The Principles of Philosophy and the Method of Realism | Summary of Article 3 [Knowledge and Perception]


1. The subject-matter of this article is the identification of the substance of knowledge and the soul from the perspective of it being immaterial or material – at all levels of perception (sensory, imaginative, and intellectual).

2. Perception is divided into three:

a) sensory (when senses are connected to external reality)

b) imaginative (a conception that you can perceive and also alter). The difference between sensory and imaginative:

i) Sensory knowledge is a lot clearer than imaginative

ii) The senses have to be fixated (mu‘ayyan) in some direction – the object of knowledge cannot have a barrier. Unlike imaginative knowledge, where the absence of barriers from an object is not required.

iii) Sensory knowledge cannot be attained except through one of the specific senses, whereas imaginative knowledge does not require any of the five senses.

c) rational – after you gain sensory or imaginative knowledge, you can use the intellect to extract and differentiate aspects from conceptions and ultimately derive universals.

3. The existence of all three perceptions is a mental existence and are known to us through knowledge by presence. Even Berkeley confesses that sensory perception is knowledge by presence.

4. We can study these perceptions from different perspectives – for example the perception of light can be discussed in physics, psychology, philosophy etc. The contention is whether there is any subject that can study every aspect of these perceptions and or does every subject study just a very particular aspect of it.

5. Philosophers and empiricists agree that material realities can be perceived.

6. The point of contention between philosophers and empiricists is whether there is something beyond the material world that can also be perceived.

Arguments for Immateriality of Knowledge

Evidence 1 – Indivisibility of Knowledge / A Large Object Cannot Fit into a Smaller Object

Explanation: Imagine someone took a picture of a family and behind it is very scenic with mountains and so on. When this picture comes out, we ask the question, are the contents of the picture actually in that photo? Of course not – it is not possible, the dimensions of the actual scene is much larger and cannot fit in this photo.

It is impossible for something large to fit into something small. Now imagine you go on top of a mountain and look at a scene – is it possible for that scene to be present in your mind? It is impossible since your brain is small, and the scene is too large. This is why you cannot divide this image either, it is not material, you cannot cut it. In fact, if this was the case there would be no mistake in our knowledge – it would become knowledge by presence. The fact that we make mistakes shows that the actual scene does not come to the brain.

This shows that knowledge is immaterial. This is actually a very old argument, but we will look at how the materialists responded to it.

Materialist Response: You have not analyzed the scenario correctly. When you look at the sky or a scene it gets perceived by the small pupil and the pupil transfers this image to the brain. Therefore, in essence, it is an application of a small onto a small, not large onto a small. If the material image is small in the brain, then how do we know the dimensions of the outside world then? The brain has the ability to measure the dimensions of objects in the picture and in comparison to that it can tell you what the dimensions of the outside world are – this measuring ability improves through greater induction. This is why it makes errors at times too since it may not be able to determine the correct measurements at time – like the sun.

Shahīd Muṭahharī’s Response: This measurement tool in the brain, is it material or immaterial? It did not make the picture bigger; it keeps it small. The perception of the measurements is still immaterial because if it was material it means it either makes the picture bigger or smaller, which is not what is happening. Secondly, when you make an affirmation (taṣdīq), it is a simple matter which cannot accept division – material items and their descriptions cannot be reconciled with the fact that affirmation is immaterial.

Materialist Response: Who said the picture cannot be divided? It is divided, we just don’t have any attention to it since the divisions are so small. Just like the light coming from a bulb, it is not one ray rather it is millions of smaller divided particles. This is similar to what the philosophers say for a continuous quantity (al-kamm al-muttaṣil) like a line, which is made up of dots.


1. With respect to a continuous quantity it has two groups amongst the materialists regarding what the origins of its perception are. European philosophers like Descartes say there is nothing in external reality (such as dots), rather they are simply a mental imagination (khiyāl) – the smallest thing one can perceive. Other philosophers say mathematical perceptions are based on sensory perceptions, the brain doesn’t make them up – for example when I look at the moon and sun, I see them but the mind constructs the concept of circle, likewise, it constructs the concept of lines and so on.

Both groups agree that it is not something purely material, the first group says it is from the innovations of the intellect, and the second group says senses play a role but the intellect abstracts the concepts.

2. There is no continuous quantity in extramental reality or in mental existence. This is because a continuous quantity does not accept division (inqiṣām), while what we have in the mind or in extramental reality can accept division. ‘Allāmah has essentially taken the presumptions of the Mathematicians who all believe a continuous quantity does not accept division.

3. ‘Allāmah says if a continuous quantity exists in our perceptions without any gaps and distances, let us assume as the opponents do, that it exists in the mind while it does not accept any division. Even in such a case, it does not concern us if it does not correspond with extramental reality, since at the end of the day it still exists in the mind and it does not accept division. This is sufficient.

4. Even if none of this is accepted, we will offer two instances that most definitely do not accept division. First of them is intuitions (wijdānīyāt) – such as fear, love etc. You cannot divide them, they either exist or they do not.

5. Second of them is universals – for example, a “universal human” does not accept division. If it was material, it would have accepted division and in fact, it would not have been applicable since a particular matter has individuation (tashakhkhuṣ). An external stone cannot be applied and instantiated on an external paper – this has no meaning.

If we go to the classical philosophers they would have said to ‘Allāmah we agree with you on points 4 & 5, but we do not necessarily agree with you on the first 3 points. ‘Allāmah is trying to demonstrate the immateriality of all perception absolutely as per Sadrian philosophy. If he was a Peripatetic, he would have accepted at least some types of perceptions as material such as empirical and estimated perceptions – the only difference is that there are also some perceptions that are immaterial.

We will touch upon this in later discussions, one thing to note here for your own reflection is to see if there is a difference between the existence of something and the ability to relay (ḥikāyah) something. For example, if you have a television screen it may exist in a certain dimension, but what it relays is something much larger. We will offer some observations on this in a later discussion since we feel ‘Allāmah put himself in a very restricted position with this definition of perception.

Before moving on to the second argument brought for the immateriality of knowledge, we must say that so far there is nothing new contributed within philosophical discussions, as whatever the authors have covered so far are arguments that have existed throughout the history of philosophy.

Evidence 2 – The Immutability of Knowledge

Before we explain the evidence for the immutability of knowledge and how that proves the immateriality of knowledge, we have to mention a preliminary. Philosophers say our mind goes through four stages when it comes to processing knowledge:

1) An initial empirical contact with the world which impacts the mind.

2) The mind stores this contact in its memory – regardless of whether we are able to remember or recall it later on in the future or not. This stage has nothing to do with the external world, unlike the first stage.

3) The mind remembers and recalls that concept which it had stored and collected earlier, in stage one and two.

4) In the last stage you identify and affirm that even if you keep recalling this concept multiple times over the years, humans acknowledge that this is the same concept that was recalled in the previous instances, and that it is the same concept that was first stored when empirical contact took place.

The second stage of memory is what is crucial. Over here there are multiple theories, we will mention four of them, two that have existed from the past, and two relatively recent ones:

1) Some ancient Greek philosophers would say that once we look at a painting in front of us with our eyes, it is similar to our mind scanning the object and essentially photocopying it. The author says this is a very problematic view and has been critiqued heavily.

2) Descartes’ view implies that the painting would be observed by the eye after which the eye sends the image to the brain as a very tiny particle. Since the soul merely encompasses the body, the nature of recalling from memory is simply the soul observing the material body and pieces of knowledge.

3) Mullā Ṣadrā and both our authors believe that the first stage is merely a preliminary for perception, not perception itself. When we encounter an object, the mind creates the image, identical to the object without being impressed by it. The mental image is not by impression by the external object, rather it is an origination (ṣudūr) by the soul. In this case, memory is simply the storage of this mental image in the mind – not the brain – and the mind is abstract. This mental concept always exists in the mind, like a piece of furniture in a house, but we can forget about it as we lose attention and focus on it, whereas in the process of recollection we are simply choosing to focus on it. With this explanation, forgetfulness is simply the loss of focus and attention towards the mental image which already exists in the mind, not that the mental image itself ceases to exist.

4) A group of contemporary philosophers – especially proponents of Dialectical Materialism – believe the senses are constantly perceiving different things and at any given moment when the senses are focused on an object that is when one has knowledge. As soon as the sense perception cuts off from that object the knowledge ceases to exist altogether. This perception creates and leaves a physical impression on the brain and when it comes to memory, it does not recall the exact same perception that it had when the senses were in physical contact with the object, rather due to the impressions created on the body, it deduces a new perception of what it had experienced in the past. This perception resembles the initial perception and is not exactly the same.

Critique of the Second and Fourth Materialist Theory of Knowledge

1. If knowledge is material as implied by the second and fourth theory, the body and brain simply would not be able to handle it. This is because the quantity and amount of knowledge humans perceive and gain during their lives is immense.

2. In the fourth stage where you are meant to identify and affirm that the concept is the same, we know through knowledge by presence that the recollection of my perception is the exact same as the initial perception, not that it is a brand new perception. Proponents of the second and fourth theories have not been able to address and respond to this – where is this feeling and acknowledgement of unity between the two perceptions coming from?

3. The human body goes through physical change multiple times during its life, and the physical Zayd at age 5 is not the same physical Zayd at age 50. The cells of the bodies have all changed, then how is it possible to still have knowledge of the past if physically the body has changed?

Response by Materialists and a Counter-Response

The materialists can argue that we know today that the brain has different parts that engage in different processes. One of these parts of the brain takes care of the memory and we can explain the phenomenon of forgetfulness easily. When a person is hit on the head or experiences physical trauma of some sort, we see that it can result in loss of memory. This is similar to any other physical object, if it is damaged, a part of it can stop working. However, how do the immaterialists – from the third aforementioned camp – explain the phenomenon of forgetfulness when they claim that knowledge and perception are known by presence? If it is known by presence, forgetfulness has no meaning.

The Sadrian philosophers will respond by saying, we believe the soul is immaterial in its essence, but we do not deny it is connected to the body in this world and that it requires the body to do certain acts. Hence in this world, even though knowledge and perception are present with the soul, in order to recall a certain perception in this world, it requires the brain and if the brain is injured it is unable to do so as it is not able to focus on a certain perception it is trying to recall.

In conclusion, the second evidence for the immateriality of knowledge can be summarized as follows:

1) We are able to recall certain perceptions from the past, and during this recollection of our memories, we understand that the perception which is being recalled is the exact same as the initial perception.

2) If this was not the case, there would be no such thing as “recollection”, as one is not recollecting or recalling anything, rather it is a new and different perception.

3) The whole human body changes during its life, and if knowledge were material, one would not be able to recall things from the past as they would no longer exist as one grows up.

Another Response by Materialists and a Counter-Response

Some of the materialists have tried to answer another critique which says that if knowledge is material, certain perceptions would not exist, such as universal perceptions, because matter is always particular. They respond to that as follows:

1) We have proven in our philosophical discussions that the relationship between objects is a two-way relationship, meaning if A impacts B, A will itself also be impacted by that relationship. It is not the case that A will impact B and nothing will happen to A.

2) The body interacts with the world; both the world and the human body are impacted. This relationship and impact are purely material.

3) What remains in the mind is a material perception and it remains with the body.

4) This new entity that is created in the mind, it also interacts with the brain and the same process occurs again where both the entities impact one another. Since this process is occurring continuously, that is what makes us perceive “universals”.

The author refutes this argument as follow:

1) We do not disagree with the physical description of how knowledge is gained due to our interaction with the outside world. This is because, for us (Sadrian philosophers), it is irrelevant how this physical process occurs. However, despite that we have a question regardless: if this knowledge is material, why does not have the qualities of matter (as discussed in the first evidence regarding the impossibility of putting a large object in a smaller object, and matter having the capacity to be divisible).

2) Even if we agree with the premise that when objects in this world interact, they both leave an impact on one another, but why is it that when it comes to the specific relationship of humans with the world, we find something extra occurring in this relationship and that is the notion of uncovering (kashifīyyah) of knowledge. How come we do not find this notion in the relationship of other objects amongst one another, why does it only exist in the case of knowledge? If you reject this notion of uncovering, then in this case you will fall back into the camp of the Idealists, as you will have to acknowledge that the knowledge in your mind does not convey anything about external reality.

A Third Response by Materialists and a Counter-Response

Some materialists have argued by saying that knowledge and perception is not detached from the attribute of time, and all that occurs within time is material.

The author responds by resorting to a different fundamental premise which is based on Sadrian philosophy. He says, matter is always accompanies the qualities of matter, which includes time and change. If knowledge is indeed material, then it must also be changeable, and this has already been rejected earlier. As for time, it is just the quantitative amount of motion (miqdār al-ḥarakah) as per Sadrian philosophy – there is no time without motion, and there is no motion without matter. This means that knowledge is not attributed with time.

One should not confuse this argument by thinking knowledge is definitely attributed to time because at one point you are ignorant, at a second point you know something new. What is time-based are the preliminaries of perception and knowledge, not knowledge itself.

Evidence 3 – The Immateriality of the Soul

A final argument for the immateriality of knowledge is by proving the immateriality of the soul itself. There are two groups of philosophers in this field, a group who do not believe in the existence of a soul at all, and those who believe in the existence of a soul. The latter group believes the soul is independent and is different than the material body.

The Muslims have offered dozens of arguments for the existence and immateriality of the soul, some are strong, and some are weak, but the author does not go into all of those extensive arguments.  ‘Allāmah and Shahīd Muṭahharī essentially rely on the argument of Ibn Sīna, but with a slightly different presentation of it.

We all have knowledge by presence of our own existence. This is agreed upon by all Muslims, even if they disagree on the nature of knowledge by presence, or if they disagree with the definition of knowledge by presence offered by the Illuminationists and Sadrians, or they may disagree on the instances for which we have such knowledge. The famous instances are:

a) knowledge of the self and its states – all agree on this,

b) knowledge of the cause towards its effect,

c) knowledge of an effect towards its real cause (the Peripatetics rejected this),

d) knowledge of an effect towards another effect (this is accepted by the mystics, even though the philosophers have found it difficult to prove it).

Shahīd Muṭahharī’s presentation of the evidence is as follows:

1) I perceive my own existence, life, and my thoughts with knowledge by presence. When I say, “I think”, or “I see”, I also realize that there is a difference between myself and my thoughts and perceptions. My self is independent to my thoughts, but my thoughts are dependent on my existence.

2) I perceive my own existence both in the past and now, but I do not find any change in this very simple knowledge by presence with regards to my very existence. Rather, what I find different is that there is an increase in my knowledge or an increase in my experience. We do not say, I existed, but today my existence has partially diminished.

3) All the arguments that were made to prove the immateriality of our memory are presented here. If our memories are immaterial, then the place where these memories are stored is also immaterial.

4) This is while our physical body changes throughout its life multiple times, completely. It completely changes, yet we do not find any change or difference in the fact that I exist – that existence remains the same, we perceive unity in it, and it does not change. In this case, we apply the same evidence as we used on the immutability of knowledge and apply it to the soul, which shows that the soul is not material, it is an independent entity.

‘Allāmah’s presentation of the evidence is as follows:

1) We have knowledge by presence towards our existence.

2) We have knowledge that our existence is different than our limbs, body, thoughts, etc. because we attribute them to ourselves, as “my” body, “my” limbs, or “my” thoughts.

3) We have knowledge that our existence does not change as we grow up from being a child to an adult to an elderly, while our body goes through changes, from being weak, strong and weak again. This shows our existence is something different than our bodies.

4) Our existence does not change with the loss or growth of a limb. The fact that we can lose multiple limbs, yet still believe we exist without perceiving a change in our very existence, this shows that our existence is something different and independent.

5) We have knowledge by presence that this existence is the same in the past and in the present, and our knowledge from memory assists us in affirming this.

6) We have knowledge by presence that our existence is indivisible.

7) When we concentrate on the knowledge by presence of our very existence, we realize that it has no limits. Unlike when we consider the knowledge of our bodies, where we can tell there is a limit, we can fit through a certain space or not, we can walk at a certain speed or not. However, when we focus just on our existence, we do not have any conception of any material limitation.

8) From all of these admonitions, we realize that our self is immaterial and independent and that the knower and the known object is one.