Part 4 - Descartes

Descartes has been regarded as the “father” of modern philosophy.  He was born in France in 1596. He received a very good education at a Jesuit College, but he also had an unusual independence of mind, and while still a student he perceived that the various authorities he was studying often put forward arguments that were invalid. As a young man he became a soldier, and traveled widely in Europe, though without  seeing any fight. He became fascinated by the question whether there was any way at all in which we human beings could get to know anything for certain, and if so how.  He stopped travelling , and went into seclusion in Holland, the country in which intellectual life in those days was at its freest. And there, he produced work of the profoundest originality in mathematics and philosophy and also did a great deal of work in science.

He invented the branch of mathematics known as co-ordinate geometry, so every time we look at a graph with its Cartesian axes we are looking at something invented by Descartes. His most famous works in philosophy are Discourse on the Method, and Meditations, published in 1642. Descartes never married, though he had an illegitimate daughter who died at the age of five: her death was the greatest emotional blow of his life. After repeated invitations, he finally agreed to go to Sweden to give private tuitions in philosophy to Queen Christina. It was a deadly mistake. In the bitter Swedish winter he succumbed to pneumonia, and he died in 1650.

Meditation I

Descartes was impressed with the universal acceptance of Mathematics and Geometry, why, on the contrary, were there so many debates and disagreements in philosophy? Is not philosophy meant to be a rational, logical science? He noticed that mathematics and geometry started with few, very clear and distinct truths or axioms; these truths are known immediately and clearly by means of INTUITION. From these clear truths by means of DEDUCTION we then build up step by step a solid and precise body of mathematical and geometrical knowledge, which enjoys universal agreement. Can the same process be applied in philosophy? Can we begin to discover by intuition a few, or even one completely clear and distinct truth?

Descartes decides to search for the unassailable truth, resistant to all possible attacks; like Archimedes, he searches for a “point which was fixed and assured”, an indubitable truth on which to base his philosophy. How to achieve this? Descartes decided to use the “methodical doubt”: assess carefully all received knowledge to see how valid and certain it was, reject the kind of knowledge that was open to any doubt: empty the basket (your mind) of apples (your pieces of knowledge) and put back only those that are good! Clearly one cannot assess each individual piece of knowledge, hence knowledge is divided into classes and a class is rejected if elements of that class appear open to doubt.

“Several years have now elapsed since I first became aware that I had accepted, even from my youth, many false opinions for true, and that consequently what I afterwards based on such principles was highly doubtful; and from that time I was convinced of the necessity of undertaking once in my life to rid myself of all the opinions I had adopted, and of commencing anew the work of building from the foundation, if I desired to establish a firm and lasting superstructure in the sciences.”

Descartes divides the knowledge he thinks he has at the moment into two major categories, knowledge acquired through the senses, and knowledge “a priori” (that is, independent of the senses), and assesses each of the two categories asking himself the question: “How solid is this knowledge? Is this knowledge indubitable?”.

  • Knowledge acquired through the senses: 
    • of things far away or minute: this knowledge is not at all solid because often we are deceived (the sun to the senses looks small, small animals in the distance can be easily mistaken, etc.); this knowledge cannot provide the firm foundation needed.
    • Of things close to us, like “that I am here, sitting by the fire, wearing a dressing gown, with this paper… how could I deny that these hands and this body belong to me…”: most people would readily agree that we have here solid knowledge, but not Descartes. He argues that when he dreams all kinds of objects, animals, bodies appear very real, and yet we know that they are not, they are simply images in a dream. How do I know that I am not dreaming at this moment? How do I know that my body is not simply an image in a dream in God’s mind or in my own mind?
    • Contents of dreams: colours, shapes, sounds, etc may indicate that they belong to real objects, on the other hand all contents of dreams may simply be creations of my own mind. Such knowledge is not certain.
  • A Priori knowledge:
    • So far Descartes has found no truth which is indubitable; but he thinks that knowledge which is not based on the senses may be much more solid. And so he progresses in his assessment of such a priori knowledge. For example, how solid is my knowledge that a triangle has three sides? That 3+2=5? That if yesterday was Monday then today is Tuesday? Have we not found here the type of unassailable truth Descartes is looking for? To answer yes is very tempting, but can this knowledge resist any attack? Is it really indubitable?
    • But, who can assure me that God has not created me in such a way that I am always deceived in these things?  How do I know whether my mental faculties are up to the task of seeing the truth (whether mathematical or logical)? God clearly allows me to be deceived on occasions; why should He not let me be deceived all the time? And, perhaps, God does not exist at all and this explains why I am so often deceived; perhaps my constant deception may originate not from God but from “some evil demon, no less cunning and deceiving than powerful, who has used all his artifice to deceive me”: this is what Descartes calls the “malin genie”!


At this stage Descartes is a most radical sceptic: not only is knowledge of any kind doubtful, but even his mental faculties are doubted! We have no means whatsoever of reaching any truth, we are perennially deceived! Our same logic may be faulty, it may appear “logical” and truthful to us but, from the outside the human race, it would be possible to see how continuously mistaken we actually are. For David Hume, a most radical sceptic, Descartes’ doubt  at this stage is “entirely incurable”: if the means of discovering the truth are in doubt how can one make a single step forward? Descartes is condemned to radical scepticism.

Meditation II

“The Meditation of yesterday has filled my mind with so many doubts, that it is no longer in my power to forget them. Nor do I see, meanwhile, any principle on which they can be resolved… I suppose, accordingly, that all the things which I see are false; I believe that none of those objects which my fallacious memory represents ever existed; I suppose that I possess no senses; I believe that body, figure, extension, motion, and place are mere fictions of my mind. What is there, then, that can be esteemed true?”

Descartes’ world of knowledge lies in ruins: is there anything left? Apparently not, until one realises that my doubting, my thinking is absolutely necessary in order to be deceived: “Myself, at least, am I not something? But I have already denied that I have any senses or any body… I had persuaded myself that there was nothing at all in the world… Was I not therefore also persuaded that I did not exist? No indeed: I existed without doubt by the fact that I was persuaded… I am, I exist is necessarily true, every time I express it or conceive of it in my mind”: Cogito ergo sum, I think therefore I am. This is indeed the unshakeable truth Descartes was looking for: even the remote possibility of a malin genie cannot render it doubtful, since in order to be deceived one has to exist. St. Augustine had already discovered such truth when he wrote “Si fallor, sum” (If I am mistaken, I exist).

“I assuredly existed, since I was persuaded. But there is I know not what being, who is possessed at once of the highest power and the deepest cunning, who is constantly employing all his ingenuity in deceiving me. Doubtless, then, I exist, since I am deceived; and let him deceive me as he may, he can never bring it about that I am nothing, so long as I shall be conscious that I am something. So that it must, in fine, be maintained, all things being maturely and carefully considered, that this proposition “I am, I exist”, is necessarily true each time it is expressed by me, or conceived in my mind”.

At this stage for Descartes the Cogito, Sum is true only when it is clearly seen by the mind, since he had already stated that he cannot rely on his “deceptive memory”. This truth, therefore, is truth whilst it is contemplated by the mind. The problem for Descartes is now to establish a way to get out from this contemplation in order to discover other truths, since each time he attempts to do so he must use his “deceptive memory” (deceptive because under the possible influence of the malin genie) This problem is dealt with in Meditation III: we shall then see that God will be the only way of overcoming this “solipsistic” position, at the cost, perhaps, of presenting a circular argument!

The only truth achieved by Descartes so far is that he exists while he is thinking; an immensely important truth, an existential truth; the unshakeable awareness of his own existence at the moment he thinks is his starting point to philosophy. According to Sartre, there cannot be any other starting point: you need to know for certain that you exist before you can start building up your system of truth, if there is any other truth. The cost has been immense: Descartes, at this stage, knows for sure that he exists as a thinking being: he does not know whether he has a body, he does not know whether other people exist, he does not know whether the stars, the earth, the trees, all material things exist, and moreover he does not know whether God exist.

Descartes has arrived at his first existential truth, the certainty that he exists as a thinking being: his next effort in Med. II is to clarify this concept. What am I? He must take the utmost care not to introduce any element which he has not proven. What did he think he was before he discovered the Cogito? He thought he was a “rational animal”: but clearly he cannot accept this definition at this stage since he now possesses only one truth, the Cogito, Sum. He does not know what “animal” is, nor can he reason about what “rationality” is, since the possible existence of the malin genie would render doubtful all his arguments. He thought he had a body: but this also cannot be accepted at this stage because of the dream hypothesis and the malin genie. He assesses the attributes of the “soul”: eating, walking, sensing, perceiving: but these attributes seem to imply the existence of the body hence cannot be accepted.
So what can I say I am? A thinking thing: “That is to say, a thing that doubts, perceives, affirms, denies, wills, does not will, that imagines also, and which feels”. This is what it means to say that I am a thinking thing: it may well be that nothing else exists, but these thoughts in my mind most certainly exist: even if there are no corresponding real objects anywhere, the thoughts themselves exist in my mind.

But, are we not in the habit of thinking that “real objects”, if they exist, are known by means of the senses and of imagination rather than by the MIND, the understanding alone? Yes, but we are indeed mistaken: “real objects”, if they exist, are known by the MIND alone! And this means that we are mistaken also to think that material objects are more easily known than the human mind, since in our knowledge of material objects it is the MIND that does the knowing, it is the MIND that “judges” and acknowledges material things. The “wax experiment” is intended to prove this.

“Take, for example, this piece of wax; it is quite fresh, having been but recently taken from the beehive; it has not yet lost the sweetness of the honey it contained; it still retains somewhat of the odour of the flowers from which it was gathered; its colour, figure, size, are apparent to the sight; it is hard, cold, easily handled; it sounds when struck upon with the finger. In fine, all that contributes to make a body as distinctly known as possible, is found in the one before us. But, while I am speaking, let it be placed near the fire: what remained of the taste exhales, the smell evaporates, the colour changes, its figure is destroyed, its size increases, it becomes liquid, it grows hot, it can hardly be handled, and, although struck upon, it emits no sound. Does the same wax still remain after this change? It must be admitted that it does remain; no one doubts it, or judges otherwise. What then was it I knew with so much distinctness in the piece of wax? Assuredly, it could be nothing of all that I observed by means of the senses, since all the things that fell under taste, smell, sight, touch, and hearing are changed, and yet the same wax remains”.

What makes you know this particular piece of wax? One is tempted to answer that we know the wax through our “senses” and “imagination”. The senses provide us with the “secondary qualities” which make up the wax: the sight tells us that this wax is white, etc. and so the other senses; but if you put the wax near the flame, all the “secondary qualities” (colour, taste, smell, sound, texture) change, therefore you have a completely different set of qualities and yet you still “know” that the wax is the same wax: clearly the senses cannot achieve this knowledge, hence it is only the MIND that “judges” that beyond the different set of qualities there is the same wax. So the MIND knows the wax: animals do not “know” the wax although they can experience the wax with their senses! Human mind does the knowing, hence human mind is most readily known by us, much more than anything outside itself.  Descartes gives another example;

“Observe human beings passing on in the street below, from a window. In this case I do not fail to say that I see the men themselves, just as I say that I see the wax; and yet what do I see from the window beyond hats and cloaks that might cover artificial machines, whose motions might be determined by springs? But I judge that there are human beings and thus I comprehend by the faculty of judgment alone which is the mind, what I believed I saw with my eyes”.

You have noticed that Descartes has introduced here an important theory on the way we humans perceive material things, a theory which was also accepted by Locke, by Kant, by Russell. If you take any object, all that you receive through your senses are called “secondary qualities”: colour, taste, smell, sound, texture. But there must be something else in the object which keeps together the secondary qualities: the colour is the colour of something, the smell is the smell of something, etc. Also, there are infinite variations in the way each human being perceives the secondary qualities of any object: the red you see in this Barolo is slightly different for any human being looking at it, so which red is the real red? How can I say to “know” the red of my Barolo if this red is different from everyone else looking at it? The theory suggests that beyond the “secondary qualities” of any object there are “primary qualities”, beyond the “accidents” – to use a Scholastic term – there is the “substance” (for Kant, beyond the phenomena there are the noumena, for Russell, beyond the sense-data there are the physical objects: both agree that we do not have knowledge of the noumena or of the physical objects; we can only talk of the phenomena or sense-data).

The distinction between accidents and substance is of great importance for our understanding of “transubstantiation”: the accidents of bread and wine remain unchanged, but the substance has changed: after the Consecration we no longer have the substance of bread or wine but the substance of the Body and Blood of JESUS – yet the accidents are the same.

For Descartes, the “primary qualities” of any object are “extension, flexibility, movability”: these primary qualities can be inspected by the mind alone, whereas the secondary qualities are given by the senses. The mind goes beyond the secondary qualities to know what is permanent in any object, that is its extension, its occupying some space. We shall return to this fundamental theory in Meditation VI.

Meditations III-IV-V

Descartes has so far reached the one unassailable truth of the Cogito, ergo sum. He does not know anything else. He may well be in danger of being unable to discover any other truth whatsoever, with the consequence that he is only Mind with many thoughts, completely alone, with no body, no other people, no universe: this view is called “solipsism”, the view that I am “solus”, alone, incapable of proving the existence of any other thing. The problem for Descartes is very acute, since he has introduced the malin genie, the possibility that our mental faculties are unable to discover any truth, that our logic, our reasoning may be faulty. The only way out for Descartes is to prove that the malin genie does not exist, to prove that our logic is indeed valid, that we can discover other truths with absolute confidence.

How can he then proceed? He must prove that God exists, since if the almighty, all loving God does exist, then obviously the malin genie that deceives me at every step cannot exist. Descartes needs God to move out of his solipsism.

“But, that I may be wholly able to remove my doubts, I must inquire whether there is a God, as soon as an opportunity of doing so shall present itself; and if I find that there is a God, I must examine likewise whether He can be a deceiver; for, without the knowledge of these two truths, I do not see that I can ever be certain of anything”.

Descartes has discovered the bed-rock of truth, the Cogito: he notices that the characteristic of the Cogito is that it manifests itself as a “clear and distinct idea”, and therefore he makes it into a general rule that all “clear and distinct ideas” are as true as the Cogito. But is there any other clear and distinct idea a part from the Cogito? We will know the answer only after we can defeat the malin genie, and to get rid of the malin genie we must provide a proof of the existence of God. God, therefore, will be the guarantor that all clear and distinct ideas are true. But how to prove the existence of God? This is a real problem for Descartes, at this stage: he cannot rely on his possibly faulty reasoning, if his logic is incapable of truth how is he going to use logic to discover the truth that God exists? Descartes provides us with two arguments for the existence of God.

First argument for the existence of God:
He, Descartes, had a clear and distinct  idea of something more perfect than himself. Indeed he had a clear and distinct idea of a fully perfect Being, namely God. Now Descartes followed the current philosophical view that it was logically impossible for a cause to contain or to be less than any effect that it produced. Imperfection was less than perfection; therefore, since Descartes could clearly and distinctly conceive of a supremely perfect Being and, since he knew that he was not himself supremely perfect, it must follow that a supremely perfect Being had caused Descartes to have the conception. If you walk by the seaside and notice a small print in the sand you know that something as small as the print has left the mark; equally a huge print requires a huge being. Since we have the idea of a perfect, almighty. eternal, all loving Being, and since neither ourselves nor our parents nor anyone else in this world is that perfect Being, there must be a perfect, almighty, eternal, all loving Being that has caused that idea in us. Therefore God exists.
Second argument for the existence of God:
If we take any idea we have now in our mind and analyse it we observe that the essence of that idea is independent of ourselves and tells us the fundamental truths contained in the idea. Take the idea “triangle”: its essence is the truth of a geometrical figure formed by three sides, and a variety of truths contained in the essence – it has three internal angles the sum of which is always 180, and all other truths – and all these essential truths are true independently of ourselves. If we take the idea “God” then we see that its essence is of the existing perfect Being, endowed with all possible perfections. All the truths contained in its essence are independent of us; existence is a perfection, therefore it is contained in the essence of God, therefore God exists. This reasoning attributing existence to an idea in our mind is valid only for God because only the idea God contains as part of its essence the perfection of existence. The idea triangle does not contain existence as an essential attribute, nor does the idea of anything else. Descartes could say that “God exists” is an analytical statement, or even a tautological statement: the idea God already contains the fact of God existing, it is like saying, “He who exists exists”, “the Being that has existence as essential to Himself exists”. This argument has been called the Ontological argument, the argument that proves God’s existence by simply analysing the meaning of the idea God.

This argument was proposed in the first instance by St. Anselm in the Proslogion. He argued, against the “foolish man” of Psalm 14 (The foolish man says in his heart, “There is no God”) that in order to deny God the foolish man must know what God means. Anselm suggests that all humans have the idea of God as the greatest possible conceivable Being; if God is by definition the greatest possible conceivable Being then He cannot lack existence otherwise He would not be the greatest possible conceivable Being, being existence such a fundamental perfection or attribute. How can the possessor of all possible perfections lack such a fundamental perfection like existence? Therefore God exists. Anselm is well aware that such reasoning applies only to God, whose essence is existence, whose essential quality is “aseity” (all other things are “contingent”, they do not contain existence as part of their definition; perfect islands, or perfect horses may or may not exist, since existence is not contained in the definition of an island or of a horse). 

Descartes has now provided us with two proofs of God’s existence, therefore he can now proceed in building up his philosophy. He knows that given God’s existence and given His perfections we can rely fully on our ability to discover the truth, we can rely on our mental faculties, on our logic, on our rationality. Our intellect can discover the truth. There is therefore no malin genie that continuously perverts our logical reasoning. We can now use our rationality with confidence and know that all “clear and distinct ideas” seen by our mind are absolutely true, like the Cogito. This guarantee only covers “clear and distinct ideas”, therefore a true philosophy must progress by means of clear and distinct ideas.

It is clear that the existence of God is of fundamental importance for Descartes’ philosophy; without God Descartes would be stuck permanently with the one truth of the Cogito, unable to move one step further. His critics therefore have concentrated on attacking his proofs for God’s existence. The very first criticism is that Descartes is involved here in a circular argument, an invalid argument which is therefore false. He wants to prove that all clear and distinct ideas are true; to do so he must prove that God exists; he starts with the clear and distinct idea we have of God to prove that God exists; God exists, therefore all clear and distinct ideas are guaranteed to be true. This is a circular argument, therefore it cannot be accepted.

Hume claims that by introducing the malin genie Descartes has put himself in an impossible situation, “his doubt is incurable”: if our mental faculties are faulty then we got nothing else to prove that they are not faulty; Descartes cannot use his possibly faulty reason to prove that our reason is not faulty. He simply cannot move on, he becomes, against his own intentions, a most radical sceptic, we are barred from truth.
The Jesuit philosopher Fr. Coplestone tries to save Descartes by pointing out that Descartes is not actually making use of reasoning in order to arrive at the proof that God exists. He believes that the Cogito ergo Sum contain in effect two immediate, intuitive truths: that I exist while I am thinking, and that God exists as the background of my own limited existence. In other words, both the I and God are given immediately, without using reason, the moment we catch ourselves thinking and existing at the same time. God is the necessary background explaining our finite, limited, perception of our own existence.

For Sartre, on the contrary, Descartes has indeed discovered the primordial truth of the immediate awareness of our existence, but the way out, for Sartre, is not God. Descartes’ mistake is his failure to realise that the I does not exist in isolation, that the I implies the Thou, the other. We perceive ourselves in the presence of the others. The I and the others are given contemporaneously, we do not need to prove that the others exist, we perceive ourselves existing among all others. You would not be able to say I unless you are in the presence of others or of objects; by saying I you are affirming, distinguishing yourself from other people and from trees and horses. Heidegger also claims that other people and the world are given immediately as we become aware of ourselves, there is no need to prove that other people and the world exist. For Martin Buber, the I cannot be pronounced in isolation: it is always either I-Thou or I-It, the I is a relational word, always implies the other: we are essentially related, to others and to the world.

The ontological argument was rejected by St. Thomas Aquinas, by Hume, by Kant, and by Rosmini, for a variety of reasons. The fundamental mistake is said to be the confusion between the world of ideas and the world of reality, between ideal being and real being. The world of ideas simply proclaims the possibility all things, including God; the passage to the world of reality must be caused either by direct experience or by a necessary connection discovered by the mind. St. Thomas Aquinas’s Five Ways of proving God’s existence start from facts: the fact that the universe exists (what caused it into being? There must be an Uncaused Cause); the fact that the universe is beautifully ordered and governed by the most intelligent laws (there is design, there must be an intelligent Designer); from the fact of morality, etc.

Meditation VI

This is the last Meditation, and the reader may well be surprised to notice that so far Descartes has managed to prove his own existence as a spiritual Mind, the existence of God, and the truth of all clear and distinct ideas (logic, mathematics, geometry enter into this category). He does not know yet whether he has a body, nor whether there are other people, nor whether there is a physical world. Meditation VI attempts to provide certainty for the existence of one’s own body, of others, of physical objects.

To achieve this Descartes uses what has been called the “causal theory of perception” and the “representative theory of knowledge”. Descartes is, at the moment, a pure mind: yet his mind is forced to think many ideas of things which he does not even want to think about. He is thinking now of trees, birds and grass, but he would rather think of triangles. What forces him to think of things he does not want to think about? Perhaps God forces ideas in Descartes’ mind: this cannot be possible because Descartes now knows that there is God and God is no deceiver. Perhaps Descartes himself creates such ideas: this again cannot be possible since Descartes does not even want to think of such ideas. The only possible solution is that Descartes is thinking of trees, birds, and grass simply because his senses provide his mind with representations of real, physical objects outside Descartes, real trees, real birds, real grass.

These real objects are the cause of his having representations or ideas in his mind, and therefore real objects exist: he does have a real body, other people do exist, and all other physical objects exist. He does realise, however, that this proof relies heavily on the senses, which he had declared untrustworthy. Therefore he is forced yet again to call on God: the senses are indeed unreliable but God has put in us powerful instinctive beliefs about the existence of bodies and God would not be God if He were to allow that we should be deceived in such fundamental things. God, however, only guarantees the clear and distinct ideas contained in our perception of things, He does not guarantee the independent existence of secondary qualities.

The final part of this chapter contains Descartes’ Theodicy: very short and very weak. But there is another issue in this chapter which has had great influence and which has been discussed, accepted or criticised ever since: the relation between the mind and the body. For Descartes the essential man is mind; his body is not essential to him. Whether I got a body or not, I am totally myself when I perceive myself as a thinking being. Indeed, when my body dies, I am still myself. Given this view of two separate substances, the thinking substance and the bodily substance, how do the two substances interact? This is the famous Cartesian Dualism. We are made up of two opposite things: the mind (spiritual, indivisible, un-extended, immortal, thinking) and the body (material, divisible, extended, mortal, un-thinking): how can these two opposite substances go together in any individual? Descartes’ solution was to say that mind and body “interact” in a most intimate manner, communicating with one another through the pineal gland in the brain. The body sends messages to the mind and the mind to the body and the two interact continuously: the mind is not like “a pilot in a ship”: on the contrary, if the body is hurt the mind feels pain, if the stomach is empty the mind feels hunger, etc. There is a most profound interaction between mind and body.

However, the problem is there: how can two opposite substances work together? How can a spiritual substance cause motions in a material substance? In science we know that matter moves matter, we have no instance of spirit moving matter, of minds causing physical events and vice-versa. The issue is of immense importance today: Cartesian dualism is heavily criticised, even ridiculed – G. Ryle called it “the ghost in the machine theory”. Today’s trend in the philosophy of mind is to declare the mind part of the physical world, a physical object, the brain, or to deny that there is a mind at all.

Rosmini appreciated many of Descartes’ conclusions, especially his certainty that human intellect is made for the discovery of the truth, and his strong defence of the irreducibility of the mind to physical matter. But he advanced also a number of criticisms. He thought that Descartes had been arrogant to discard the accumulated wisdom of many philosophers before him, intending to start philosophy anew, as though no one before him had discovered any worthwhile truth. He argues that Descartes should not have started with a methodical “doubt” but rather with a methodical “ignorance”, since doubt implies having experienced the truth, the same way as dreaming implies having experienced the state of being awake. The all embracing methodical doubt is simply not possible because it disregards the cases when the senses are actually veridical. Moreover, the famous Cogito is also criticised.

For Rosmini, it is not true to say that the first truth is the perception of oneself thinking and therefore existing. Descartes has not proven the existence of the I, of the subject of thinking, he simply assumed that the thinking is being done by the I, without explanation. Russell also criticises Descartes on this point, saying that the most Descartes is entitled to say is, “There is thinking going on”, he cannot say that it is the I that is doing the thinking without previous explanations. So the Cogito cannot be the first truth; at most it is a reflection of the I on its own activity, therefore it comes after the intellective perception of oneself, which requires both the idea of being shining before the mind and the fundamental feeling of one’s body.

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