Sbagliando s'impera

Dennett, Daniel C. (2013). Intuition Pumps and Other Tools for Thinking. London: Allen Lane. 2013. ISBN 9780141970127. Pagine 458. 14,03 €

images-amazon.com

Ho incontrato Dan più di 30 anni fa, e da allora ci siamo sempre frequentati, anche se a volte ci siamo persi di vista per lunghi periodi. Me l’aveva presentato Doug Hofstadter, ma poi siamo diventati amici indipendentemente da lui …

Mi piacerebbe poterlo scrivere non soltanto metaforicamente, ma la realtà letterale è che – dopo avere letto Godel, Escher, Bach: An Eternal Golden Braid (non riesco a ricordare in quale anno, ma la mia copia è molto consunta ed è datata 1983) di Douglas R. Hofstadter, ed esserne rimasto folgorato (è certamente uno di quei libri che hanno contribuito più profondamente a cambiare il mio modo di pensare) – mi sono imbattuto in The Mind’s I: Fantasies and Reflections on Self and Soul, di cui Hofstadter era autore insieme a Daniel C. Dennett, all’epoca a me del tutto sconosciuto. Anzi, se devo essere sincero (sì, lo so che sono liberissimo di non esserlo, è soltanto un modo di dire), dall’alto della mia spocchia eurocentrica ero molto diffidente rispetto alla possibilità che potessero esistere dei filosofi americani. Per Hofstadter era stato amore a prima vista, cresciuto libro dopo libro (Metamagical Themas: Questing For The Essence Of Mind And Pattern del 1985, anche se io ho l’edizione Penguin del 1986; Fluid Concepts And Creative Analogies: Computer Models Of The Fundamental Mechanisms Of Thought del 1995) fino allo struggente Le Ton Beau De Marot: In Praise of the Music of Language del 1997. Paradossalmente, questo amore prima incondizionato ha mostrato qualche incrinatura proprio da quando ho avuto occasione di conoscere Doug Hofstadter personalmente nel 2004: ma forse quella di nutrire dubbi è una caratteristica dell’amore maturo. Resta il fatto che I Am a Strange Loop del 2007 mi è piaciuto meno degli altri libri (ne ho scritto una recensione su questo blog, che trovate qui).

Per Dennett le cose sono state molto diverse. A differenza di Hofstadter, Dennett non è un seduttore. Si concede con estrema riluttanza (sì, come il San Bernardo di cui scrive Snoopy).

linkiesta.it

Per anni, pur trovando interessanti i temi e le argomentazioni di Dennett, ho fatto molta fatica a leggerlo. Scriveva – se posso esprimermi così – da filosofo. Non pretendo mi crediate sulla parola. Facciamo così: riporto qui sotto l’inizio del primo capitolo di Brainstorms. Saggi filosofici sulla mente e la psicologia nella traduzione italiana edita da Adelphi, e voi giudicate da soli:

In questo capitolo esaminerò il concetto di un sistema il cui comportamento può, almeno occasionalmente, essere spiegato e previsto attribuendogli credenze e desideri (e speranze, paure, intenzioni, impressioni, ecc.). Chiamerò tali sistemi sistemi intenzionali, e tali spiegazioni e previsioni spiegazioni e previsioni intenzionali, in virtù dell’intenzionalità delle espressioni tipiche usate per designare le credenze e i desideri (e le speranze, le paure, le intenzioni, le impressioni, ecc.).
In passato, mi ostinavo a scrivere «intenzionale» con la I maiuscola ogni volta che intendevo usare la nozione di intenzionalità di Brentano, per distinguere questo termine tecnico da quello comune, per esempio, nell’espressione «una spinta intenzionale»; ma ora il termine tecnico è molto più usato, e poiché quasi tutti quelli che lo usano non sembrano preoccuparsi del rischio di confusione, ho deciso, con qualche trepidazione, di abbandonare questa eccentricità tipografica. Ma il lettore non iniziato si ritenga avvertito: «intenzionale» nel senso in cui appare qui non è il termine consueto della lingua ordinaria. Per me, come per molti autori contemporanei, l’intenzionalità è in primo luogo una caratteristica delle entità linguistiche – idiotismi, contesti – e per gli scopi che qui mi prefiggo basterà dire che un’espressione è intenzionale se la sostituzione di termini codesignativi non ne conserva la verità o se gli «oggetti» di queste espressioni non possono essere trattati nel modo usuale con i quantificatori. [pp. 37-38]

Si potrebbe usare questo testo in un corso di scrittura per illustrare come non si scrive un testo per non addetti ai lavori: frasi lunghe, vocaboli inconsueti introdotti senza spiegarli (che cosa diavolo sono i termini codesignativi?), gergo specifico della disciplina. E, soprattutto, il malcelato disprezzo per il lettore non iniziato che deve essere avvertito; disprezzo rivelatore della circostanza che il lettore ideale sarebbe invece il lettore iniziato.

Poi sono successe due cose che hanno del miracoloso. La prima è che, tutto d’un tratto, Dennett ha imparato a scrivere per un pubblico di non filosofi, per un pubblico cioè di persone di media cultura e con una bella voglia di imparare delle cose nuove: non dev’essere stato facile per lui e immagino abbia richiesto uno sforzo di volontà e l’acquisizione di tecniche e strumenti specifici. La seconda è che ha scritto anche lui un libro fondamentale, un altro di quei libri che hanno cambiato in modo permanente il mio modo di pensare: Consciousness Explained. Prima di leggerlo – durante le vacanze di natale del 1993-1994 a Roccamare, direi, dal momento che ho la seconda ristampa, 1993, dell’edizione Penguin, anche se il libro è del 1991 – ero pigramente convinto che quello della consciousness fosse un problema intrattabile, da lasciare alle elucubrazioni dei metafisici. Ricordo ancora l’emozione, la gioia, la sensazione di avere fatto una scoperta importante che quella lettura mi aveva lasciato. Ancora più delle argomentazioni di Dennett, che nel tempo si sono per lo più arricchite di significato e di elementi a sostegno, ma qualche volta si sono anche dimostrate sbagliate, è stato fare la scoperta, e raggiungere la convinzione, che non vi fosse nessun tema, nessuno, che non potesse e dovesse essere affrontato, e fruttuosamente, con i metodi e gli strumenti della scienza. Questa sensazione mi è rimasta dopo tutti questi anni, inseparabile da quelle vacanze di natale, dalle passeggiate in pineta con i miei figli (8 e 10 anni) e dagli esperimenti sulla tastiera (Bach, certamente; Wachet auf?).

 * * *

Quanto alle intuition pumps, penso di averle incontrate la prima volta – o, almeno, di essere stato per la prima volta consapevole del loro potenziale come strumento del pensiero – in un intervento di Daniel Dennett su Edge, il sito/blog (ante litteram) di John Brockman. Da allora le ho sempre usate nella mia prima lezione all’università, per cercare di stabilire un percorso intuitivo prima di procedere alle tradizionali (e pallose) spiegazioni deduttive, o come diavolo si chiamano. Ecco il testo che usavo:

If you look at the history of philosophy, you see that all the great and influential stuff has been technically full of holes but utterly memorable and vivid. They are what I call “intuition pumps” — lovely thought experiments. Like Plato’s cave, and Descartes’s evil demon, and Hobbes’ vision of the state of nature and the social contract, and even Kant’s
idea of the categorical imperative. I don’t know of any philosopher who thinks any one of those is a logically sound argument for anything. But they’re wonderful imagination grabbers, jungle gyms for the imagination. They structure the way you think about a problem. These are the real legacy of the history of philosophy. A lot of philosophers have
forgotten that, but I like to make intuition pumps.
[…]
I coined the term “intuition pump,” and its first use was derogatory. […] I went on to say that intuition pumps are fine if they’re used correctly, but they can also be misused. They’re not arguments, they’re stories. Instead of having a conclusion, they pump an intuition. They get you to say “Aha! Oh, I get it!”
The idea of consciousness as a virtual machine is a nice intuition pump. It takes a while to set up, because a lot of the jargon of artificial intelligence and computer science is unfamiliar to philosophers or other people. But if you have the patience to set some of these ideas up, then you can say, “Hey! Try thinking about the idea that what we have in
our heads is software. It’s a virtual machine, in the same way that a word processor is a virtual machine.” Suddenly, bells start ringing, and people start seeing things from a slightly different perspective.
[Dennett, Daniel C. “Intuition Pumps”. In: Brockman, John (ed.). The Third Culture: Beyond the Scientific Revolution. New York: Simon & Schuster. 1995]

* * *

Quando la scorsa primavera ho saputo dell’uscita del nuovo libro di Dennett e ne ho letto il titolo mi sono detto: «Bene, questa volta Dennett ci propone la cassetta degli attrezzi del pensatore, o del filosofo che dir si voglia». Non mi sbagliavo. In effetti, proprio nel primo capitolo, Dennett spiega i suoi intenti in modo particolarmente chiaro (già che ci siete, per favore, notate quanta distanza ci sia tra il chiaro e godibile Dennett di adesso e quello che cercava un lettore iniziato!). Lasciamo a lui la parola (abbiate pazienza, ma questa lunga citazione e sintesi del capitolo introduttivo è necessaria; soprattutto per voi che non avete ancora letto il libro, se posso essere un po’ paternalistico):

Thinking is hard. Thinking about some problems is so hard it can make your head ache just thinking about thinking about them. My colleague the neuropsychologist Marcel Kinsbourne suggests that whenever we find thinking hard, it is because the stony path to truth is competing with seductive, easier paths that turn out to be dead ends. Most of the effort in thinking is a matter of resisting these temptations. [pos. Kindle 161]
[…]
Some people, like von Neumann, are such natural geniuses that they can breeze through the toughest tangles; others are more plodding but are blessed with a heroic supply of “willpower” that helps them stay the course in their dogged pursuit of truth. Then there are the rest of us, not calculating prodigies and a little bit lazy, but still aspiring to understand whatever confronts us. What can we do? We can use thinking tools, by the dozens. These handy prosthetic imagination-extenders and focus-holders permit us to think reliably and even gracefully about really hard questions. This book is a collection of my favorite thinking tools. I will not just describe them; I intend to use them to move your mind gently through uncomfortable territory all the way to a quite radical vision of meaning, mind, and free will. We will begin with some tools that are simple and general, having applications to all sorts of topics. Some of these are familiar, but others have not been much noticed or discussed. Then I will introduce you to some tools that are for very special purposes indeed, designed to explode one specific seductive idea or another, clearing a way out of a deep rut that still traps and flummoxes experts. We will also encounter and dismantle a variety of bad thinking tools, misbegotten persuasion-devices that can lead you astray if you aren’t careful. Whether or not you arrive comfortably at my proposed destination – and decide to stay there with me – the journey will equip you with new ways of thinking about the topics, and thinking about thinking. [174-184]
[…]
Like all artisans, a blacksmith needs tools, but – according to an old (indeed almost extinct) observation – blacksmiths are unique in that they make their own tools. Carpenters don’t make their saws and hammers, tailors don’t make their scissors and needles, and plumbers don’t make their wrenches, but blacksmiths can make their hammers, tongs, anvils, and chisels out of their raw material, iron. What about thinking tools? Who makes them? And what are they made of? Philosophers have made some of the best of them – out of nothing but ideas, useful structures of information. René Descartes gave us Cartesian coordinates, the x- and y-axes without which calculus – a thinking tool par excellence simultaneously invented by Isaac Newton and the philosopher Gottfried Wilhelm Leibniz – would be almost unthinkable. Blaise Pascal gave us probability theory so we can easily calculate the odds of various wagers. The Reverend Thomas Bayes was also a talented mathematician, and he gave us Bayes’s theorem¸ the backbone of Bayesian statistical thinking. But most of the tools that feature in this book are simpler ones, not the precise, systematic machines of mathematics and science but the hand tools of the mind. Among them are
Labels. Sometimes just creating a vivid name for something helps you keep track of it while you turn it around in your mind trying to understand it. Among the most useful labels, as we shall see, are warning labels or alarms, which alert us to likely sources of error.
Examples. Some philosophers think that using examples in their work is, if not quite cheating, at least uncalled for –rather the way novelists shun illustrations in their novels. The novelists take pride in doing it all with words, and the philosophers take pride in doing it all with carefully crafted abstract generalizations presented in rigorous order, as close to mathematical proofs as they can muster. Good for them, but they can’t expect me to recommend their work to any but a few remarkable students. It’s just more difficult than it has to be.
Analogies and metaphors. Mapping the features of one complex thing onto the features of another complex thing that you already (think you) understand is a famously powerful thinking tool, but it is so powerful that it often leads thinkers astray when their imaginations get captured by a treacherous analogy.
Staging. You can shingle a roof, paint a house, or fix a chimney with the help of just a ladder, moving it and climbing, moving it and climbing, getting access to only a small part of the job at a time, but it’s often a lot easier in the end to take the time at the beginning to erect some sturdy staging that will allow you to move swiftly and safely around the whole project. Several of the most valuable thinking tools in this book are examples of staging that take some time to put in place but then permit a variety of problems to be tackled together – without all the ladder-moving.
And, finally, the sort of thought experiments I have dubbed intuition pumps. [193-216]
[…]
Other thought experiments are less rigorous but often just as effective: little stories designed to provoke a heartfelt, table-thumping intuition – “Yes, of course, it has to be so!” – about whatever thesis is being defended. I have called these intuition pumps. I coined the term in the first of my public critiques of philosopher John Searle’s famous Chinese Room thought experiment (Searle, 1980; Dennett, 1980), and some thinkers concluded I meant the term to be disparaging or dismissive. On the contrary, I love intuition pumps! That is, some intuition pumps are excellent, some are dubious, and only a few are downright deceptive. Intuition pumps have been a dominant force in philosophy for centuries. They are the philosophers’ version of Aesop’s fables, which have been recognized as wonderful thinking tools since before there were philosophers. If you ever studied philosophy in college, you were probably exposed to such classics as Plato’s cave, in The Republic, in which people are chained and can see only the shadows of real things cast on the cave wall; or his example, in Meno, of teaching geometry to the slave boy. Then there is Descartes’s evil demon, deceiving Descartes into believing in a world that was entirely illusory – the original Virtual Reality thought experiment – and Hobbes’s state of nature, in which life is nasty, brutish, and short. [227-235]
[…]
This self-conscious wariness with which we should approach any intuition pump is itself an important tool for thinking, the philosophers’ favorite tactic: “going meta” – thinking about thinking, talking about talking, reasoning about reasoning. Meta-language is the language we use to talk about another language, and meta-ethics is a bird’s-eye view examination of ethical theories. [276]
[…]
Some of the most powerful thinking tools are mathematical, but aside from mentioning them, I will not devote much space to them because this is a book celebrating the power of non-mathematical tools, informal tools, the tools of prose and poetry, if you like, a power that scientists often underestimate. [304]
[…]
I have always figured that if I can’t explain something I’m doing to a group of bright undergraduates, I don’t really understand it myself, and that challenge has shaped everything I have written. [322: non proprio sempre e non proprio tutto quello che ha scritto, come abbiamo toccato con mano; ma perdoniamogliela, questa piccola innocente bugia]
[…]
In the first section that follows, I present a dozen general, all-purpose tools, and then in subsequent sections I group the rest of the entries not by the type of tool but by the topic where the tool works best, turning first to the most fundamental philosophical topic – meaning, or content – followed by evolution, consciousness, and free will. A few of the tools I present are actual software, friendly devices that can do for your naked imagination what telescopes and microscopes can do for your naked eye.
Along the way, I will also introduce some false friends, tools that blow smoke instead of shining light. [354]

Ecco, il problema secondo me è tutto qui. Ho trovato la sezione dedicata agli all-purpose tools particolarmente azzeccata, e fedele al titolo del libro e al suo programma (è in effetti la seconda, A dozen general thinking tools, perché la prima Introduction: what is an intuition pump? è quella che ho appena riassunto). Poi è un progressivo calando, via via che l’attenzione si sposta dal tipo di strumento all’argomento al quale (secondo Dennett) quello strumento meglio si attaglia. Se sentite un po’ di puzza di bruciato, è perché il trucco c’è: poiché si tratta di argomenti di cui Dennett ha già scritto a lungo in passato, si resta con il dubbio che ci sia un po’ di riciclaggio e che alla fin fine a Dennett interessi soprattutto tornare sulle sue concezioni dell’evoluzione, della consciousness e del libero arbitrio.

Giusto per la cronaca: personalmente ho trovato nel libro un gradiente negativo. Le sezioni sono (dopo la prima e la seconda, di cui abbiamo già citato il titolo):

• Tools for thinking about meaning or content
• An interlude about computers
• More tools about meaning
• Tools for thinking about evolution
• Tools for thinking about consciousness
• Tools for thinking about free will
• What is it like to be a philosopher? (questa sezione è proprio appiccicata lì e non c’entra nulla con tutto quello che viene detto prima; forse Dennett è pagato a righe come Dumas?)
• Use the tools. Try Harder
• What got left out.

* * *

Se non siete sfiniti, avrei qualche citazione da proporvi.

Thought experiments are among the favorite tools of philosophers, not surprisingly. Who needs a lab when you can figure out the answer to your question by some ingenious deduction? Scientists, from Galileo to Einstein and beyond, have also used thought experiments to good effect, so these are not just philosophers’ tools. Some thought experiments are analyzable as rigorous arguments, often of the form reductio ad absurdum, in which one takes one’s opponents’ premises and derives a formal contradiction (an absurd result), showing that they can’t all be right. One of my favorites is the proof attributed to Galileo that heavy things don’t fall faster than lighter things (when friction is negligible). If they did, he argued, then since heavy stone A would fall faster than light stone B, if we tied B to A, stone B would act as a drag, slowing A down. But A tied to B is heavier than A alone, so the two together should also fall faster than A by itself. We have concluded that tying B to A would make something that fell both faster and slower than A by itself, which is a contradiction. [219: ne abbiamo parlato ampiamente qui]

There is a time and a place in philosophy for rigorous arguments, with all the premises numbered and the inference rules named, but these do not often need to be paraded in public. We ask our graduate students to prove they can do it in their dissertations, and some never outgrow the habit, unfortunately. And to be fair, the opposite sin of high-flown Continental rhetoric, larded with literary ornament and intimations of profundity, does philosophy no favors either. If I had to choose, I’d take the hard-bitten analytic logic-chopper over the deep purple sage every time. At least you can usually figure out what the logic-chopper is talking about and what would count as being wrong. [332: di quella che Dennett chiama Continental rhetoric, e che secondo me tende a essere specificamente francese, ho parlato recensendo La distinzione di Pierre Bourdieu]

How about dollars? These days the vast majority of them aren’t made of silver or even paper. They are virtual, made of information, not material, just like poems and promises. [1037]

Like our capacity to understand entirely novel sentences of our natural languages, sentences we have never before heard in our lives, our ability to make sense of the vast array of human interactions bespeaks a generative capacity that is to some degree innate in normal people. [1237]

Before there can be comprehension, there has to be competence without comprehension. [1536]

An algorithm is a certain sort of formal process that can be counted on – logically – to yield a certain sort of result whenever it is “run” or instantiated. [1999]

Three key features of algorithms will be important to us, and each is somewhat difficult to define.
(1) Substrate neutrality: The procedure for long division works equally well with pencil or pen, paper or parchment, neon lights or skywriting, using any symbol system you like. The power of the procedure is due to its logical structure, not the causal powers of the materials used in the instantiation, just so long as those causal powers permit the prescribed steps to be followed exactly.
(2) Underlying mindlessness: Although the overall design of the procedure may be brilliant, or yield brilliant results, each constituent step, and the transition between steps, is utterly simple. How simple? Simple enough for a dutiful idiot – or for a straightforward mechanical device – to perform. The standard textbook analogy notes that algorithms are recipes of sorts, designed to be followed by novice cooks. A recipe book written for great chefs might include the phrase “poach the fish in a suitable wine until almost done,” but an algorithm for the same process might begin “choose a white wine that says ‘dry’ on the label; take a corkscrew and open the bottle; pour an inch of wine in the bottom of a pan; turn the burner under the pan on high; …” – a tedious breakdown of the process into dead-simple steps, requiring no wise decisions or delicate judgments or intuitions on the part of the recipe-reader.
(3) Guaranteed results: Whatever it is that an algorithm does, it always does it, if it is executed without misstep. An algorithm is a foolproof recipe. [2009]

Aristotle said that God is the Unmoved Mover, and this doctrine announces that we are the Unmeant Meaners. [2195]

The job of a brain is to “produce future” in the form of anticipations about the things in the world that matter to guide the body in appropriate ways. Brains are energetically very expensive organs, and if they can’t do this important job well, they aren’t earning their keep. [2501]

Beethoven didn’t have to invent the symphony, which was already there for him to adapt, and Shakespeare didn’t have to invent the sonnet. [3052]

Huge distances must have been traversed since the dawn of Life with the earliest, simplest, self-replicating entities, spreading outward (diversity) and upward (excellence). [3163]

(Similarly, computers were not invented in order to make word-processing and the Internet possible, but once the space of possible computer applications was rendered accessible, design processes went into overdrive creating all the “species” we now rely on every day.) [3198]

[…] comprehension is the source of competence. [3223]

It is a mistake to confuse numbers with the numerals (Arabic or Roman or whatever) that we use as their names. Numerals are human inventions; numbers are not. [3252]

We should quell our desire to draw lines. We don’t need to draw lines. We can live with the quite unshocking and unmysterious fact that all these gradual changes accumulated over many millions of years and eventually produced undeniable mammals. [3328]

[…] hysterical realism. [3353]

The exploitation of accidents is the key to creativity, whether what is being made is a new genome, a new behavior, or a new melody. [3718]

Darwin’s “strange inversion of reasoning” is nicely echoed by Turing’s strange inversion of reasoning (Dennett, forthcoming): whereas we used to think (before Turing) that human competence had to flow from comprehension (that mysterious fount of intelligence), we now appreciate that comprehension itself is an effect created (bubbling up) from a host of competences piled on competences. [4471]

When physicist Richard Feynman found himself listening to a scientific talk in a field he didn’t know well, he had a favorite question to ask the speaker: Can you give me a really simple example of what you’re talking about? If the speaker couldn’t oblige, Feynman got suspicious, and rightly so. Did this person really have something to say, or was this just fancy technical talk parading as scientific wisdom? If you can’t make a hard problem relatively simple, you are probably not going about it the right way. Simplification is not just for beginners. [4922]

Be unpredictable, and look out for others following this advice! “Appreciation” of this principle can be seen in the widespread instinct found in animals who, when confronted with any complicated moving entity, try to treat it as an agent – “Who goes there, and what do you want?” not just “What’s that?” – in order to be safe, because maybe it is an agent and it wants to eat the animal, or to mate with it, or to fight over some prize. This instinctual response is the source in evolution of the invention of all the invisible elves, goblins, leprechauns, fairies, ogres, and gods that eventually evolve into God, the ultimate invisible intentional system (Dennett, 2006a). [5098]

But the genius of digitization is that all this fine structure is “ignored,” wiped out in the “correction to the norm.” When you have norms, like an alphabet, it doesn’t make any difference wHat f LAvOr the individual symbols have; they all read the same. In a computer it’s all 0s and 1s. [5221]

“Philosophy is garbage, but the history of garbage is scholarship.” [5806]

Proof of concept is a useful but dangerous bit of engineering jargon: asked to design a very sophisticated and complicated widget, you design a very simple widget – you solve what is nicely called a toy problem – and when it works on its stripped-down task, you declare that you have “proof of concept” and now it’s “just” a matter of scaling up to the fully competent widget that was requested, which will require only more time and money; the hard, conceptual problem has been “solved.” Sometimes this works just as advertised. [6680]

This excellent coinage is a computer hacker’s way of referring to a coding error at the semantic level, not the syntactic level. Leaving out a parenthesis is a typo; forgetting to declare a local variable is a thinko. In any human activity with a semantic or intentional interpretation, and clear canons of correctness or elegance, there is room for thinkos. Describing a lady as meretricious instead of meritorious is a thinko, not a typo. [6841]