Pyrrhonism

From Wikipedia, the free encyclopedia

Pyrrhonism is an Ancient Greek school of philosophical skepticism which rejects dogma and advocates the suspension of judgement over the truth of all beliefs. It was founded by Aenesidemus in the first century BCE, and said to have been inspired by the teachings of Pyrrho and Timon of Phlius in the fourth century BCE. Pyrrhonism is best known today through the surviving works of Sextus Empiricus, writing in the late second century or early third century CE. The publication of Sextus' works in the Renaissance ignited a revival of interest in Skepticism and played a major role in Reformation thought and the development of early modern philosophy.

History

Pyrrhonism is named after Pyrrho of Elis, a Greek philosopher in the 4th century BCE who was credited by the later Pyrrhonists with forming the first comprehensive school of skeptical thought. However, ancient testimony about the philosophical beliefs of the historical Pyrrho is minimal, and often contradictory: his teachings were recorded by his student Timon of Phlius, but those works have been lost, and only survive in fragments quoted by later authors, and based on testimonies of later authors such as Cicero, Pyrrho's own philosophy as recorded by Timon may have been much more dogmatic than that of the later school who bore his name. While Pyrrhonism would become the dominant form of skepticism in the early Roman period, in the Hellenistic period, the Platonic Academy was the primary advocate of skepticism until the mid-first century BCE, when Pyrrhonism as a philosophical school was founded by Aenesidemus.

Philosophy

As with other Hellenistic philosophies such as Stoicism, Peripateticism and Epicureanism, eudaimonia is the goal of Pyrrhonism. As with Epicureanism, Pyrrhonism places the attainment of ataraxia (a state of equanimity) as the way to achieve eudaimonia. Pyrrhonists dispute that the dogmatists – which includes all of Pyrrhonism's rival philosophies – claim to have found truth regarding non-evident matters, and that these opinions about non-evident matters (i.e., dogma) are what prevent one from attaining eudaimonia. For any of these dogma, a Pyrrhonist makes arguments for and against such that the matter cannot be concluded, thus suspending judgement, and thereby inducing ataraxia.

Pyrrhonists can be subdivided into those who are ephectic (engaged in suspension of judgment), aporetic (engaged in refutation) or zetetic (engaged in seeking). An ephectic merely suspends judgment on a matter, "balancing perceptions and thoughts against one another," It is a less aggressive form of skepticism, in that sometimes "suspension of judgment evidently just happens to the sceptic". An aporetic skeptic, in contrast, works more actively towards their goal, engaging in the refutation of arguments in favor of various possible beliefs in order to reach aporia, an impasse, or state of perplexity, which leads to suspension of judgement. Finally, the zetetic claims to be continually searching for the truth but to have thus far been unable to find it, and thus continues to suspend belief while also searching for reason to cease the suspension of belief.

Modes

Although Pyrrhonism's objective is ataraxia, it is best known for its epistemological arguments. The core practice is through setting argument against argument. To aid in this, the Pyrrhonist philosophers Aenesidemus and Agrippa developed sets of stock arguments known as "modes" or "tropes."

The ten modes of Aenesidemus

Aenesidemus is considered the creator of the ten tropes of Aenesidemus (also known as the ten modes of Aenesidemus)—although whether he invented the tropes or just systematized them from prior Pyrrhonist works is unknown. The tropes represent reasons for suspension of judgment. These are as follows:

1. Different animals manifest different modes of perception;
2. Similar differences are seen among individual men;
3. For the same man, information perceived with the senses is self-contradictory
4. Furthermore, it varies from time to time with physical changes
5. In addition, this data differs according to local relations
6. Objects are known only indirectly through the medium of air, moisture, etc.
7. These objects are in a condition of perpetual change in colour, temperature, size and motion
8. All perceptions are relative and interact one upon another
9. Our impressions become less critical through repetition and custom
10. All men are brought up with different beliefs, under different laws and social conditions

According to Sextus, superordinate to these ten modes stand three other modes: that based on the subject who judges (modes 1, 2, 3 & 4), that based on the object judged (modes 7 & 10), that based on both subject who judges and object judged (modes 5, 6, 8 & 9), and superordinate to these three modes is the mode of relation.

The five modes of Agrippa

These "tropes" or "modes" are given by Sextus Empiricus in his Outlines of Pyrrhonism. According to Sextus, they are attributed only "to the more recent skeptics" and it is by Diogenes Laërtius that we attribute them to Agrippa. The five tropes of Agrippa are:

1. Dissent – The uncertainty demonstrated by the differences of opinions among philosophers and people in general.
2. Infinite regress – All proof rests on matters themselves in need of proof, and so on to infinity.
3. Relation – All things are changed as their relations become changed, or, as we look upon them from different points of view.
4. Assumption – The truth asserted is based on an unsupported assumption.
5. Circularity – The truth asserted involves a circularity of proofs.

According to the mode deriving from dispute, we find that undecidable dissension about the matter proposed has come about both in ordinary life and among philosophers. Because of this we are not able to choose or to rule out anything, and we end up with suspension of judgement. In the mode deriving from infinite regress, we say that what is brought forward as a source of conviction for the matter proposed itself needs another such source, which itself needs another, and so ad infinitum, so that we have no point from which to begin to establish anything, and suspension of judgement follows. In the mode deriving from relativity, as we said above, the existing object appears to be such-and-such relative to the subject judging and to the things observed together with it, but we suspend judgement on what it is like in its nature. We have the mode from hypothesis when the Dogmatists, being thrown back ad infinitum, begin from something which they do not establish but claim to assume simply and without proof in virtue of a concession. The reciprocal mode occurs when what ought to be confirmatory of the object under investigation needs to be made convincing by the object under investigation; then, being unable to take either in order to establish the other, we suspend judgement about both.

With reference to these five tropes, that the first and third are a short summary of the earlier Ten Modes of Aenesidemus. The three additional ones show a progress in the Pyrrhonist system, building upon the objections derived from the fallibility of sense and opinion to more abstract and metaphysical grounds. According to Victor Brochard "the five tropes can be regarded as the most radical and most precise formulation of skepticism that has ever been given. In a sense, they are still irresistible today."

Criteria of action

Pyrrhonist decision making is made according to what the Pyrrhonists describe as the criteria of action holding to the appearances, without beliefs in accord with the ordinary regimen of life based on:

1. the guidance of nature, by which we are naturally capable of sensation and thought
2. the compulsion of the passions by which hunger drives us to food and thirst makes us drink
3. the handing down of customs and laws by which we accept that piety in the conduct of life is good and impiety bad
4. instruction in techne

Skeptic sayings

The Pyrrhonists devised several sayings (Greek ΦΩΝΩΝ) to help practitioners bring their minds to suspend judgment. Among these are:

• Not more, nothing more (a saying attributed to Democritus)
• Non-assertion (aphasia)
• Perhaps, it is possible, maybe
• I withhold assent
• I determine nothing (Montaigne created a variant of this as his own personal motto, "Que sais-je?" – "what do I know?")
• Everything is indeterminate
• Everything is non-apprehensible
• I do not apprehend
• To every argument an equal argument is opposed

Texts

Except for the works of Sextus Empiricus, the texts of ancient Pyrrhonism have been lost. There is a summary of the Pyrrhonian Discourses by Aenesidemus, preserved by Photius, and a brief summary of Pyrrho's teaching by Aristocles, quoting Pyrrho's student Timon preserved by Eusebius:

'The things themselves are equally indifferent, and unstable, and indeterminate, and therefore neither our senses nor our opinions are either true or false. For this reason then we must not trust them, but be without opinions, and without bias, and without wavering, saying of every single thing that it no more is than is not, or both is and is not, or neither is nor is not.

Influence

In Ancient Greek philosophy

Skeptics in Raphael's School of Athens painting. Pyrrho is #4 and Timon #5

Pyrrhonism is often contrasted with Academic skepticism, a similar but distinct form of Hellenistic philosophical skepticism. While early Academic skepticism was influenced in part by Pyrrho, it grew more and more dogmatic until Aenesidemus broke with the Academics to revive Pyrrhonism in the first century BCE, denouncing the Academy as "Stoics fighting against Stoics." Some later Pyrrhonists, such as Sextus Empiricus, go so far as to claim that Pyrrhonists are the only real skeptics, dividing all philosophy into the dogmatists, the Academics, and the skeptics. Dogmatists claim to have knowledge, Academic skeptics claim that knowledge is impossible, while Pyrrhonists assent to neither proposition, suspending judgment on both. The second century Roman historian Aulus Gellius describes the distinction as "...the Academics apprehend (in some sense) the very fact that nothing can be apprehended, and they determine (in some sense) that nothing can be determined, whereas the Pyrrhonists assert that not even that seems to be true, since nothing seems to be true.^"

Sextus Empiricus also said that the Pyrrhonist school influenced and had substantial overlap with the Empiric school of medicine, but that Pyrrhonism had more in common with the Methodic school in that it "follow[s] the appearances and take[s] from these whatever seems expedient."

Although Julian the Apostate mentions that Pyrrhonism had died out at the time of his writings, other writers mention the existence of later Pyrrhonists. Pseudo-Clement, writing around the same time (c. 300-320 CE) mentions Pyrrhonists in his Homilies and Agathias even reports a Pyrrhonist named Uranius as late as the middle of the 6th century CE.

Similarities between Pyrrhonism and Indian philosophy

Nagarjuna, a Madhyamaka Buddhist philosopher whose skeptical arguments are similar to those preserved in the work of Sextus Empiricus

A number of similarities have been noted between the Pyrrhonist works of Sextus Empiricius and that of Nagarjuna, the Madhyamaka Buddhist philosopher from the 2nd or 3rd century CE. Buddhist philosopher Jan Westerhoff says "many of Nāgārjuna's arguments concerning causation bear strong similarities to classical sceptical arguments as presented in the third book of Sextus Empiricus's Outlines of Pyrrhonism," and Thomas McEvilley suspects that Nagarjuna may have been influenced by Greek Pyrrhonist texts imported into India. McEvilley argues for mutual iteration in the Buddhist logico-epistemological traditions between Pyrrhonism and Madhyamika:

An extraordinary similarity, that has long been noticed, between Pyrrhonism and Mādhyamika is the formula known in connection with Buddhism as the fourfold negation (Catuṣkoṭi) and which in Pyrrhonic form might be called the fourfold indeterminacy.

McEvilley also notes a correspondence between the Pyrrhonist and Madhyamaka views about truth, comparing Sextus' account of two criteria regarding truth, one which judges between reality and unreality, and another which we use as a guide in everyday life. By the first criteria, nothing is either true or false, but by the second, information from the senses may be considered either true or false for practical purposes. As Edward Conze has noted, this is similar to the Madhyamika Two Truths doctrine, a distinction between "Absolute truth" (paramārthasatya), "the knowledge of the real as it is without any distortion," and "Truth so-called" (saṃvṛti satya), "truth as conventionally believed in common parlance.

Map of Alexander the Great's empire and the route he and Pyrrho took to India

Some scholars have also looked farther back, to determine if any earlier Indian philosophy may have had an influence on Pyrrho. Diogenes Laërtius' biography of Pyrrho reports that Pyrrho traveled with Alexander the Great's army to India and incorporated what he learned from the Gymnosophists and the Magi that he met in his travels into his philosophical system. Pyrrho would have spent about 18 months in Taxila as part of Alexander the Great's court during Alexander's conquest of the east. Christopher I. Beckwith draws comparisons between the Buddhist three marks of existence and the concepts outlined in the "Aristocles Passage".

However, other scholars, such as Stephen Batchelor and Charles Goodman question Beckwith's conclusions about the degree of Buddhist influence on Pyrrho. Conversely, while critical of Beckwith's ideas, Kuzminsky sees credibility in the hypothesis that Pyrrho was influenced by Buddhism, even if it cannot be safely ascertained with our current information.

While discussing Christopher Beckwith's claims in Greek Buddha: Pyrrho's Encounter with Early Buddhism in Central Asia, Jerker Blomqvist states that:

On the other hand, certain elements that are generally regarded as essential features of Buddhism are entirely absent from ancient Pyrrhonism/scepticism. The concepts of good and bad karma must have been an impossibility in the Pyrrhonist universe, if "things" were ἀδιάφορα, 'without a logical self-identity', and, consequently, could not be differentiated from each other by labels such as 'good' and 'bad' or 'just' and 'unjust'. A doctrine of rebirth, reminiscent of the Buddhist one, though favored by Plato and Pythagoras, was totally alien to the Pyrrhonists. The ἀταραξία, 'undisturbedness', that the Pyrrhonists promised their followers, may have a superficial resemblance to the Buddhist nirvana, but ἀταραξία, unlike nirvana, did not involve a liberation from a cycle of reincarnation; rather, it was a mode of life in this world, blessed with μετριοπάθεια, 'moderation of feeling' or 'moderate suffering', not with the absence of any variety of pain. Kuzminski, whom Beckwith hails as a precursor of his, had largely ignored the problem with this disparity between Buddhism and Pyrrhonism.

Ajñana, which upheld radical skepticism, may have been a more powerful influence on Pyrrho than Buddhism. The Buddhists referred to Ajñana's adherents as Amarāvikkhepikas or "eel-wrigglers", due to their refusal to commit to a single doctrine. Scholars including Barua, Jayatilleke, and Flintoff, contend that Pyrrho was influenced by, or at the very least agreed with, Indian skepticism rather than Buddhism or Jainism, based on the fact that he valued ataraxia, which can be translated as "freedom from worry". Jayatilleke, in particular, contends that Pyrrho may have been influenced by the first three schools of Ajñana, since they too valued freedom from worry.

Modern

Balance scales in equal balance are a modern symbol of Pyrrhonism

The recovery and publication of the works of Sextus Empiricus, particularly a widely influential translation by Henri Estienne published in 1562, ignited a revival of interest in Pyrrhonism. Philosophers of the time used his works to source their arguments on how to deal with the religious issues of their day. Major philosophers such as Michel de Montaigne, Marin Mersenne, and Pierre Gassendi later drew on the model of Pyrrhonism outlined in Sextus Empiricus' works for their own arguments. This resurgence of Pyrrhonism has sometimes been called the beginning of modern philosophy. Montaigne adopted the image of a balance scale for his motto, which became a modern symbol of Pyrrhonism. It has also been suggested that Pyrrhonism provided the skeptical underpinnings that René Descartes drew from in developing his influential method of Cartesian doubt and the associated turn of early modern philosophy towards epistemology. In the 18th century, David Hume was also considerably influenced by Pyrrhonism, using "Pyrrhonism" as a synonym for "skepticism.".

Nietzsche was critical of Pyrrhonian ephectics.

Friedrich Nietzsche, however, criticized the "ephetics" of the Pyrrhonists as a flaw of early philosophers, who he characterized as "shy little blunderer[s] and milquetoast[s] with crooked legs" prone to overindulging "his doubting drive, his negating drive, his wait-and-see ('ephectic') drive, his analytical drive, his exploring, searching, venturing drive, his comparing, balancing drive, his will to neutrality and objectivity, his will to every sine ira et studio: have we already grasped that for the longest time they all went against the first demands of morality and conscience?"

Contemporary

Fallibilism is a modern, fundamental perspective of the scientific method, as put forth by Karl Popper and Charles Sanders Peirce, that all knowledge is, at best, an approximation, and that any scientist always must stipulate this in her or his research and findings. It is, in effect, a modernized extension of Pyrrhonism. Indeed, historic Pyrrhonists sometimes are described by modern authors as fallibilists and modern fallibilists sometimes are described as Pyrrhonists.

The term "neo-Pyrrhonism" is used to refer to modern Pyrrhonists such as Benson Mates and Robert Fogelin.

Platonism

 

From Wikipedia, the free encyclopedia

Head of Plato, Roman copy. The original was exhibited at the Academy after the death of the philosopher (348/347 BC).

Platonism is the philosophy of Plato and philosophical systems closely derived from it, though contemporary Platonists do not necessarily accept all doctrines of Plato. Platonism had a profound effect on Western thought. In its most basic fundamentals, Platonism affirms the existence of abstract objects, which are asserted to exist in a third realm distinct from both the sensible external world and from the internal world of consciousness, and is the opposite of nominalism. This can apply to properties, types, propositions, meanings, numbers, sets, truth values, and so on (see abstract object theory). Philosophers who affirm the existence of abstract objects are sometimes called Platonists; those who deny their existence are sometimes called nominalists. The terms "Platonism" and "nominalism" also have established senses in the history of philosophy. They denote positions that have little to do with the modern notion of an abstract object.

In a narrower sense, the term might indicate the doctrine of Platonic realism, a form of mysticism. The central concept of Platonism, a distinction essential to the Theory of Forms, is the distinction between the reality which is perceptible but unintelligible, associated with the flux of Heraclitus and studied by the likes of science, and the reality which is imperceptible but intelligible, associated with the unchanging being of Parmenides and studied by the likes of mathematics. Geometry was the main motivation of Plato, and this also shows the influence of Pythagoras. The Forms are typically described in dialogues such as the Phaedo, Symposium and Republic as perfect archetypes of which objects in the everyday world are imperfect copies. Aristotle's Third Man Argument is its most famous criticism in antiquity.

In the Republic the highest form is identified as the Form of the Good, the source of all other Forms, which could be known by reason. In the Sophist, a later work, the Forms being, sameness and difference are listed among the primordial "Great Kinds". Plato established the academy, and in the 3rd century BC, Arcesilaus adopted academic skepticism, which became a central tenet of the school until 90 BC when Antiochus added Stoic elements, rejected skepticism, and began a period known as Middle Platonism.

In the 3rd century AD, Plotinus added additional mystical elements, establishing Neoplatonism, in which the summit of existence was the One or the Good, the source of all things; in virtue and meditation the soul had the power to elevate itself to attain union with the One. Many Platonic notions were adopted by the Christian church which understood Plato's Forms as God's thoughts (a position also known as divine conceptualism), while Neoplatonism became a major influence on Christian mysticism in the West through Saint Augustine, Doctor of the Catholic Church, who was heavily influenced by Plotinus' Enneads, and in turn were foundations for the whole of Western Christian thought. Many ideas of Plato were incorporated by the Roman Catholic Church.

Philosophy

Plato holding his Timaeus, detail from the Vatican fresco The School of Athens

The primary concept is the Theory of Forms. The only true being is founded upon the forms, the eternal, unchangeable, perfect types, of which particular objects of moral and responsible sense are imperfect copies. The multitude of objects of sense, being involved in perpetual change, are thereby deprived of all genuine existence. The number of the forms is defined by the number of universal concepts which can be derived from the particular objects of sense. The following excerpt may be representative of Plato's middle period metaphysics and epistemology:

[Socrates:] "Since the beautiful is opposite of the ugly, they are two."

[Glaucon:] "Of course."
"And since they are two, each is one?"
"I grant that also."
"And the same account is true of the just and unjust, the good and the bad, and all the forms. Each of them is itself one, but because they manifest themselves everywhere in association with actions, bodies, and one another, each of them appears to be many."
"That's right."
"So, I draw this distinction: On one side are those you just now called lovers of sights, lovers of crafts, and practical people; on the other side are those we are now arguing about and whom one would alone call philosophers."
"How do you mean?"
"The lovers of sights and sounds like beautiful sounds, colors, shapes, and everything fashioned out of them, but their thought is unable to see and embrace the nature of the beautiful itself."
"That's for sure."
"In fact, there are very few people who would be able to reach the beautiful itself and see it by itself. Isn't that so?"
"Certainly."
"What about someone who believes in beautiful things, but doesn't believe in the beautiful itself and isn't able to follow anyone who could lead him to the knowledge of it? Don't you think he is living in a dream rather than a wakened state? Isn't this dreaming: whether asleep or awake, to think that a likeness is not a likeness but rather the thing itself that it is like?"
"I certainly think that someone who does that is dreaming."
"But someone who, to take the opposite case, believes in the beautiful itself, can see both it and the things that participate in it and doesn't believe that the participants are it or that it itself is the participants--is he living in a dream or is he awake?
"He's very much awake."

(Republic Bk. V, 475e-476d, translation G.M.A Grube)

Book VI of the Republic identifies the highest form as the Form of the Good, the cause of all other Ideas, and that on which the being and knowing of all other Forms is contingent. Conceptions derived from the impressions of sense can never give us the knowledge of true being; i.e. of the forms. It can only be obtained by the soul's activity within itself, apart from the troubles and disturbances of sense; that is to say, by the exercise of reason. Dialectic, as the instrument in this process, leading us to knowledge of the forms, and finally to the highest form of the Good, is the first of sciences. Later Neoplatonism, beginning with Plotinus, identified the Good of the Republic with the transcendent, absolute One of the first hypothesis of the Parmenides (137c-142a).

Platonist ethics is based on the Form of the Good. Virtue is knowledge, the recognition of the supreme form of the good. And, since in this cognition, the three parts of the soul, which are reason, spirit, and appetite, all have their share, we get the three virtues, Wisdom, Courage, and Moderation. The bond which unites the other virtues is the virtue of Justice, by which each part of the soul is confined to the performance of its proper function.

Platonism had a profound effect on Western thought. In many interpretations of the Timaeus Platonism, like Aristotelianism, poses an eternal universe, as opposed to the nearby Judaic tradition that the universe had been created in historical time, with its continuous history recorded. Unlike Aristotelianism, Platonism describes idea as prior to matter and identifies the person with the soul. Many Platonic notions secured a permanent place in Christianity.

At the heart of Plato's philosophy is the theory of the soul. Francis Cornford described the twin pillars of Platonism as being the theory of the Forms, on the one hand, and, on the other hand, the doctrine of the immortality of the soul. Indeed, Plato was the first person in the history of philosophy to believe that the soul was both the source of life and the mind. In Plato's dialogues, we find the soul playing many disparate roles. Among other things, Plato believes that the soul is what gives life to the body (which was articulated most of all in the Laws and Phaedrus) in terms of self-motion: to be alive is to be capable of moving yourself; the soul is a self-mover. He also thinks that the soul is the bearer of moral properties (i.e., when I am virtuous, it is my soul that is virtuous as opposed to, say, my body). The soul is also the mind: it is that which thinks in us.

We see this casual oscillation between different roles of the soul in many dialogues. First of all, in the Republic:

Is there any function of the soul that you could not accomplish with anything else, such as taking care of something (epimeleisthai), ruling, and deliberating, and other such things? Could we correctly assign these things to anything besides the soul, and say that they are characteristic (idia) of it?

No, to nothing else.

What about living? Will we deny that this is a function of the soul?

That absolutely is.

The Phaedo most famously caused problems to scholars who were trying to make sense of this aspect of Plato's theory of the soul, such as Broadie and Dorothea Frede.

More-recent scholarship has overturned this accusation arguing that part of the novelty of Plato's theory of the soul is that it was the first to unite the different features and powers of the soul that became commonplace in later ancient and medieval philosophy. For Plato, the soul moves things by means of its thoughts, as one scholar puts it, and accordingly, the soul is both a mover (i.e., the principle of life, where life is conceived of as self-motion) and a thinker.

History

Ancient philosophy

The Academy

Main article: Platonic Academy

 

Site of Plato's Academy in Athens

Platonism was originally expressed in the dialogues of Plato, in which the figure of Socrates is used to expound certain doctrines, that may or may not be similar to the thought of the historical Socrates, Plato's master. Plato delivered his lectures at the Platonic Academy, a precinct containing a sacred grove outside the walls of Athens. The school continued there long after Plato's death. There were three periods: the Old, Middle, and New Academy. The chief figures in the Old Academy were Speusippus (Plato's nephew), who succeeded him as the head of the school (until 339 BC), and Xenocrates (until 313 BC). Both of them sought to fuse Pythagorean speculations on number with Plato's theory of forms.

The Skeptical Academy

Main article: Academic skepticism

Around 266 BC, Arcesilaus became head of the academy. This phase, known as the Middle Academy, strongly emphasized philosophical skepticism. It was characterized by its attacks on the Stoics and their assertion of the certainty of truth and our knowledge of it. The New Academy began with Carneades in 155 BC, the fourth head in succession from Arcesilaus. It was still largely skeptical, denying the possibility of knowing an absolute truth; both Arcesilaus and Carneades argued that they were maintaining a genuine tenet of Plato.

Middle Platonism

Main article: Middle Platonism

Around 90 BC, Antiochus of Ascalon rejected skepticism, making way for the period known as Middle Platonism, in which Platonism was fused with certain Peripatetic and many Stoic dogmas. In Middle Platonism, the Platonic Forms were not transcendent but immanent to rational minds, and the physical world was a living, ensouled being, the World-Soul. Pre-eminence in this period belongs to Plutarch. The eclectic nature of Platonism during this time is shown by its incorporation into Pythagoreanism (Numenius of Apamea) and into Jewish philosophy (Philo of Alexandria).

Neoplatonism

Main article: Neoplatonism

 

Many Western churchmen, including Augustine of Hippo, have been influenced by Platonism.

In the third century, Plotinus recast Plato's system, establishing Neoplatonism, in which Middle Platonism was fused with mysticism. At the summit of existence stands the One or the Good, as the source of all things. It generates from itself, as if from the reflection of its own being, reason, the nous, wherein is contained the infinite store of ideas. The world-soul, the copy of the nous, is generated by and contained in it, as the nous is in the One, and, by informing matter in itself nonexistent, constitutes bodies whose existence is contained in the world-soul. Nature therefore is a whole, endowed with life and soul. Soul, being chained to matter, longs to escape from the bondage of the body and return to its original source. In virtue and philosophical thought it has the power to elevate itself above the reason into a state of ecstasy, where it can behold, or ascend to, that one good primary Being whom reason cannot know. To attain this union with the Good, or God, is the true function of human beings.

Plotinus' disciple, Porphyry, followed by Iamblichus, developed the system in conscious opposition to Christianity. The Platonic Academy was re-established during this period; its most renowned head was Proclus (died 485), a celebrated commentator on Plato's writings. The academy persisted until Roman emperor Justinian closed it in 529.

Medieval philosophy

Christianity and Platonism

Main article: Neoplatonism and Christianity

Platonism has had some influence on Christianity through Clement of Alexandria and Origen, and the Cappadocian Fathers. St. Augustine was heavily influenced by Platonism as well, which he encountered through the Latin translations of Marius Victorinus of the works of Porphyry and/or Plotinus.

Platonism was considered authoritative in the Middle Ages. Platonism also influenced both Eastern and Western mysticism. Meanwhile, Platonism influenced various philosophers. While Aristotle became more influential than Plato in the 13th century, St. Thomas Aquinas's philosophy was still in certain respects fundamentally Platonic.

Modern philosophy

Renaissance

The Renaissance also saw a renewed interest in Platonic thought, including more interest in Plato himself. In 16th-, 17th-, and 19th-century England, Plato's ideas influenced many religious thinkers including the Cambridge Platonists. Orthodox Protestantism in continental Europe, however, distrusts natural reason and has often been critical of Platonism. An issue in the reception of Plato in early modern Europe was how to deal with the same-sex elements of his corpus.

Christoplatonism is a term used to refer to a dualism opined by Plato, which holds spirit is good but matter is evil, which influenced some christian churches, though the Bible's teaching directly contradicts this philosophy and thus it receives constant criticism from many teachers in the Christian Church today. According to the Methodist Church, Christoplatonism directly "contradicts the Biblical record of God calling everything He created good."

Contemporary philosophy

Modern Platonism

See also: Mathematical Platonism, Abstractionist Platonism, Abstract structuralism, and Platonized naturalism

Apart from historical Platonism originating from thinkers such as Plato and Plotinus, we also encounter the theory of abstract objects in the modern sense.

Platonism is the view that there exist such things as abstract objects — where an abstract object is an object that does not exist in space or time and which is therefore entirely non-physical and non-mental. Platonism in this sense is a contemporary view.

Most contemporary Platonists trace their views to those of Gottlob Frege.

This modern Platonism has been endorsed in one way or another at one time or another by numerous philosophers, such as Bernard Bolzano, who argue for anti-psychologism. Plato's works have been decisively influential for 20th century philosophers such as Alfred North Whitehead and his Process Philosophy; and for the critical realism and metaphysics of Nicolai Hartmann.

Analytic

In contemporary philosophy, most Platonists trace their ideas to Gottlob Frege's influential paper "Thought", which argues for Platonism with respect to propositions, and his influential book, The Foundations of Arithmetic, which argues for Platonism with respect to numbers and is a seminal text of the logicist project. Contemporary analytic philosophers who espoused Platonism in metaphysics include Bertrand Russell, Alonzo Church, Kurt Gödel, W. V. O. Quine, David Kaplan, Saul Kripke, Edward Zalta and Peter van Inwagen. Iris Murdoch espoused Platonism in moral philosophy in her 1970 book The Sovereignty of Good.

Paul Benacerraf's epistemological challenge to contemporary Platonism has proved its most influential criticism.

Continental

In contemporary Continental philosophy, Edmund Husserl's arguments against psychologism are believed to derive from a Platonist conception of logic, influenced by Frege and his mentor Bolzano.Husserl explicitly mentioned Bolzano, G. W. Leibniz and Hermann Lotze as inspirations for his position in his Logical Investigations (1900–1). Other prominent contemporary Continental philosophers interested in Platonism in a general sense include Leo Strauss, Simone Weil, and Alain Badiou.

Eliminative materialism

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Eliminativists argue that modern belief in the existence of mental phenomena is analogous to the ancient belief in obsolete theories such as the geocentric model of the universe.

Eliminative materialism (also called eliminativism) is a materialist position in the philosophy of mind. It is the idea that the majority of mental states in folk psychology do not exist. Some supporters of eliminativism argue that no coherent neural basis will be found for many everyday psychological concepts such as belief or desire, since they are poorly defined. The argument is that psychological concepts of behavior and experience should be judged by how well they reduce to the biological level. Other versions entail the nonexistence of conscious mental states such as pain and visual perceptions.

Eliminativism about a class of entities is the view that the class of entities does not exist. For example, materialism tends to be eliminativist about the soul; modern chemists are eliminativist about phlogiston; and modern physicists are eliminativist about luminiferous ether. Eliminative materialism is the relatively new (1960s–70s) idea that certain classes of mental entities that common sense takes for granted, such as beliefs, desires, and the subjective sensation of pain, do not exist. The most common versions are eliminativism about propositional attitudes, as expressed by Paul and Patricia Churchland, and eliminativism about qualia (subjective interpretations about particular instances of subjective experience), as expressed by Daniel Dennett, Georges Rey, and Jacy Reese Anthis. These philosophers often appeal to an introspection illusion.

In the context of materialist understandings of psychology, eliminativism is the opposite of reductive materialism, arguing that mental states as conventionally understood do exist, and directly correspond to the physical state of the nervous system. An intermediate position, revisionary materialism, often argues the mental state in question will prove to be somewhat reducible to physical phenomena—with some changes needed to the commonsense concept.

Since eliminative materialism arguably claims that future research will fail to find a neuronal basis for various mental phenomena, it may need to wait for science to progress further. One might question the position on these grounds, but philosophers like Churchland argue that eliminativism is often necessary in order to open the minds of thinkers to new evidence and better explanations. Views closely related to eliminativism include illusionism and quietism.

Overview

Various arguments have been made for and against eliminative materialism over the last 50 years. The view's history can be traced to David Hume, who rejected the idea of the "self" on the grounds that it was not based on any impression. Most arguments for the view are based on the assumption that people's commonsense view of the mind is actually an implicit theory. It is to be compared and contrasted with other scientific theories in its explanatory success, accuracy, and ability to predict the future. Eliminativists argue that commonsense "folk" psychology has failed and will eventually need to be replaced by explanations derived from neuroscience. These philosophers therefore tend to emphasize the importance of neuroscientific research as well as developments in artificial intelligence.

Philosophers who argue against eliminativism may take several approaches. Simulation theorists, like Robert Gordon and Alvin Goldman, argue that folk psychology is not a theory, but depends on internal simulation of others, and therefore is not subject to falsification in the same way that theories are. Jerry Fodor, among others, argues that folk psychology is, in fact, a successful (even indispensable) theory. Another view is that eliminativism assumes the existence of the beliefs and other entities it seeks to "eliminate" and is thus self-refuting.

Schematic overview: Eliminativists suggest that some sciences can be reduced (blue), but that theories that are in principle irreducible will eventually be eliminated (orange).

Eliminativism maintains that the commonsense understanding of the mind is mistaken, and that neuroscience will one day reveal that mental states talked about in everyday discourse, using words such as "intend", "believe", "desire", and "love", do not refer to anything real. Because of the inadequacy of natural languages, people mistakenly think that they have such beliefs and desires. Some eliminativists, such as Frank Jackson, claim that consciousness does not exist except as an epiphenomenon of brain function; others, such as Georges Rey, claim that the concept will eventually be eliminated as neuroscience progresses. Consciousness and folk psychology are separate issues, and it is possible to take an eliminative stance on one but not the other. The roots of eliminativism go back to the writings of Wilfred Sellars, W.V.O. Quine, Paul Feyerabend, and Richard Rorty. The term "eliminative materialism" was first introduced by James Cornman in 1968 while describing a version of physicalism endorsed by Rorty. The later Ludwig Wittgenstein was also an important inspiration for eliminativism, particularly with his attack on "private objects" as "grammatical fictions".

Early eliminativists such as Rorty and Feyerabend often confused two different notions of the sort of elimination that the term "eliminative materialism" entailed. On the one hand, they claimed, the cognitive sciences that will ultimately give people a correct account of the mind's workings will not employ terms that refer to commonsense mental states like beliefs and desires; these states will not be part of the ontology of a mature cognitive science. But critics immediately countered that this view was indistinguishable from the identity theory of mind. Quine himself wondered what exactly was so eliminative about eliminative materialism:

Is physicalism a repudiation of mental objects after all, or a theory of them? Does it repudiate the mental state of pain or anger in favor of its physical concomitant, or does it identify the mental state with a state of the physical organism (and so a state of the physical organism with the mental state)?

On the other hand, the same philosophers claimed that commonsense mental states simply do not exist. But critics pointed out that eliminativists could not have it both ways: either mental states exist and will ultimately be explained in terms of lower-level neurophysiological processes, or they do not. Modern eliminativists have much more clearly expressed the view that mental phenomena simply do not exist and will eventually be eliminated from people's thinking about the brain in the same way that demons have been eliminated from people's thinking about mental illness and psychopathology.

While it was a minority view in the 1960s, eliminative materialism gained prominence and acceptance during the 1980s. Proponents of this view, such as B.F. Skinner, often made parallels to previous superseded scientific theories (such as that of the four humours, the phlogiston theory of combustion, and the vital force theory of life) that have all been successfully eliminated in attempting to establish their thesis about the nature of the mental. In these cases, science has not produced more detailed versions or reductions of these theories, but rejected them altogether as obsolete. Radical behaviorists, such as Skinner, argued that folk psychology is already obsolete and should be replaced by descriptions of histories of reinforcement and punishment. Such views were eventually abandoned. Patricia and Paul Churchland argued that folk psychology will be gradually replaced as neuroscience matures.

Eliminativism is not only motivated by philosophical considerations, but is also a prediction about what form future scientific theories will take. Eliminativist philosophers therefore tend to be concerned with data from the relevant brain and cognitive sciences. In addition, because eliminativism is essentially predictive in nature, different theorists can and often do predict which aspects of folk psychology will be eliminated from folk psychological vocabulary. None of these philosophers are eliminativists tout court.

Today, the eliminativist view is most closely associated with the Churchlands, who deny the existence of propositional attitudes (a subclass of intentional states), and with Daniel Dennett, who is generally considered an eliminativist about qualia and phenomenal aspects of consciousness. One way to summarize the difference between the Churchlands' view and Dennett's is that the Churchlands are eliminativists about propositional attitudes, but reductionists about qualia, while Dennett is an anti-reductionist about propositional attitudes and an eliminativist about qualia.

More recently, Brian Tomasik and Jacy Reese Anthis have made various arguments for eliminativism.^[ Elizabeth Irvine has argued that both science and folk psychology do not treat mental states as having phenomenal properties so the hard problem "may not be a genuine problem for non-philosophers (despite its overwhelming obviousness to philosophers), and questions about consciousness may well 'shatter' into more specific questions about particular capacities." In 2022, Anthis published Consciousness Semanticism: A Precise Eliminativist Theory of Consciousness, which asserts that "formal argumentation from precise semantics" dissolves the hard problem because of the contradiction between precision implied in philosophical theory and the vagueness in its definition, which implies there is no fact of the matter for phenomenological consciousness.

Arguments for eliminativism

Problems with folk theories

Eliminativists such as Paul and Patricia Churchland argue that folk psychology is a fully developed but non-formalized theory of human behavior. It is used to explain and make predictions about human mental states and behavior. This view is often referred to as the theory of mind or just simply theory-theory, for it theorizes the existence of an unacknowledged theory. As a theory in the scientific sense, eliminativists maintain, folk psychology must be evaluated on the basis of its predictive power and explanatory success as a research program for the investigation of the mind/brain.

Such eliminativists have developed different arguments to show that folk psychology is a seriously mistaken theory and should be abolished. They argue that folk psychology excludes from its purview or has traditionally been mistaken about many important mental phenomena that can and are being examined and explained by modern neuroscience. Some examples are dreaming, consciousness, mental disorders, learning processes, and memory abilities. Furthermore, they argue, folk psychology's development in the last 2,500 years has not been significant and it is therefore stagnant. The ancient Greeks already had a folk psychology comparable to modern views. But in contrast to this lack of development, neuroscience is rapidly progressing and, in their view, can explain many cognitive processes that folk psychology cannot.

Folk psychology retains characteristics of now obsolete theories or legends from the past. Ancient societies tried to explain the physical mysteries of nature by ascribing mental conditions to them in such statements as "the sea is angry". Gradually, these everyday folk psychological explanations were replaced by more efficient scientific descriptions. Today, eliminativists argue, there is no reason not to accept an effective scientific account of cognition. If such an explanation existed, then there would be no need for folk-psychological explanations of behavior, and the latter would be eliminated the same way as the mythological explanations the ancients used.

Another line of argument is the meta-induction based on what eliminativists view as the disastrous historical record of folk theories in general. Ancient pre-scientific "theories" of folk biology, folk physics, and folk cosmology have all proven radically wrong. Eliminativists argue the same in the case of folk psychology. There seems no logical basis, to the eliminativist, to make an exception just because folk psychology has lasted longer and is more intuitive or instinctively plausible than other folk theories. Indeed, the eliminativists warn, considerations of intuitive plausibility may be precisely the result of the deeply entrenched nature in society of folk psychology itself. It may be that people's beliefs and other such states are as theory-laden as external perceptions and hence that intuitions will tend to be biased in their favor.

Specific problems with folk psychology

Much of folk psychology involves the attribution of intentional states (or more specifically as a subclass, propositional attitudes). Eliminativists point out that these states are generally ascribed syntactic and semantic properties. An example of this is the language of thought hypothesis, which attributes a discrete, combinatorial syntax and other linguistic properties to these mental phenomena. Eliminativists argue that such discrete, combinatorial characteristics have no place in neuroscience, which speaks of action potentials, spiking frequencies, and other continuous and distributed effects. Hence, the syntactic structures assumed by folk psychology have no place in such a structure as the brain. To this there have been two responses. On the one hand, some philosophers deny that mental states are linguistic and see this as a straw man argument. The other view is represented by those who subscribe to "a language of thought". They assert that mental states can be multiply realized and that functional characterizations are just higher-level characterizations of what happens at the physical level.

It has also been argued against folk psychology that the intentionality of mental states like belief imply that they have semantic qualities. Specifically, their meaning is determined by the things they are about in the external world. This makes it difficult to explain how they can play the causal roles they are supposed to in cognitive processes.

In recent years, this latter argument has been fortified by the theory of connectionism. Many connectionist models of the brain have been developed in which the processes of language learning and other forms of representation are highly distributed and parallel. This tends to indicate that such discrete and semantically endowed entities as beliefs and desires are unnecessary.

Physics eliminates intentionality

If a thought is a kind of neural process, then when one thinks about Paris, some network of neurons is somehow about Paris. Consider various accounts of this possibility. The neurons cannot be about Paris in the way a picture is, because unlike a picture, they do not resemble Paris. But neither can they be about Paris in the way that a red octagonal stop sign is about stopping even though it does not resemble that action. For a red octagon, or the word "stop" for that matter, only mean what they do as a matter of convention, only because we interpret the shapes in question as representing the action of stopping. And when you think about Paris, no one is assigning a conventional interpretation to such-and-such neurons in your brain so as to make them represent Paris. To suggest that some further brain process assigns such a meaning to the purported "Paris neurons" is merely to commit a homunculus fallacy and explains nothing. For if we say that one clump of neurons assigns meaning to another, we are saying that the one represents the other as having such-and-such a meaning. That means that we now have to explain how the first possesses the meaning or representational content by virtue of which it does that, which entails that we have not solved the first problem but only added a second one. We have "explained" the meaning of one clump of neurons by reference to meaning implicitly present in another clump, and thus merely initiated a vicious explanatory regress. The only way to break the regress is to postulate some bit of matter that just has its meaning intrinsically, without deriving it from anything else. But there can be no such bit of matter, because physics has ruled out the existence of clumps of matter of that sort.

Evolution eliminates intentionality

Any naturalistic, purely causal, non-semantic account of content must rely on Darwinian natural selection to build neural states capable of storing unique propositions, as required by folk psychology. Theories that attempt to account for intentionality within materialism face the disjunction problem, which results in the indeterminacy of propositional content. If such theories cannot solve the disjunction problem, then neurons cannot store unique propositions. The only process that can build neural circuits, evolution by natural selection, cannot solve the disjunction problem. The whole point of Darwin's theory is that in the creation of adaptations, nature is not active but passive. What is really going on is environmental filtration—a purely passive and not very discriminating process that prevents most traits below some minimal local threshold from persisting. Natural selection is selection against. Selection for requires foresight, planning, and purpose. Darwin's achievement was to show that the appearance of purpose belies the reality of purposeless, unforesighted, unplanned, mindless causation. All adaptation requires is selection against. That was Darwin's point. But the combination of blind variation and selection against is not possible without disjunctive outcomes.

It is important that selection against is not the contradictory of selection for, i.e. that selection against trait T is not just selection for trait not-T. This is because there are traits that are neither selected against nor selected for: the neutral ones that biologists, especially molecular evolutionary biologists, call silent, switched off, junk, non-coding, etc. Selection for and selection against are contraries, not contradictories.

Natural selection cannot discriminate between coextensive properties. To see how Darwinian selection against works in a real case, consider two distinct gene products, one of which is neutral or even harmful to an organism and the other of which is beneficial, that are coded for by adjacent genes on the chromosomes. This is the phenomenon of genetic linkage. The traits that the genes coded for will be coextensive in a population because the gene-types are coextensive in that population. Mendelian assortment and segregation do not break up these packages of genes with any efficiency. Only crossover, the breaking up and faulty re-annealing of chromosomal strings or similar processes, can do this. As Darwin realized, no process producing variants in nature picks up on future usefulness, convenience, need, or adaptational value. The only thing evolution (natural selection-against) can do about the free-riding maladaptive or neutral trait, whose genes are riding along close to the genes for an adaptive trait, is wait around for the genetic material to be broken at just the right place, between the genes. Once this happens, Darwinian processes can begin to tell the difference between them. But only when environmental vicissitudes break up the DNA on which the two adjacent genes sit can selection against get started—if one of the two proteins is harmful.

Darwinian theory's disjunction problem is that the process Darwin discovered cannot tell the difference between these two genes or their traits until crossover breaks the linkage between one gene, which is going to increase its frequency, and the other, which is going to decrease its frequency. If they are never separated, it will remain blind to their differences forever. What is worse, and more likely, one gene sequence can code for a favorable trait—a protein required for survival—while part of the same sequence can code for a maladaptive trait—some gene product that reduces fitness. Natural selection will have an even harder time discriminating between these two traits. Since evolution cannot solve the disjunction problem, the right conclusion for the materialist is to accept eliminativism by denying that neural states have as their informational content specific, particular, determinate statements that attribute non-disjunctive properties and relations to non-disjunctive subjects.

Arguments against eliminativism

Intentionality and consciousness are identical

Some eliminativists reject intentionality while accepting the existence of qualia. Other eliminativists reject qualia while accepting intentionality. Many philosophers argue that intentionality cannot exist without consciousness and vice versa, and so any philosopher who accepts one while rejecting the other is being inconsistent. They argue that, to be consistent, one must accept both qualia and intentionality or reject them both. Philosophers who argue for such a position include Philip Goff, Terence Horgan, Uriah Kriegal, and John Tienson. The philosopher Keith Frankish accepts the existence of intentionality but holds to illusionism about consciousness because he rejects qualia. Goff notes that beliefs are a kind of propositional thought.

Intuitive reservations

The thesis of eliminativism seems so obviously wrong to many critics, who find it undeniable that people know immediately and indubitably that they have minds, that argumentation seems unnecessary. This sort of intuition-pumping is illustrated by asking what happens when one asks oneself honestly if one has mental states. Eliminativists object to such a rebuttal of their position by claiming that intuitions often are mistaken. Analogies from the history of science are frequently invoked to buttress this observation: it may appear obvious that the sun travels around the earth, for example, but this was nevertheless proved wrong. Similarly, it may appear obvious that apart from neural events there are also mental conditions, but that could be false.

But even if one accepts the susceptibility to error of people's intuitions, the objection can be reformulated: if the existence of mental conditions seems perfectly obvious and is central to our conception of the world, then enormously strong arguments are needed to deny their existence. Furthermore, these arguments, to be consistent, must be formulated in a way that does not presuppose the existence of entities like "mental states", "logical arguments", and "ideas", lest they be self-contradictory. Those who accept this objection say that the arguments for eliminativism are far too weak to establish such a radical claim and that there is thus no reason to accept eliminativism.

Self-refutation

Some philosophers, such as Paul Boghossian, have attempted to show that eliminativism is in some sense self-refuting, since the theory presupposes the existence of mental phenomena. If eliminativism is true, then eliminativists must accept an intentional property like truth, supposing that in order to assert something one must believe it. Hence, for eliminativism to be asserted as a thesis, the eliminativist must believe that it is true; if so, there are beliefs, and eliminativism is false.

Georges Rey and Michael Devitt reply to this objection by invoking deflationary semantic theories that avoid analyzing predicates like "x is true" as expressing a real property. They are instead construed as logical devices, so that asserting that a sentence is true is just a quoted way of asserting the sentence itself. To say "'God exists' is true" is just to say "God exists". This way, Rey and Devitt argue, insofar as dispositional replacements of "claims" and deflationary accounts of "true" are coherent, eliminativism is not self-refuting.

Correspondence theory of truth

Several philosophers, such as the Churchlands and Alex Rosenberg, have developed a theory of structural resemblance or physical isomorphism that could explain how neural states can instantiate truth within the correspondence theory of truth. Neuroscientists use the word "representation" to identify the neural circuits' encoding of inputs from the peripheral nervous system in, for example, the visual cortex. But they use the word without according it any commitment to intentional content. In fact, there is an explicit commitment to describing neural representations in terms of structures of neural axonal discharges that are physically isomorphic to the inputs that cause them. Suppose that this way of understanding representation in the brain is preserved in the long-term course of research providing an understanding of how the brain processes and stores information. Then there will be considerable evidence that the brain is a neural network whose physical structure is identical to the aspects of its environment it tracks and whose representations of these features consist in this physical isomorphism.

Experiments in the 1980s with macaques isolated the structural resemblance between input vibrations the finger feels, measured in cycles per second, and representations of them in neural circuits, measured in action-potential spikes per second. This resemblance between two easily measured variables makes it unsurprising that they would be among the first such structural resemblances to be discovered. Macaques and humans have the same peripheral nervous system sensitivities and can make the same tactile discriminations. Subsequent research into neural processing has increasingly vindicated a structural resemblance or physical isomorphism approach to how information enters the brain and is stored and deployed.

This isomorphism between brain and world is not a matter of some relationship between reality and a map of reality stored in the brain. Maps require interpretation if they are to be about what they map, and eliminativism and neuroscience share a commitment to explaining the appearance of aboutness by purely physical relationships between informational states in the brain and what they "represent". The brain-to-world relationship must be a matter of physical isomorphism—sameness of form, outline, structure—that does not require interpretation.

This machinery can be applied to make "sense" of eliminativism in terms of the sentences eliminativists say or write. When we say that eliminativism is true, that the brain does not store information in the form of unique sentences, statements, expressing propositions or anything like them, there is a set of neural circuits that has no trouble coherently carrying this information. There is a possible translation manual that will guide us back from the vocalization or inscription eliminativists express to these circuits. These neural structures will differ from the neural circuits of those who explicitly reject eliminativism in ways that our translation manual will presumably shed some light on, giving us a neurological handle on disagreement and on the structural differences in neural circuitry, if any, between asserting p and asserting not-p when p expresses the eliminativist thesis.

Criticism

The physical isomorphism approach faces indeterminacy problems. Any given structure in the brain will be causally related to, and isomorphic in various respects to, many different structures in external reality. But we cannot discriminate the one it is intended to represent or that it is supposed to be true "of". These locutions are heavy with just the intentionality that eliminativism denies. Here is a problem of underdetermination or holism that eliminativism shares with intentionality-dependent theories of mind. Here, we can only invoke pragmatic criteria for discriminating successful structural representations—the substitution of true ones for unsuccessful ones—the ones we used to call false.

Dennett notes that it is possible that such indeterminacy problems remain only hypothetical, not occurring in reality. He constructs a 4x4 "Quinian crossword puzzle" with words that must satisfy both the across and down definitions. Since there are multiple constraints on this puzzle, there is one solution. Thus we can think of the brain and its relation to the external world as a very large crossword puzzle that must satisfy exceedingly many constraints to which there is only one possible solution. Therefore, in reality we may end up with only one physical isomorphism between the brain and the external world.

Pragmatic theory of truth

When indeterminacy problems arose because the brain is physically isomorphic to multiple structures of the external world, it was urged that a pragmatic approach be used to resolve the problem. Another approach argues that we the pragmatic theory of truth should be used from the start to decide whether certain neural circuits store true information about the external world. Pragmatism was founded by Charles Sanders Peirce and William James, and later refined by our understanding of the philosophy of science. According to pragmatism, to say that general relativity is true is to say that it makes more accurate predictions than other theories (Newtonian mechanics, Aristotle's physics, etc.). If computer circuits lack intentionality and do not store information using propositions, then in what sense can computer A have true information about the world while computer B lacks it? If the computers were instantiated in autonomous cars, we could test whether A or B successfully complete a cross-country road trip. If A succeeds while B fails, the pragmatist can say that A holds true information about the world, because A's information allows it to make more accurate predictions (relative to B) about the world and to move around its environment more successfully. Similarly, if brain A has information that enables the biological organism to make more accurate predictions about the world and helps the organism successfully move around in the environment, then A has true information about the world. Although not advocates of eliminativism, John Shook and Tibor Solymosi argue that pragmatism is a promising program for understanding advancements in neuroscience and integrating them into a philosophical picture of the world.

Criticism

The reason naturalism cannot be pragmatic in its epistemology starts with its metaphysics. Science tells us that we are components of the natural realm, indeed latecomers in the 13.8-billion-year-old universe. The universe was not organized around our needs and abilities, and what works for us is just a set of contingent facts that could have been otherwise. Among the sciences' explananda of the set of things that work for us. Once we have begun discovering things about the universe that work for us, science sets out to explain why they do. It is clear that one explanation for why things work for us that we must rule out as unilluminating, indeed question-begging, is that they work for us because they work for us. If something works for us, enables us to meet our needs and wants, there must be an explanation reflecting facts about us and the world that produce the needs and the means to satisfy them.

The explanation of why scientific methods work for us must be a causal explanation. It must show what facts about reality make the methods we employ to acquire knowledge suitable for doing so. The explanation must show that our methods work —for example, have reliable technological application— not by coincidence, still less miracle or accident. That means there must be some facts, events, processes that operate in reality and brought about our pragmatic success. The demand that success be explained is a consequence of science's epistemology. If the truth of such explanations consists in the fact that they work for us (as pragmatism requires), then the explanation of why our scientific methods work is that they work. That is not a satisfying explanation.

Qualia

Another problem for the eliminativist is the consideration that human beings undergo subjective experiences and hence their conscious mental states have qualia. Since qualia are generally regarded as characteristics of mental states, their existence does not seem compatible with eliminativism. Eliminativists such as Dennett and Rey respond by rejecting qualia. Opponents of eliminativism see this response as problematic, since many claim that existence of qualia is perfectly obvious. Many philosophers consider the "elimination" of qualia implausible, if not incomprehensible. They assert that, for instance, the existence of pain is simply beyond denial.

Admitting that the existence of qualia seems obvious, Dennett nevertheless holds that "qualia" is a theoretical term from an outdated metaphysics stemming from Cartesian intuitions. He argues that a precise analysis shows that the term is in the long run empty and full of contradictions. Eliminativism's claim about qualia is that there is no unbiased evidence for such experiences when regarded as something more than propositional attitudes. In other words, it does not deny that pain exists, but holds that it exists independently of its effect on behavior. Influenced by Wittgenstein's Philosophical Investigations, Dennett and Rey have defended eliminativism about qualia even when other aspects of the mental are accepted.

Quining qualia

Dennett offers philosophical thought experiments to argue that qualia do not exist. First he lists five properties of qualia:

1. They are "directly" or "immediately" graspable during our conscious experiences.
2. We are infallible about them.
3. They are "private": no one can directly access anyone else's qualia.
4. They are ineffable.
5. They are "intrinsic" and "simple" or "unanalyzable."

Inverted qualia

The first thought experiment Dennett uses to demonstrate that qualia lack the listed necessary properties to exist involves inverted qualia: consider two people who have different qualia but the same external physical behavior. But now the qualia supporter can present an "intrapersonal" variation. Suppose a neurosurgeon works on your brain and you discover that grass now looks red. Would this not be a case where we could confirm the reality of qualia—by noticing how the qualia have changed while every other aspect of our conscious experience remains the same? Not quite, Dennett replies via the next intuition pump, "alternative neurosurgery". There are two different ways the neurosurgeon might have accomplished the inversion. First, they might have tinkered with something "early on", so that signals from the eye when you look at grass contain the information "red" rather than "green". This would result in genuine qualia inversion. But they might instead have tinkered with your memory. Here your qualia would remain the same, but your memory would be altered so that your current green experience would contradict your earlier memories of grass. You would still feel that the color of grass had changed, but here the qualia have not changed, but your memories have. Would you be able to tell which of these scenarios is correct? No: your perceptual experience tells you that something has changed but not whether your qualia have changed. Dennett concludes, since (by hypothesis) the two surgical procedures can yield exactly the same introspective effects while only one inverts the qualia, nothing in the subject's experience can favor one hypothesis over the other. So unless he seeks outside help, the state of his own qualia must be as unknowable to him as the state of anyone else's. It is questionable, in short, that we have direct, infallible access to our conscious experience.

The experienced beer drinker

Dennett's second thought experiment involves beer. Many people think of beer as an acquired taste: one's first sip is often unpleasant, but one gradually comes to enjoy it. But wait, Dennett asks—what is the "it" here? Compare the flavor of that first taste with the flavor now. Does the beer taste exactly the same both then and now, only now you like that taste whereas before you disliked it? Or is it that the way beer tastes gradually shifts—so that the taste you did not like at the beginning is not the same taste you now like? In fact most people simply cannot tell which is the correct analysis. But that is to give up again on the idea that we have special and infallible access to our qualia. Further, when forced to choose, many people feel that the second analysis is more plausible. But then if one's reactions to an experience are in any way constitutive of it, the experience is not so "intrinsic" after all—and another qualia property falls.

Inverted goggles

Dennett's third thought experiment involves inverted goggles. Scientists have devised special eyeglasses that invert up and down for the wearer. When you put them on, everything looks upside down. When subjects first put them on, they can barely walk around without stumbling. But after subjects wear them for a while, something surprising occurs. They adapt and become able to walk around as easily as before. When you ask them whether they adapted by re-inverting their visual field or simply got used to walking around in an upside-down world, they cannot say. So as in our beer-drinking case, either we simply do not have the special, infallible access to our qualia that would allow us to distinguish the two cases or the way the world looks to us is actually a function of how we respond to the world—in which case qualia are not "intrinsic" properties of experience.

Criticism

Edward Feser objects to Dennett's position as follows. That you need to appeal to third-person neurological evidence to determine whether your memory of your qualia has been tampered with does not seem to show that your qualia themselves—past or present—can be known only by appealing to that evidence. You might still be directly aware of your qualia from the first-person, subjective point of view even if you do not know whether they are the same as the qualia you had yesterday—just as you might really be aware of the article in front of you even if you do not know whether it is the same as the article you saw yesterday. Questions about memory do not necessarily bear on the nature of your awareness of objects present here and now (even if they bear on what you can justifiably claim to know about such objects), whatever those objects happen to be. Dennett's assertion that scientific objectivity requires appealing exclusively to third-person evidence appears mistaken. What scientific objectivity requires is not denial of the first-person subjective point of view but rather a means of communicating inter-subjectively about what one can grasp only from that point of view. Given the relational structure first-person phenomena like qualia appear to exhibit—a structure that Carnap devoted great effort to elucidating—such a means seems available: we can communicate what we know about qualia in terms of their structural relations to one another. Dennett fails to see that qualia can be essentially subjective and still relational or non-intrinsic, and thus communicable. This communicability ensures that claims about qualia are epistemologically objective; that is, they can in principle be grasped and evaluated by all competent observers even though they are claims about phenomena that are arguably not metaphysically objective, i.e., about entities that exist only as grasped by a subject of experience. It is only the former sort of objectivity that science requires. It does not require the latter, and cannot plausibly require it if the first-person realm of qualia is what we know better than anything else.

Illusionism

Illusionism is an active program within eliminative materialism to explain phenomenal consciousness as an illusion. It is promoted by the philosophers Daniel Dennett, Keith Frankish, and Jay Garfield, and the neuroscientist Michael Graziano. Graziano has advanced the attention schema theory of consciousness and postulates that consciousness is an illusion. According to David Chalmers, proponents argue that once we can explain consciousness as an illusion without the need for a realist view of consciousness, we can construct a debunking argument against realist views of consciousness. This line of argument draws from other debunking arguments like the evolutionary debunking argument in the field of metaethics. Such arguments note that morality is explained by evolution without positing moral realism, so there is a sufficient basis to debunk moral realism.

Criticism

Illusionists generally hold that once it is explained why people believe and say they are conscious, the hard problem of consciousness will dissolve. Chalmers agrees that a mechanism for these beliefs and reports can and should be identified using the standard methods of physical science, but disagrees that this would support illusionism, saying that the datum illusionism fails to account for is not reports of consciousness but rather first-person consciousness itself. He separates consciousness from beliefs and reports about consciousness, but holds that a fully satisfactory theory of consciousness should explain how the two are "inextricably intertwined" so that their alignment does not require an inexplicable coincidence. Illusionism has also been criticized by the philosopher Jesse Prinz.

Efficacy of folk psychology

Some philosophers argue that folk psychology is quite successful. Simulation theorists doubt that people's understanding of the mental can be explained in terms of a theory at all. Rather they argue that people's understanding of others is based on internal simulations of how they would act and respond in similar situations. Jerry Fodor believes in folk psychology's success as a theory, because it makes for an effective way of communication in everyday life that can be implemented with few words. Such effectiveness could not be achieved with complex neuroscientific terminology.