¿Existe el libre albedrío?

Es una tranquila tarde de domingo. El profesor Freeman está disfrutando del clima del sur de California en el patio del profesor Domino.

Domino: ¿Le gustaría una Coca-Cola o una Pepsi, Dr. Freeman?

Freeman: Esa es una elección fácil, Dr. Domino.

Domino: Ah, ¿lo es? Supongo que las neuronas de su cerebro ya han decidido por usted. ¿Acaso no hay mucha investigación neurocientífica que demuestre que los humanos carecen de libre albedrío?

Freeman: Sí, pero mucho de eso es basura.

Domino: ¿En serio? ¿Conoce el experimento clásico llevado a cabo por Benjamin Libet y sus colegas?

Un experimento audaz

Libet's clock Knowing Neurons
el reloj de Libet

Freeman: ¡Por supuesto! Libet y sus colegas diseñaron un experimento para probar si los sujetos humanos tenían libre albedrío. Se instruyó a los sujetos para que presionaran un botón cada vez que sintieran ganas de hacerlo. Un dial giratorio servía como reloj para que cada sujeto pudiera anotar la hora exacta en que se dio cuenta de su deseo por presionar el botón. Mientras cada individuo participaba en el experimento, <a class="glossaryLink" aria-describedby="tt" data-cmtooltip="

EEG
Electroencephalogram, a technique that places electrodes on the scalp to measure electrical brain activity.
" href="https://knowingneurons.com/glossary/eeg/" target="_blank" data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]">EEG electrodos de electroencefalografía adheridos al cuero cabelludo midieron actividad eléctrica en el cerebro que indicaba una preparación para el movimiento que precedía a la decisión consciente del sujeto de presionar el botón por más de un tercio de segundo.

Domino: Entonces, Dr. Freeman, ¿será que los resultados de este estudio muestran que los sujetos tenían la opción de escoger? ¿O más bien que las decisiones estaban predeterminadas por la actividad eléctrica del cerebro?

Freeman: Hay dos problemas con el experimento del Dr. Libet. Primero, como ha señalado el filósofo Alexander Batthyany, se les dijo a los sujetos que esperaran pasivamente el deseo de presionar el botón. Naturalmente, un impulso subconsciente podría manifestarse primero como actividad eléctrica cerebral antes de elevarse al nivel de la consciencia. En segundo lugar, como ha señalado el filósofo y científico cognitivo Daniel Dennett, hay un cambio en la atención de un estado interno a uno externo, cuando se pasa de sentir las ganas de presionar el botón a anotar la hora mostrada en el reloj. Debido a que lleva tiempo reasignar los recursos neuronales para este cambio de atención, la brecha de 350 milisegundos se puede explicar fácilmente.

LibetExperiment

Domino: ¡Gracias a Dios que tenemos filósofos velando por nosotros! Pero, ¿ha considerado el trabajo de John-Dylan Haynes y sus colegas? ¡Este grupo de investigadores demostró que la actividad cerebral metabólica medida con la resonancia magnética funcional puede predecir qué mano usará un sujeto para presionar un botón varios segundos antes de que se haga la elección! seconds before the choice is made!

Freeman: Pff... eso es una exageración. La precisión de la predicción de este estudio fue solo del 60%, apenas mejor que el azar.

Domino: Aún así, la mayoría de las veces, esta elección estaba predeterminada por la actividad cerebral del individuo hasta siete segundos antes de que él o ella tomaran la decisión.

Freeman: Está bien. En aras del argumento, supongamos que la precisión de la predicción hubiera sido del 100%. ¿Qué más estaría determinando las acciones del sujeto aparte de la actividad cerebral? ¡Yo realmente espero que sea mi cerebro el que esté tomando mis decisiones! ¿Y quién dice que las decisiones se toman instantáneamente? No me sorprende que una decisión pueda ocurrir en el transcurso de varios segundos. hope my brain is making my decisions! And who says that decisions are made instantaneously? It doesn’t surprise me that a decision could occur over the course of several seconds.

Domino: Ah, pero si creemos en el libre albedrío, creemos que nada fuera de nosotros determina nuestras decisiones. Y, sin embargo, la ciencia demuestra que nuestro cerebro es una máquina, sujeta a las leyes de la naturaleza como cualquier otra máquina. Nuestras neuronas obedecen las leyes de causa y efecto, el determinismo, mientras que tendrían que actuar desafiando esas leyes si realmente tuvieras voluntad propia.

Redefiniendo el libre albedrío

Freeman: Acaba de argumentar que los resultados de estos experimentos son irrelevantes ya que, según usted, el libre albedrío es imposible incluso al principio. Bien. Pero no estoy de acuerdo con que el libre albedrío sea incompatible con el determinismo. Para mí, el libre albedrío es simplemente la idea de que soy libre de hacer lo que quiero, sin importar si mis deseos están, a su vez, determinados por otra cosa.

Domino: Eso no me parece libre albedrío. Un robot programado para realizar incesantemente alguna tarea insignificante podría tener libre albedrío en ese sentido.

Freeman: Bueno, ninguna tarea es objetivamente insignificante. ¡Para un extraterrestre asexual de Marte, la tarea de copular con hermosas mujeres para producir descendencia podría parecer insignificante! Permítame citar al difunto escritor de ciencia ficción Philip K. Dick: «La realidad es aquello que cuando dejas de creer en ella, no desaparece». ¿Ha oído hablar alguna vez de la enfermedad de Huntington, Dr. Domino?

Domino: Sí, es una enfermedad terrible.

Freeman: Así es. La enfermedad de Huntington es un trastorno neurodegenerativo en el que las personas experimentan movimientos involuntarios similares a los de un baile. Y ya sea que crea o no en el libre albedrío, todavía tengo una especie de libre albedrío que una persona con la enfermedad de Huntington no tiene.

Domino: ¡Ah, pero un paciente con la enfermedad de Huntington sufre más que simples movimientos involuntarios! El paciente también puede experimentar cambios de personalidad, como hipersexualidad. Para ser verdaderamente libre, uno no solo debe tener control sobre sus movimientos corporales, sino también sobre sus deseos. Cuando consideramos casos como la enfermedad de Huntington o un tumor cerebral, generalmente reconocemos que el individuo no es responsable de estos cambios de personalidad. Y, sin embargo, casi todo el mundo experimenta cambios de personalidad similares durante la pubertad. No elegimos nuestras personalidades. La voluntad humana no es soberana e inmutable, sino que está controlada por la biología y la genética.

Freeman: Puede que tenga una personalidad ligeramente diferente a la que tenía cuando era niño, ¡pero no es como si la pubertad me quitara el libre albedrío!

Domino: Considere entonces al adicto que se siente obligado contra su voluntad a continuar abusando de las drogas hasta el punto de perder el trabajo, la familia, la dignidad y tal vez incluso la vida. ¿Este individuo tiene libre albedrío?

Freeman: Cada vez que el drogadicto tiene una recaída, él o ella elige satisfacer los deseos de consumo que son subjetivamente peores que las consecuencias de la recaída.

Domino: Eso no es lo que yo llamo libre albedrío.

La anatomía del control

Freeman: El filósofo Arthur Schopenhauer escribió una vez: «El hombre puede hacer lo que desea, pero no puede escoger lo que desea». La elección del adicto a las drogas de satisfacer un antojo es una elección libre, pero tiene poco control sobre los antojos.

Domino: Yes, little if any! The cravings are generated by the nucleus accumbens, part of the basal ganglia, a group of subcortical brain structures which have a largely unconscious yet profound influence on human behavior. The neurons of the nucleus accumbens release dopamina. which modulates attention and rewards certain behaviors. This dopaminergic modulation is the true motivation for many of our behaviors and can turn strong individuals into hopeless addicts.

Freeman: Ah, but the cerebral cortex—the neural substrate of the conscious self—has top-down projections which modulate the nucleus accumbens. If we equate the cortex with the self, the self can directly influence the activity of the nucleus accumbens and the rest of the brain, which in turn influences the self. For instance, we can change our brains through practices such as mindfulness and meditation to alleviate anxiety and intrusive thoughts. Neuroscientist Michael Gazzaniga has used similar arguments to assert that the self can alter the brain through top-down causation.

Dopamine_Knowing-Neurons

Pentomino_animation_1_minute_small
Cellular automata in John Conway’s Game of Life behave as if they have a will of their own, yet their behavior is completely predetermined.

Domino: Entiendo los argumentos de Gazzaniga. Sin embargo, si el universo es determinista, entonces mis acciones están predeterminadas y no hay lugar para el libre albedrío. Eche un vistazo a los autómatas celulares del juego Game of Life de John Conway. Game of Life. Estos seres realistas corren como si tuvieran voluntad propia, pero sus comportamientos están totalmente predeterminados por las condiciones iniciales de la cuadrícula en la que ocurre el juego.

Freeman: Yes, but cellular automata are just an abstract model.

Domino: But the same determinism applies to our universe! Consider a thought experiment conceived by the French mathematician Pierre-Simon Laplace: a demon knows the position and momentum of every particle in the universe. With this knowledge, the demon can predict the future of the entire universe according to Newtonian physics. Where is there room for choice in such a predetermined world?

Freeman: Yet today, we know that at the level of subatomic particles, nature behaves randomly. *

Domino: That’s true, but the ‘quantum indeterminacy’ you’re referring to doesn’t allow for free will either. If my choices are made by rolling dice, how does this make me free?

Freeman: Touché. I don’t deny that, at the level of biology, the universe is deterministic. If you define free will to mean freedom from determinism, then no, free will just doesn’t exist.

Domino: You admit defeat!

Free Will Worth Wanting

Freeman: Hold on a minute. Daniel Dennett, whom I mentioned earlier, makes the distinction between this sort of free will and the kind of free will “worth wanting.” In a lecture addressed to the Santa Fe Institute in 2014, he compares free will to magic. Real magic, in the sense of conjuring spells, is obviously fake, whereas fake magic, in the sense of slight of hand tricks, is real. Similarly, real free will is fake, and fake free will is real. The sort of free will worth wanting is the sort of free will you and I have which a Huntington’s disease patient lacks.

Domino: Hmm, this free will is still just an illusion. Your actions are still predetermined, you simply enjoy your predetermined behavior in a way that the Huntington’s disease patient does not. You still can’t will what you will, as Schopenhauer would say. Even with meditation and top-down mental causation, there are only so many levels to how far you can control your will. Say you want to change your feelings for someone. Your feelings for that person are a primary will, but perhaps you have a secondary will to change them. Your primary will shall change as a function of your secondary will. But what determines your secondary will, your desire to change these feelings? That will had to come from somewhere, right? So there must be a tertiary will determining your secondary will. But if you are completely free, that tertiary will must bow to a quaternary will … And so forth, ad infinitum. Free will is an incomplete concept!

Freeman: Yes, I have already conceded that that sort of free will is a logical impossibility. At any given moment, only one future is possible. That the brain decides according to some algorithm does no diminish my capacity to choose; on the contrary, this algorithm allows me to choose. How else could a decision be possible if not according to some computational procedure? We’ve already established that rolling dice is not a free choice. Now, say I’m given some choice in an experiment. If each trial is repeated exactly the same way, then in principle I should decide the same way each time. In practice, this is impossible, because after the first trial, I’d have the memory of the previous trials, which might influence my next decision. The fact that I can integrate previous decisions into my current decision and take a different path, this is all the free will “worth wanting,” as Dennett would say.

Rolling Dice
Events in our universe are either random, like the roll of dice, or predetermined, like the output of a computer program. Neither possibility seems to leave obvious room for human will. Nonetheless, rational arguments have been made that attempt to reconcile free will with these obstacles. The limits of human will become apparent in situations such as addiction, where the individual has difficulty controlling his or her actions.

What if you were Jack the Ripper?

Domino: But isn’t it your brain deciding for you? How is this a real choice?

Freeman: I am my brain, or at the very least my cerebral cortex. That’s the basis of monism, the idea that brain and mind are one substance. To say that the brain decided for me is to take a dualist approach based on the idea that the mind is some fundamentally different substance than the brain. Once I abandon the idea of dualism, the accusation of the brain deciding for me disappears.

Domino: But you didn’t choose your brain when you were born! And given that there are differences between the brains of sociopaths and normal individuals, how can you really say that you would’ve made different choices, had you been born as Jack the Ripper?

Freeman: That’s a meaningless question. To ask if I would have still murdered if I were Jack the Ripper is like asking if a car would fly if it were an airplane. Of course it would fly, it would no longer be a car! Would an electron be positively charged if it were a proton? I suppose so!

Domino: Although I strongly believe that free will does not exist … I suppose I see your argument.

Freeman: One more point. Researchers have shown that, after reading a passage from a book arguing against the existence of free will, subjects are more likely to subsequently cheat on a task they must perform to earn money than subjects who read a neutral passage. This work underscores the importance of believing in free will for exercising self-control. As Daniel Dennett has argued, telling people that neuroscience leaves no room for free will might not only be jumping to conclusions, but also irresponsible.

Domino: Interesting … Even though I think free will is an illusion, I’ll admit that it’s an important illusion.

Freeman: Finally, something we can agree on! Now, how abut that Pepsi?

Brain Chain

~

Footnote:

* Further objections to Laplace’s demon would include chaos theory and Heisenberg’s uncertainty principle. Chaos theory states that infinitely small changes in initial conditions may have very large effects. Heisenberg’s uncertainty principle states that infinitely precise measurement of both the position and momentum of a particle is impossible even in principle. Nonetheless, Domino’s argument that the macroscopic world is deterministic still holds.

~

Referencias 

Images from Information Philosopher, Wikimedia Commons (1, 2, 3, 4), and made by Jooyeun Lee.

Libet, Benjamin, et al. “Time of conscious intention to act in relation to onset of cerebral activity (readiness-potential).” Cerebro 106.3 (1983): 623-642.

Dennett, Daniel C. Freedom evolves. Penguin UK, 2004.

Batthyany, Alexander: Mental Causation and Free Will after Libet and Soon: Reclaiming Conscious Agency. In Batthyany und Avshalom Elitzur. Irreducibly Conscious. Selected Papers on Consciousness, Universitätsverlag Winter Heidelberg 2009, p.135ff.

Soon, Chun Siong, et al. “Unconscious determinants of free decisions in the human brain.” Nature neuroscience 11.5 (2008): 543-545.

Gazzaniga, Michael. Who’s in Charge?: Free Will and the Science of the Brain. Hachette UK, 2012.

Dennett, Daniel. “Is Free Will an Illusion? What Can Cognitive Science Tell Us?” Santa Fe Institute. James A. Little Theater, Santa Fe, NM. 14 May 2014. Lecture.

Vohs, Kathleen D., and Jonathan W. Schooler. “The value of believing in free will encouraging a belief in determinism increases cheating.” Psychological science 19.1 (2008): 49-54.

Joel Frohlich

Joel Frohlich es un investigador postdoctoral que estudia la consciencia en el laboratorio de Martin Monti en UCLA. Está interesado en utilizar la actividad cerebral registrada con el electroencefalograma para inferir cuándo es que una persona está consciente.  Joel obtuvo su doctorado en UCLA en el 2018 estudiando trastornos del neurodesarrollo por medio de la electroencefalografía en el laboratorio de Shafali Jeste. También puede consultar el blog de Joel, llamado «Consciousness, Self-Organization and Neuroscience on Psychology Today». Para obtener más información sobre la investigación y los ensayos de Joel, visite el sitio web de Joel en joelfrohlich.com.

Un comentario en «Does Free Will Exist?»

  • diciembre 10, 2017 en 2:39 pm
    Enlace permanente

    Free will is when we decide for ourselves what we “will” do, “free” of coercion or other undue influence. This is not a question of belief, but one of empirical fact. Whether someone is holding a gun to your head and forcing his will upon you, or whether you are free to make your own choice, is an empirical distinction.

    The concept of “freedom” is only meaningful when it references some meaningful and relevant constraint. For example, a bird may be set free (from its cage). A slave may be freed (from his master). We enjoy freedom of speech (free from political censorship). And, most of the time, we make choices of our own free will (free of coercion or undue influence).

    The paradox is not created by a misunderstanding of freedom, but by a misunderstanding of determinism. It arises from a reification fallacy, where the concept of “reliable causation” is treated as if it were a “thing”, some kind of natural force that acted upon physical objects. But no such thing exists.

    The physical universe is made up entirely of objects and the natural forces they exert upon each other. It is specifically the mass of the Sun and of the Earth, acting upon each other through gravity, that causes the Earth to fall in an elliptical orbit around the Sun. It is the properties internal to these two objects themselves that cause this orbit.

    “Causation” doesn’t cause anything. “Determinism” doesn’t cause anything. “Inevitability” doesn’t cause anything. Only the objects and forces themselves can actually be said to “cause” anything to happen.

    Hi there. It’s me. Unlike “causation”, I happen to be one of those objects that goes around causing stuff. But, unlike the Sun and the Earth, I cause stuff purposefully and deliberately. I am not just a physical object, but I am also a living organism and an intelligent species. As a living organism I an animated by a “biological will” to survive, thrive, and reproduce. That is integral to who and what I am. It is not anything external to me.

    I am also an intelligent species. This means that I have an evolved neurology capable of imagination, evaluation, and choosing. And this is the level of organization where “free will” emerges within the physical universe.

    The universe itself is an inanimate object. It has no purpose or will of its own. In fact, there is no purpose to be found anywhere in our universe except within living organisms and their species.

    Empirically speaking, if I am alone in a room with a bowl of apples, and I feel hungry, and I decide to eat one now, then the hunger is me, the choosing is me, the eating is me, and now the apple is also part of me. And when “that which is me” is identical to “that which is choosing” we call that “free will”.

    Oh, one very important thing. There is no such thing as “causal predeterminism”. An even can be predicted in advance, such that we can determine (know) that it will happen. But no event can be “already caused” until the last prior cause of the event has occurred.

    Hope that helps.

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