The Nature of the Mind and its Ideas

Basic ideas philosophy of mind

philosophy of mind is a fascinating discipline that  studies the nature of the mind and tries to answer a host of questions like what is the real me? Am I the hands , legs or the head?How do we perceive is it just the five senses or only the brain? From where do feelings and emotions come from ? Is our behavior only governed only our genes?

You might think that psychology and neurology are better candidates for answering these questions, but we might also ask do ghosts and god have a mind? Are computers capable of thinking? do they have a mind ? Can they have emotions? 

Many of these are beyond the pale of empirical investigation.

Some philosophers and their thoughts about mind and matter

 The Cārvāka school of Indian philosophy rejected the existence of anything but matter (including God and the soul)--No mind only matter referred to as Monism

Substance Dualism is a common feature of several orthodox Hindu schools including the Sāṅkhya, Nyāya, Yoga and Dvaita Vedanta. In these schools a clear difference is drawn between matter and a non-material soul, which is eternal and undergoes samsara, a cycle of death and rebirth.

In the Advaita Vedanta of the 8th century Indian philosopher Śaṅkara, the mind, body and world are all held to be the same unchanging eternal conscious entity called Brahman. Advaita, which means non-dualism, holds the view that all that exists is pure absolute consciousness. Only mind (consciousness ) Monism

Buddhist teachings regard humans as made up of the five skandas -Body (rupa),Feelings (vedana) experienced through the body – pleasant, unpleasant or neutral
<B>Perceptions (sanna) – what we perceive through our body
<B>Formations (sankhara) – you could call this habits or metabolic processes or autonomic processes of the body.  You are not aware of these processes.
<B>Sense consciousness (vinnana) – this is the activity of our 6 senses (our 5 senses + our brain activity), e.g., sound hits our hearing system – it becomes active and sound consciousness arises.

consciousness arises from the interaction of body and senses. It is a process and not a substance. Unlike Descartes Buddhists don't see mind as a separate substance they see it as arising from the process of interaction. They rule out a disembodied consciousness such as that of Sankara. They reject the notion of Atman or soul.


Socrates was a mind-body dualist. This means he thought that the mind is composed of a different substance to the brain. 

As with Socrates, Plato's belief that the mind is separate from the body came from the need to explain human intellect, animals did not seem to possess anything similar and it couldn't be explained mechanically.

The forms explain how the mind interprets the continuous stream of sensory data it's exposed to by recognizing certain eternal concepts. If our intellect is composed of forms, then it is eternal and distinct from the body.

Plato did not believe that the mind exists in time or space and thought that it would return to the realm of the forms upon death.

Aristotle argued that the mind is a part of the human body, and so also rejected mind-body dualism. He did however, believe that intellect is different from any other part of the body. This is because our conscious range does not appear to be restricted in the way that our physical senses are.

Aristotle claimed that intellect does not have a corresponding bodily organ. This means that it does not exist in space, despite having a physical origin.

Cartesian Dualism

Descartes was a substance dualist. He beleived that mind and matter are two different substances. Here are some of the arguments he advanced in support of two different substance theory.

The Indivisibility Argument

This argument can be formulated as follows:

Premise 1. mind is indivisible by its very nature.

Premise 2. body is divisible by its very nature.

Conclusion 3. mind is completely different from the body.

There is an implicit
If two things are identical, then they have exactly the same properties.  (Leibniz's Law)

Quite apart from Leibniz's Law the reasoning is fallacious , by its very nature = by definition mind is indivisible and body is divisible. Cannot define divisibility to two entities and claim distinctness. By divisibility is meant that the essence is preserved even if a part is removed e.g if a man's hand or leg is removed he still continues to be the same person.

What is indivisibility of mind?

In sixth meditation Descartes writes "For in truth, when I consider the mind, that is, when I consider myself in so far only as I am a thinking thing, I can distinguish in myself no parts.." 

"I have a vivid and clear idea of •myself as something that thinks and isn’t extended, and one of •body as something that is extended and does not think. So it is certain that •I am really distinct from •my body and can exist without it"

Descartes is actually defining mind as "thinking thing without extension" so little wonder that it cannot be spatially divided because it is not extended in the first place. He also presupposes that the I of yesterday is the I of today and tomorrow. This continuity is denied by Buddhists for example.

a. Reference: Discourse Part 4 and Meditation II.

Argument from Doubt:

Premise 1. I can doubt that I have a body.

Premise 2. I cannot doubt that I am.

Conclusion 3. Therefore, I who am doubting and thinking am not a body.

There is an implicit
If two things are identical, then they have exactly the same properties.  (Leibniz's Law)

The Real Distinction Argument

Premise 1. I have a clear and distinct idea of the mind as a thinking, non-extended thing.

Premise 2.I have a clear and distinct idea of body as an extended, non-thinking thing.

Conclusion 3. the mind is really distinct from the body and can exist without it.

If you can measure something in space, as having a length, breadth, width etc., then it must be a material substance. If you can’t measure it, then it must be a thought-like substance.

So much for the why of dualism now let us look at the consequences of dualism, the problems arising from Cartesian dualism.

Cartesian Dualism - Problems

If mind and body are two different and distinct entities how does one account for the fact that body influences the mind and vice versa . If you ingest alcohol your thinking (mind) changes. If you are thinking great food you may salivate-secrete saliva in the mouth . Chronic stress , fear and anxiety can cause nausea . Pranayam a physical activity is known to reduce stress and calm the mind(mental activity). My arm moves when I will that it shall move, but my will is a mental phenomenon and the motion of my arm a physical phenomenon. The mental influences bodily movement.There are countless other examples.

How does Descartes account for these 
Men have a soul that resides in the pineal gland .There the soul comes in contact with the "vital spirits," and through this contact there is interaction between soul and body. However Descartes did not have a satisfactory answer . Geulincx a follower of Descartes  invented an answer, known as the theory of the "two clocks." Suppose you have two clocks which both keep perfect time: whenever one points to the hour, the other will strike, so that if you saw one and heard the other, you would think the one caused the other to strike.

 Since the physical series was rigidly determined by natural laws, the mental series, which
ran parallel to it, must be equally deterministic. And everyone knows that the mental series is hardly predictable.

Some Conclusions

According to Bertrand Russel "In the whole theory of the material world, Cartesian-ism was rigidly deterministic...The consequence was that all the movements of matter were determined by physical laws, and, owing to parallelism, mental events must be equally determinate. Consequently Cartesian s had difficulty about free will."

According to others Descartes says that our spirits, are not constrained by natural laws. Spirits reside in a non-physical realm, are made of non-physical stuff, and are beyond the domain of the laws of physics and chemistry. In this non-physical realm, our spirits have unbounded freedom, and it is our spirits that are ultimately behind the free actions that we perform.  Descartes’ version of dualism, then, accepts the rule of physical laws in the physical world, but embraces free will as an element of human spirits.

Descartes firmly believed in God and the soul’s immortality [ Descartes presumes that the mind and soul are more or less the same thing]. Complete absence of mentality from the nature of physical things is central to Descartes’ version of the new, mechanistic physics.

All in all Descartes highlighted several issues which are still being debated today.

References

1. https://philosophynow.org/issues/87/Philosophy_of_Mind_An_Overview
2. https://plato.stanford.edu/entries/descartes/
3. http://www.iep.utm.edu/descmind/
4. http://www.iep.utm.edu/dualism/
5. https://en.wikipedia.org/wiki/Philosophy_of_mind
6. https://askaphilosopher.wordpress.com/2011/07/22/descartes-argument-for-mind-body-dualism/
7. http://philosophyreaders.blogspot.in/2013/01/leibnizs-law.html
8. https://en.wikipedia.org/wiki/Identity_of_indiscernibles
9. http://www.philosophicaleggs.com/?p=391
10. https://askaphilosopher.wordpress.com/2011/07/22/descartes-argument-for-mind-body-dualism/
11. https://web.ics.purdue.edu/~curd/110WK13.html
12. https://www.utm.edu/staff/jfieser/class/120/4-freewill.htm

How do our minds know?

As I said in my first blog we will do a time-travel from pre-socratics to René Descartes. He was a man of many parts a  philosopher, mathematician, and scientist. We will dwell on his contributions to philosophy or rather how he founded the System named after him - Cartesian Dualism,

Brief Bio Descartes

Rene Descartes is often referred to as the father or founder of modern western philosophy. He lived from 31st March 1596 till 11th February 1650. To get an idea of the shift in time let us look at timeline.png.

Descartes's father was a councillor of the Parlement of Brittany, and possessed a moderate amount of landed property. Descartes inherited the property, and invested the money, obtaining an income of six or seven thousand francs a year. 

He was educated, from 1604 to 1612, at the Jesuit college of La Flèche,where he studied mathematics and physics. He studied two years (1615–16) at the University of Poitiers, and earned a Baccalauréat and Licence in Canon and Civil Law.

He joined the army and while still in the army came up with what every school boy today knows as cartesian coordinates and analytic geometry.

In 1626 he settled in Paris, but  moved to Holland, then a country at the height of its power, in 1628. He lived there for the next 20 years, devoting all his time and efforts to mathematics and philosophy and to the pursuit of truth. In 1649, at the invitation of the Queen of Sweden, he went to Stockholm to become the Queen's teacher, but he died a few months later, on February 11, 1650, of acute pneumonia.

We are concerned with Descates contributions to philosophy. His major works are Meditations, Discourse on Method and  Principles of philosophy.

Background

We take a brief look at How philosophers prior to Descartes tried to answer the question How do our minds know? What were their methods for attaining true knowledge? What was their idea of ultimate reality?

Let us digress to take a look at two important ideas. Epistemology and Ontology

Epistemology comes from the Greek "Episteme" and refers to knowledge, science or understanding.It studies the nature of knowledge, justification, and the rationality of belief. The four important areas are (1) the philosophical analysis of the nature of knowledge and how it relates to such concepts as truth, belief, and justification
 (2) various problems of skepticism,
 (3) the sources and scope of knowledge and justified belief, and 
(4) the criteria for knowledge and justification.

What's all this fuss? you might say we acquire knowledge by studying for a degree. But then what exactly is knowledge? Is it the facts such as Paris is in france? What is an idea? Does it come after or before sensation like seeing or hearing. 

As philosophers are wont to do it is an analysis or breakup of the notion of knowledge.

What motivated or justified a breakup? such things as mirages, dreams, optical illusions and several others. A straight stick put into water appears bent. A rope may look like a snake or you might see water where there is none.... Here is a fruit-fly seen with bare eyes

 
When we look at the eye through electron microscopy.

which is the real one? (see more of the microscopic world at http://www.iflscience.com/technology/some-spectacular-sem-images-microscopic-world/)
There are many cases where our senses fail us. We want knowledge to be beyond failures of the senses. How to go about it?

Questions of epistemology are linked to questions of what is really real or ontology. Ontology is theory as to what exists, or inquiry into the nature of being."Onto", which means existence, or being real, and "Logia", which means science, or study. Studies and organises what is real. The objects around in my room table, chair etc are they real? We want to distinguish between appearance (such as can be captured by odinary camera) and real picture as can be captured Xray diffraction or electron microscope. Which of them is real? But scientists tell us that each of them is made of atoms-(The ultimate reality ?).

 What about numbers such as 9 or 99. Plato developed this distinction between true reality and illusion, in arguing that what is real are eternal and unchanging Forms or Ideas (a precursor to universals), of which things experienced in sensation are at best merely copies, and real only in so far as they copy ('partake of') such Forms. In the Allegory of the Cave, the objects that are seen are not real, according to Plato, but literally mimic the real Forms. People in the cave only see shadows not real objects. For Plato the forms represented the ultimate reality -a  substantial reality as opposed to notional reality.


 But whereas Plato separated them into two different worlds , Aristotle instead said that the forms of things are in the things themselves and have no separate existence.Aristotle held that objects are built from matter and form. (hylomorphism).matter is formed into a substance by the form it has.The matter just is determined by the object so that particular activities and properties appear.horses, flowers, people, rocks, and so on have shapes and are subject to change but continue to be horses, flowers, people, rocks. Primary substances are subjects of predicates, single and persist through changes

Indian ideas on reality and knowledge

The Samkhya philosophy regards the Universe as consisting of two eternal realities: Purusha and Prakrti. It is therefore a strongly dualist philosophy. The Purusha is the centre of consciousness, whereas the Prakriti is the source of all material existence. The twenty-five tattva system of Samkhya concerns itself only with the tangible aspect of creation, theorizing that Prakriti is the source of the world of becoming. It is the first tattva and is seen as pure potentiality that evolves itself successively into twenty-four additional tattvas or principles. The Tattvas range from 1. Purusha (Transcendental Self) 2. The uncreated unmanifest) Prakriti (primordial nature) 3. Mahat/Buddhi (intellect) ... 21-25. The five gross elements are space or ether (akasa), water, air, fire and earth.

Pramāṇa (Sanskrit: प्रमाण, Pramāṇas) literally means "proof" and "means of knowledge".[1][2] It refers to epistemology in Indian philosophies, and is one of the key, much debated fields of study in Hinduism, Buddhism and Jainism, since ancient times. It is a theory of knowledge, and encompasses one or more reliable and valid means by which human beings gain accurate, true knowledge.The focus of Pramana is how correct knowledge can be acquired, how one knows, how one doesn't, and to what extent knowledge pertinent about someone or something can be acquired.

Ancient and medieval Indian texts identify six pramanas as correct means of accurate knowledge and to truths: perception (Sanskrit pratyakṣa), inference (anumāna), comparison and analogy(upamāna), postulation, derivation from circumstances (arthāpatti), non-perception, negative/cognitive proof 

Perhaps no other classical philosophical tradition, East or West, offers a more complex and counter-intuitive account of mind and mental phenomena than Buddhism. While Buddhists share with other Indian philosophers the view that the domain of the mental encompasses a set of interrelated faculties and processes, they do not associate mental phenomena with the activity of a substantial, independent, and enduring self or agent. Rather, Buddhist theories of mind center on the doctrine of not-self[(Pāli anatta, anātma), which postulates that human beings are reducible to the physical and psychological constituents and processes which comprise them.(anupalabdhi) and word, testimony of past or present reliable experts (Śabda). Each of these are further categorized in terms of conditionality, completeness, confidence and possibility of error, by each school of Indian philosophies.

Are the views of science and spirituality contrarians? Here's something from http://www.huffingtonpost.in/entry/science-embraces-ancient-indian-wisdom_n_6250978

Here's the short story: According to Eastern metaphysics, everything in the universe is interconnected, and consciousness pervades all matter, while the view most commonly held in Western science suggests that consciousness only occurs in humans as a byproduct of physical changes in the brain. But some research in quantum physics now supports the Eastern view that perhaps mental states do not rely exclusively on material states, and therefore consciousness may exist separately from any sort of changes occurring in the physical brain. In other words, there can be non-local connections between physical and mental phenomena -- even matter that appears to be separate may, in some way, be connected.

Descartes and Meditations

On Sense Descartes says
“Whatever I have up till now accepted as most true I have acquired either from the senses or through the senses” (7:18). 

He then went on to challenge the veridicality of the senses with the skeptical arguments of First Meditation, including arguments from previous errors, the dream argument, and the argument from a deceptive God or an evil deceiver.

In sum, in considering Descartes' answer to how we know, we can distinguish classes of knowledge that differ as regards the degree of certainty one may expect to achieve. Metaphysical first principles as known by the intellect acting alone should attain absolute certainty. Practical knowledge concerning immediate benefits and harms is known by the senses. Such knowledge is usually good enough. Objects of natural science are known by a combination of pure intellect and sensory observation: the pure intellect tells us what properties bodies can have, and we use the senses to determine which particular instances of those properties bodies do have. For submicroscopic particles, we must reason from observed effects to potential cause. In these latter cases, our measurements and our inferences may be subject to error, but we may also hope to arrive at the truth.

Descartes was examining the basis for his knowledge he therefore examined the foundations "I shall only in the first place attack those principles upon which all my former opinions rested."

He finds that he "learned either from the senses or through the senses" and these are fallible. He goes on to say "there are no certain indications by which we may clearly distinguish wakefulness from sleep that I am lost in astonishment."

"At the same time we must at least confess that the things which are represented to us
in sleep are like painted representations which can only have been formed as the counterparts of something real and true, and that in this way those general things at least, i.e. eyes, a head, hands, and a whole body, are not imaginary things, but things really existent."

"And for the same reason, although these general things, to wit, [a body], eyes, a head, hands, and such like, may be imaginary, we are bound at the same time to confess that there are at least some other objects yet more simple and more universal, which are real and true;"

"Physics, Astronomy, Medicine and all other sciences  are very dubious and uncertain; but that Arithmetic, Geometry and other sciences of that kind  contain some measure of certainty and an element of the indubitable."

"Nevertheless I have long had fixed in my mind the belief that an all-powerful God existed by whom I have been created such as I am. But how do I know that He has not brought it to pass that there is no


Descates wanted all science to be beyond doubt of any kind

" an indubitability, or inability to undermine one's conviction. Descartes' methodic emphasis on doubt, rather than on certainty, marks an epistemological innovation. This so-called ‘method of doubt’ is discussed below (Section 2)."

The certainty/indubitability of interest to Descartes is psychological in character, though not merely psychological — not simply an inexplicable feeling. It has also a distinctively epistemic character, involving a kind of rational insight. During moments of certainty, it is as if my perception is guided by “a great light in the intellect” (Med. 4, AT 7:59). This rational illumination empowers me to “see utterly clearly with my mind's eye”; my feelings of certainty are grounded — indeed, “I see a manifest contradiction” in denying the proposition of which I'm convinced. (Med. 3, AT 7:36)

"Descartes is explicitly embracing the consequence of having defined knowledge wholly in terms of unshakable conviction: he's conceding that achieving the brand of knowledge he seeks is compatible with being "

"commitment to an internalist conception of knowledge."

Ultimately, all judgments are grounded in an inspection of the mind's ideas. Philosophical inquiry is, properly understood, an investigation of ideas. The methodical strategy of the Meditations has the effect of forcing readers to adopt this mode of inquiry.

An Aside : Descartes maintains that though atheists are quite capable of impressive knowledge, including in mathematics, they are incapable of the indefeasible brand of knowledge he seeks:

Descartes insists on indefeasibility. (Typically, he reserves the term ‘scientia’ for this brand of knowledge, though he uses ‘cognitio’ and its cognates for either context.) 

The fact that an atheist can be “clearly aware [clare cognoscere] that the three angles of a triangle are equal to two right angles” is something I do not dispute. But I maintain that this awareness [cognitionem] of his is not true knowledge [scientiam], since no act of awareness [cognitio] that can be rendered doubtful seems fit to be called knowledge [scientia]. Now since we are supposing that this individual is an atheist, he cannot be certain that he is not being deceived on matters which seem to him to be very evident (as I fully explained). (Replies 2, AT 7:141)

The dialectic of the First Meditation features a confrontation between particularism and methodism, with methodism emerging the victor. For example, the meditator (while voicing empiricist sensibilities) puts forward, as candidates for the foundations of Knowledge, such prima facie obvious claims as “that I am here, sitting by the fire, wearing a winter dressing-gown, holding this piece of paper in my hands, and so on” — particular matters “about which doubt is quite impossible,” or so it would seem (AT 7:18). In response (and at each level of the dialectic), Descartes invokes his own methodical principles to show that the prima facie obviousness of such particular claims is insufficient to meet the burden of proof.

An important function of his(Descartes) methods is to help would-be Knowers redirect their attention from the confused imagery of the senses to the luminous world of the intellect's clear and distinct ideas.

Wax thought experiment

The famous wax thought experiment of the Second Meditation is supposed to illustrate (among other things) a procedure to “dig out” what is innate. The thought experiment purports to help the meditator achieve a “purely mental scrutiny,” thereby apprehending more easily the innate idea of body

Descartes now resumes the question of our knowledge of bodies. He takes as an example a piece of wax from the honeycomb. Certain things are apparent to the senses: it tastes of honey, it smells of flowers, it has a certain sensible colour, size and shape, it is hard and cold, and if struck it emits a sound. But if you put it near the fire, these qualities change, although the wax persists; therefore what appeared to the senses was not the wax itself. The wax itself is constituted by extension, flexibility, and motion, which are understood by the mind, not by the imagination. The thing that is the wax cannot itself be sensible, since it is equally involved in all the appearances of the wax to the various senses. The perception of the wax "is not a vision or touch or imagination, but an inspection of the mind." I do not see the wax, any more than I see men in the street when I see hats and coats. "I understand by the sole power of judgement, which resides in my mind, what I thought I saw with my eyes." Knowledge by the senses is confused, and shared with animals; but now I have stripped the wax of its clothes, and mentally perceive it naked. From my sensibly seeing the wax, my own existence follows with certainty, but not that of the wax. Knowledge of external things must be by the mind, not by the senses."

The central insight of foundationalism is to organize knowledge in the manner of a well-structured, architectural edifice. Such an edifice owes its structural integrity to two kinds of features: a firm foundation and a superstructure of support beams firmly anchored to the foundation. A system of justified beliefs might be organized by two analogous features: a foundation of unshakable first principles, and a superstructure of further propositions anchored to the foundation via unshakable inference.

Descartes' own designs for metaphysical Knowledge are inspired by Euclid's system:
His idea of the self does ultimately draw on innate conceptual resources.

The very next paragraph (the fourth) draws an epistemically important contrast with external sense perception (as just characterized).

This juncture of the Third Meditation (the end of the fourth paragraph) marks the beginning point of Descartes' notorious efforts to refute the Evil Genius Doubt.

For example, while reflecting on his epistemic position in regards both to himself, and to the wax, the Second Meditation meditator says:

Surely my awareness of my own self is not merely much truer and more certain than my awareness of the wax, but also much more distinct and evident. For if I judge that the wax exists from the fact that I see it, clearly this same fact entails much more evidently that I myself also exist. It is possible that what I see is not really the wax; it is possible that I do not even have eyes with which to see anything. But when I see, or think I see (I am not here distinguishing the two), it is simply not possible that I who am now thinking am not something. (Med. 2, AT 7:33)

In the concluding paragraph of the Second Meditation, Descartes writes:

I see that without any effort I have now finally got back to where I wanted. I now know that even bodies are not strictly [proprie] perceived by the senses or the faculty of imagination but by the intellect alone, and that this perception derives not from their being touched or seen but from their being understood; and in view of this I know plainly that I can achieve an easier and more evident perception of my own mind than of anything else. (Med. 2, AT 7:34)

. The theme that ideas are the only immediate objects of awareness repeats itself elsewhere in Descartes' writings. As he tells Hobbes: “I make it quite clear in several places … that I am taking the word ‘idea’ to refer to whatever is immediately perceived by the mind” (Replies 3, AT 7:181). A sine qua non of judgment error is that there be an act of judgment, but acts of judgment require both a perception and a volition. Descartes' claim that mere seemings “cannot strictly speaking be false” is therefore innocuous: for in isolating the mere seeming, he isolates the perceptual from the volitional. My merely seeming to see a speckled hen with two speckles could not, per se, involve judgment error, because it is not in itself a judgment.

The worry is that he presupposes the C&D Rule (Clarity and Distinctness) in the effort to prove the C&D Rule. There is much of interest in Descartes' arguments for an all-perfect God. (The Fifth Meditation advances a further such argument.)

Various themes about innate truths are introduced in the Fifth Meditation.


References
1. https://en.wikipedia.org/wiki/Ren%C3%A9_Descartes 
2. https://en.wikipedia.org/wiki/Pramana
3. https://plato.stanford.edu/entries/mind-indian-buddhism/
4. https://plato.stanford.edu/entries/descartes-epistemology/ 
5. https://www.britannica.com/topic/epistemology
6. http://www.philosophybasics.com/branch_epistemology.html

Descartes - Methodological Doubt

Descartes Meditation I. title "Of the things which may be brought within the sphere of the doubtful." sums up the theme of this blog. Other ways of looking at it are to ask how firm are the foundations of our knowledge ? Yet another way is to look as laying down the foundations of Rationalist epistemology. 

Rationalists believe that our knowledge comes from axioms (things that are beyond doubt) and a deductive process as opposed to Empiricists who believe that all knowledge comes from senses.

Descartes is keen to lay down firm foundations of knowledge and accordingly in first meditation lists three major problems that need to be overcome.

1. Perceptual Illusion
Our senses are sometimes prone to errors a sttraight stick inserted into water appears bent . In mirages we see water where there is none.

Descartes however believed "sensory knowledge on the whole is quite sturdy."


2. The Dream Problem
There is very little to distinguish between dreaming and waking state experience because the dreaming state appears super real. This is what our man says "At the same time I must remember that I am a man, and that consequently I am in the habit of sleeping, and in my dreams representing to myself the same things or sometimes even less probable things, than do those who are insane in their waking moments.How often has it happened to me that in the night I dreamt that I found myself in this particular place, that I was dressed and seated near the fire, whilst in reality I was lying undressed in bed!"

 Even when a painter creates an imaginary creature, like a mermaid, the composite parts are drawn from real things—women and fish, in the case of a mermaid. Descartes believed that it is important to ensure that the individual parts constituting the composite  like shape, quantity, size, time, etc.  be on firm footing. He  felt that these lay in simple things, like arithmetic and geometry.


3. A Deceiving God

Descartes  considers a radical hypothesis of "deceiving God". What if there is an omnipotent god, but that deity devotes its full attention to deceiving people?  The problem here is not merely that people might be forced by god to believe what something which is in fact false. Descartes indicates  the far more devastating possibility that whenever people believe anything, even if it has always been true up until now, a truly omnipotent deceiver could at that very moment choose to change the world so as to render their 
belief false. On this supposition, it seems possible to doubt the truth of absolutely anything you and I might come to believe.

Since God is good and kind,  Descartes supposes that not God, but some evil demon has committed itself to deceiving him so that everything he thinks he knows is false.

His solution - Doubt everything so that  one can be  sure, not to be misled into falsehood by this demon.This is the theme of this blog.

This is what he says at the start of meditation IV
"I needed to do the exact opposite—to reject as if it were absolutely •false everything regarding which I could imagine the least doubt, so as to see whether this left me with anything entirely indubitable to believe. 
Thus,
•I chose to suppose that nothing was such as our senses led us to imagine, because our senses sometimes deceive us. Also,
•I rejected as unsound all the arguments I had previously taken as demonstrative [= ‘absolutely rigorous’] proofs, because some men make mistakes in reasoning, even in the simplest questions in geometry, and commit logical fallacies; and I judged that I was as open to this as anyone else. Lastly,•I decided to pretend that everything that had ever entered my mind was no more true than the illusions of my dreams, because all the mental states we are in while awake can also occur while we sleep ·and dream·, without having any
truth in them.

The most famous quote from Descartes is  "cogito, ergo sum" ("I think, therefore I am"). It affirms  the  intuition of one's own reality, an expression of the indubitably of first-person experience and the logical self-certification of self-conscious awareness in any form.

"I am thinking, therefore I exist was so firm and sure that not even the most extravagant suppositions of the skeptics could shake it, I decided that I could accept it without scruple as the first principle of the philosophy I was seeking."

"I think, therefore I am" makes mind more certain than matter, and my mind (for me) more certain than the minds of others. There is thus, in all philosophy derived from Descartes, a tendency to subjectivity.

The cogito enables the C & D (clear and distinct) argument the indubitable propositions from which other knowledge can be deduced by proper reasoning

"For after all, whether we are awake or asleep, we ought never to let ourselves be convinced except by the evidences of our reason. Note that I say ‘our reason’, not ‘our imagination’ or ‘our senses’. Even though we •have a vividly open view of the sun, we mustn’t judge on that account that it is only as large as we see it; "

from https://en.wikipedia.org/wiki/Cartesian_doubt
Descartes' method of hyperbolic doubt included:

1. accepting only information you know to be true
2. breaking down these truths into smaller units
3. solving the simple problems first
4. making complete lists of further problems

Here are two objections from http://people.tamu.edu/~sdaniel/Notes/descar1.html

• Even to raise the possibility that our experiences might not accurately describe a world that exists apart from our experience is already to assume that the distinction of world vs. experience makes sense. But what if the things we experience are not in fact ideas at all, but are rather things in the world themselves? The method of doubt proposes that it makes sense to think of ideas or beliefs apart from how they are ideas or beliefs about a world. But apart from the assumption of an external world, it makes no sense to think of ideas as distinct from that world.
• If we doubt everything, we also must doubt whether we are truly doubting. But that gets us into an endless regress (doubting that we are really doubting that we are really doubting and so on). So the effort to reach an indubitable principle through doubt is doomed from the outset. The only way to find out that we are correct in doubting is to appeal to a public understanding of what doubt means, and that means assuming that there is a really existing world.

I summarize by quoting Bertrand Russel (History of western philosophy )

"The method of critical doubt, though Descartes himself applied it only halfheartedly, was of great philosophic importance. It is clear, as a matter of logic, that it can only yield positive results if skepticism is to stop somewhere. If there is to be both logical and empirical knowledge, there must be two kinds of stopping points: indubitable facts, and indubitable principles of inference.Descartes's indubitable facts are his own thoughts--using "thought" in the widest possible sense. "I think" is his ultimate premise."