because ‘my brain made me do it,’ that does not mean that I didn’t do it of my own free will,” the researchers said.
As neuroscience evidence increasingly enters the courtroom, these new findings have important implications for understanding how such evidence might influence legal verdicts about culpability. An obvious limitation of the research is its dependence on students in Atlanta. It will be interesting to see if the same findings apply in other cultures.
This post first appeared on the British Psychological Society’s Research Digest blog.
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「自由意志」的信念難以動搖 – D. Jones
A belief in free will is a tough one to shake
Dan Jones, 09/24/14
MOST people believe we have free will and so are the conscious authors of our own life stories. But if it were possible to use brain scans to predict our every action – showing that our choices are determined before we actually make them – would people abandon this belief in droves? Such knowledge would not by itself shake our confidence in our own volition, a new study suggests.
Many neuroscientists have argued that our sense of free will is nothing more than a by-product of the workings of a vast assembly of nerve cells. This is tied to determinism; the idea that every effect is connected by physical laws to a cause. This is why the behaviour of a physical system can be predicted – even the brain, in principle.
For some, such as author Sam Harris, what we know about neuroscience is incompatible with free will. As he puts it: "If determinism is true, the future is set – and this includes all our future states of mind and our subsequent behaviour."
If everyone lost their belief in free will, it could affect how we behave. People who are led to reject free will are more likely to cheat at things, for example, and are also less concerned about punishing other wrongdoers.
Those who see neuroscience and free will as incompatible argue that demonstrating the predictability of our brain should reveal the illusory nature of free will, and lead people to reject it. Experimental philosopher Eddy Nahmias at Georgia State University in Atlanta recently set out to test this idea.
Nahmias and his team told 278 participants a story of a future neuroimaging technology that allows perfect prediction of decisions based on a person's brain activity, recorded by a special skull cap. In this future world, a woman called Jill is fitted with a skull cap that allows scientists to predict everything she'll do with 100 per cent accuracy, including how she'll vote in upcoming elections. Contrary to expectations, 92 per cent of participants said that Jill's voting decision was of her own free will.
In another version of story, the scientists didn't just predict which way Jill would vote – they also manipulated her choice via the skull cap. In that scenario, most participants said that Jill did not vote of her own free will.
It was easy for people to see that being manipulated negated Jill's free will, but even when her behaviour was totally predictable, people still thought she acted on her own conscious reasoning, and so was responsible for her actions (Cognition, doi.org/vvc).
"People don't have detailed metaphysical views about what underlies free will," says Nahmias. What people believe is that their own conscious reasoning makes a difference to their behaviour – and nothing in neuroscience suggests it doesn't, he says.
"This paper breaks new ground," says Joshua Knobe, a philosopher at Yale University. "It suggests that whatever it is that we find threatening to free will, it isn't neuroscience."
This article appeared in print under the headline "A belief in free will is a tough one to shake"
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自由意志是個錯覺? - M. Burkley
Is Free Will a Magic Trick?
Melissa Burkley, 12/20/13
Watching Apollo Robbins' TED talk is highly entertaining, but it also gives us important glimpses into the nature of the human mind. Apollo is a skilled artist, not because he can steal a watch from under someone's nose but because he is able to direct the attention of his "victim" (and the audience) to exactly where he wants it. Watching his elegant dance of behavior manipulation made me question how much control we really have over our own behavior.
When it comes to this question, most people believe in the human capacity for free will. You are who you are because you chose to be. But as a social psychologist I spend most of my time focusing on the power of the situation. The environment you were raised in and the people that surrounded you had a big impact on the person you are now, in goods ways and bad. Within the last two decades, social psychologists have identified a number of ways that external pressures unconsciously nudge us to make certain choices; much like Apollo nudges his victim. I can make you like someone just by heating up the temperature of a cup of coffee you are holding. I can make you find someone sexually attractive just by adding the color red to their wardrobe. I can make you more likely to cheat just by dimming the lights. As much as we don't like to admit it, we are constantly being pushed by others and our surroundings to behave in ways we otherwise would not.
In light of these findings, many psychologists argue free will is just a magic trick or illusion. In fact, there is evidence that milliseconds before you consciously decide to move your finger, the motor area of the brain becomes active. This suggests that your automatic brain (or what Apollo called "Frank") decided to move your finger and then tricked you into thinking it was your idea. Now personally, I don't believe that all free will is an illusion. I think we all have free will, but we don't have as much as we think. External forces whittle down our choices in unconscious ways; tricking us into thinking we have more free will than we really do. At any point in time you could direct your attention away from where Apollo wants you to look (focus on the hand) and instead look at what his other hand is doing (slipping off his tie), but most of us don't. So although we feel like we have an infinite number of response choices, the Apollo-like "attention managers" in our lives have narrowed our field of vision to just a few.
Nowhere is this narrowing of options more evident than the "pick a card" trick magicians often perform. The magician waives a deck of cards in front of your face and asks you to mentally select any card from the deck. Moments later, the card you picked is in some bizarre location (sticking to ceiling, folded in the magician's wallet). Most of us figure out the card was in that location all along. But what we can't wrap our head around is how the magician knew what card we were going to pick before we picked it! Our sense of free will tells us we could have picked any of the 52 different cards, so the odds the magician would guess right are astronomical, right? But what if they could manipulate our free will so that we "freely choose" the card they wanted us to? Then this trick isn't that difficult. The way this often works is that the magician primes you with the desired card choice just before you make your pick. So the magician may flip through the deck quickly while you are making your choice, stopping ever so slightly on a particular card (e.g., 5 of hearts). Your conscious mind doesn't pick up on it, but your unconscious mind (your Frank) does. Suddenly the 5 of hearts is at the forefront of your mind. So when it comes time to pick a card, you think you selected it out of thin air, but you really picked it from the only card choice currently available in your mind. This is not to say that doing this trick is easy. Magicians spend thousands of hours perfecting their manipulations. And so too do the other pushers in our lives: the advertisers, politicians, media, even our loved ones. We all nudge each other in subtle ways to get what we want.
But what if you don't want to be nudged? Like most things in life, the first step is recognizing the problem. Whenever you feel like your options are limited -- like you just have to buy that new tech gadget or you have to do what your friend is requesting -- stop and take a step back. You probably feel this way because someone or something has narrowed your view to just one choice. But there are usually more options available than we think. Recognizing those moments when we feel our choices are limited truly frees up our free will.
Ideas are not set in stone. When exposed to thoughtful people, they morph and adapt into their most potent form. TEDWeekends will highlight some of today's most intriguing ideas and allow them to develop in real time through your voice! Tweet #TEDWeekends to share your perspective or email tedweekends@hufﬁngtonpost.com to learn about future weekend's ideas to contribute as a writer.
意志有其原因並不”自由” - J. A. Bargh
The Will Is Caused, Not "Free"
Our belief in free will is mainly self-serving.
John A. Bargh, Ph.D., Psychology Today, 06/23/09
Note: The following is a summary of our side of a recent debate with Roy Baumeister on free will, held at the annual convention of the Society of Personality and Social Psychology last February in Tampa, Florida. It appears in the current issue of Dialogue, the SPSP newsletter, along with a companion piece by Roy and Kathleen Vohs on determinism and causality. My co-author is Brian Earp, erstwhile ACME lab manager.
We welcome the opportunity to summarize our main points from the SPSP debate; first though we will respond to the additional arguments by Baumeister and Vohs in this issue concerning determinism and causality. We see no problem with the assertions that psychologists need not be strict determinists to practice their science, and that determinism and causality are not the same thing. However, neither of these points is relevant to the basic question of free will. The ‘free' in free will means freedom from causation, either by external forces (in the political sense of the term) or internal ones (in the psychological sense); and in our view it is just as problematic to claim that the will is uncaused as it is to argue it is not determined.
Free will may be defined as an agent's ability to act on the world by its own volition, independently of purely physical (as opposed to metaphysical) causes and prior states of the world. The folk notion of free will is laden with the concept of a soul, a non-physical, unfettered, internal source of choice-making-in other words, an uncaused causer. "The soul" may have gone out of fashion, and "the mind" taken over many of its functions and connotations, but the intuitive notion of free will has stayed much the same: there is something inside each of us that allows us to make "real" choices -- choices that even an omnipotent being, one who knew every environmental influence, and every physical fact leading up to the choice-making event, could not foretell with perfect confidence and accuracy. Determinism, if it were true, would indeed rule out this sort of free will, or shunt it into the realm of total redundancy. But indeterminism (of whatever flavor) isn't any kinder to the notion. Just because some event is not strictly determined by prior physical data doesn't mean it is caused by a free will. It may be simply indeterminately, probabilistically, or (to whatever degree) "randomly" caused by prior physical data. (If one wishes nonetheless to use the existence of error variance as evidence for the existence of free will, we can only point out that our business as scientists is to strive to reduce this unexplained variance by replacing it with explanation. Calling it ‘free will' and walking away satisfied rather misses the point.)
But let us assume that there is a free, internal source of control that guides our behavior and is ultimately responsible for ‘real' choices. To attribute human behavior to this mystical source is to place one's bets on an increasingly shrinking sphere. The project of social psychology, after all, has been to identify
(a) external-to-the-individual causes of judgment, motivation, and behavior, such as situational influences, and
(b) internal-to-the-individual causes, which research has shown increasingly to operate outside of awareness and conscious intention-not "freely chosen" in any sense of the term.
Are there some human behaviors that are possible only if free will exists and is a true causal source of action? There may be. But let's not give up on the search for non-mystical causes just yet.
This brings us to an area of agreement revealed in the debate:
that a belief in free will is important for human strivings.
People cherish their sense of control over the world and their own behavior. In the debate, we noted recent empirical articles by Vohs and by Baumeister showing negative consequences (cheating, aggression) of informing participants that free will does not exist. Our response to these ‘new' articles is that our field revealed the existence of such positive illusions decades ago, and we already know how essential they are to normal functioning. Clearly it is motivating for each of us to believe we are better than average, that bad things happen to other people, not ourselves, and that we have free-agentic control over our own judgments and behavior -- just as it is comforting to believe in a benevolent God and justice for all in an afterlife. But the benefits of believing in free will are irrelevant to the actual existence of free will. A positive illusion, no matter how functional and comforting, is still an illusion.
And we must caution against drawing conclusions from such research findings (implicitly or explicitly) that we should either
(a) not make findings against the existence of free will known to the public or
(b) stop doing such research altogether.
The belief in personal free will is a deeply rooted aspect of human phenomenal experience, and is so powerful that even those who do not subscribe to it intellectually still feel it in their personal lives as much as everyone else. It is not uncommon for one's first-person experience to be at odds with physical reality: 500 years after Copernicus we still see a morning sunrise, not the earth (and ourselves) tilting towards the sun, even though we know better scientifically. As Dan Wegner, Paul Bloom, Dan Dennett, and others have argued, there are strong natural supports for the belief in supernatural entities, just as there are for free will -- and sunrises too, for that matter. And if, as countless recent surveys show, the prodigious evidence in favor of evolutionary theory accumulated over the past 150 years has done little to erode the popular belief in a creator-god, then we can rest assured that the relatively nascent research on unconscious causes of motivation, judgment, and behavior will not result in anarchy or the collapse of social norms and moral behavior.
We should also not forget past social psychological research demonstrating that the belief in personal free will is selective:
people routinely make self-serving attributions about the causes of their behavior.
We take credit for the positive things we do (free will), but not for our misdeeds and failures ( "I had no choice", "I was abused as a child", "I was angry"). This suggests to us that much of the emotion surrounding the issue of free will is not about freedom per se but about self-esteem maintenance. We take personal pride in our ancestors, our blue eyes or rich brown skin, our height or birthday or name (as in the name-letter effect) -- none of which we chose or had any control over. Accordingly, we analyzed hundreds of individuals' spontaneous self-descriptions, and indeed 34% of their first-to-mind completions to the stem "I am _____" were such non-chosen aspects of self. It seems that people do not possess a consistent belief in free will so much as they strongly wish to take credit for the good things they are and do (regardless of whether they caused them), and to distance themselves from the bad things (even if they caused them). Evidently, the belief in free will is not principled, but socially strategic in nature.
So what, then, if one's will is not ‘free' of internal causation? It is still your will and my will and each is unique: a confluence of genetic heritage, early absorption of local cultural norms and values, and particular individual life experiences. After all, one can claim personal ownership of one's will just as much as one claims ownership of one's name, eye color, and birthday, and be as proud of one's will and its products as one is proud of the exploits of great-great-Grandma the pioneer, even though one's ‘free will' played no role in any of these.
John Bargh and ACME Lab at Yale University conduct research on the unconscious causes of our preferences, motivations, and social behavior. ACME publications are freely available at www.yale.edu/acmelab
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In light of these findings, many psychologists argue free will is just a magic trick or illusion. In fact, there is evidence that milliseconds before you consciously decide to move your finger, the motor area of the brain becomes active. This suggests that your automatic brain (or what Apollo called "Frank") decided to move your finger and then tricked you into thinking it was your idea (Burkley 2013).
This suggests that your automatic brain (or what Apollo called "Frank") decided to move your finger and then tricked you into thinking it was your idea.
* Bargh, J. A. 2009, The Will Is Caused, Not "Free", http://www.psychologytoday.com/blog/the-natural-unconscious/200906/the-will-is-caused-not-free
* Baumeister, R. F. 2013, Do You Really Have Free Will? http://www.slate.com/articles/health_and_science/science/2013/09/free_will_debate_what_does_free_will_mean_and_how_did_it_evolve.single.html
* Burkley, M. 2013, Is Free Will a Magic Trick?, http://www.huffingtonpost.com/melissa-burkley-phd/is-free-will-a-magic-tric_b_4467625.html?utm_hp_ref=science&ir=Science，請見本欄貼文《自由意志是個錯覺?》。
* Clark, T. M. 2009, Fully Caused: Coming to Terms with Determinism, http://www.naturalism.org/determinism.htm
* New World Encyclopedia, Free Will, http://www.newworldencyclopedia.org/entry/Free_Will
* O’Connor, T. 2010, Free Will, http://plato.stanford.edu/entries/freewill/
* 胡卜凱 2013，《淺談「自由意志」》，http://city.udn.com/2976/5014522?tpno=0&cate_no=52524
* 胡卜凱 2003，《「應無所住而生其心」討論 3》，http://www.rossety.com/fokas/article.php?op=articletext&id=199&db=0&PHPSESSID=735d85784d66b2bec3bff9cdeff82794
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