Chapter Five: Necessity, Impossibility, and Possibility
In this chapter terms such as ‘necessity’, ‘impossibility’, ‘necessity by essence’, ‘impossibility by essence’, ‘possibility by essence’, ‘necessity by others’, and ‘impossibility by others’ are introduced.
Therefore, we start our discussion by giving a brief and indefinable concept in philosophy, and then we will try to explain these terms in the light of the two self-evident concepts of existence and non-existence.
Necessity
If we consider such items as ‘flower’, ‘even’, ‘white’, ‘sweet’, and ‘eight’, we will see that among these items only ‘even’ can be related to ‘eight’, and ‘white’ to ‘flower’, and these relationships are reflected in the mind of man in the two statements of ‘eight is even’ and ‘flower is white’. No doubt because ‘even’, ‘sweet’ or ‘eight’ have nothing in common with ‘flower’, or ‘flower’, ‘white’, or ‘eight’, or finally ‘white’, ‘sweet’, and ‘even’ with each other, there can exist no statement in our mind describing their relationship, such as ‘eight is sweet’ and so on. In other words, the statement ‘eight is an even number’ expresses the relationship between the attribute ‘even’ and the number eight and the statement ‘the flower is white’ indicates the relationship between the attribute ‘white’ and the flower.
Now we turn our attention to the two mentioned relationships. It is clear that the attribute ‘even’ and the number eight, unlike the attribute ‘white’ and the flower are inseparable related to each other. We cannot imagine any number eight that is not even. However, we can imagine a flower that is not white, or even imagine certain states and conditions where the white flower loses its whiteness and acquires another colour. In philosophical terms it is said that the relationship between ‘white’ and ‘flower’ is unnecessary. We can also put the necessity or non-necessity of this relationship in a statement, and say, for example, “Eight is necessarily even,” and “Flower is white but unnecessarily.” In these two statements, besides showing the relationship, we have identified its kind. In technical terms, words such as ‘necessity’ or ‘non-necessity’, which show the kind of relationship, are called ‘modes’.
We should know that concept such as necessity and non-necessity, or necessary and unnecessary are evident and certainly need no definition for their presence in the mind, and even such concepts cannot be defined. These concepts are gradually and automatically are formed in the human mind. Therefore, we do not intend here to define these concepts, and have only tried to show to which concepts of the mind the philosophers refer by the terms ‘necessity’ and ‘non-necessity’.
Necessity and impossibility
The above-mentioned necessity and nonnecessity were not specific to any special attribute. In general, the relationship f each attribute with the thing it describes is either necessary or unnecessary, that is, it is either an attribute inseparable from that thing, or it is a separable attribute.
‘Even’, for example, is the necessary attribute of number eight, whereas whiteness is the unnecessary attribute of the flower. Now we turn our attention to existence and non-existence.
As the relationship of one thing and its attributes could be either necessary or unnecessary, the existence or nonexistence of one object could be necessary or unnecessary. In other words, the existence of one things can be necessary or unnecessary, and its non-existence can also be necessary or unnecessary. In technical terms, things that have a necessary existence are called ‘necessary’, and those whose non-existence is necessary are named ‘impossible’. The necessity of existence is also named ‘necessity’, and the necessity of nonexistence is called ‘impossibility’. So, when we say something is necessary, we mean its existence is necessary, it must exist, and its non-existence is impossible.
On the other hand, when we say something is impossible, we mean its non-existence is necessary, it should not exist, and its existence would be impossible.
For further clarification of the issue, let’s consider one of the phenomena, the storm, for example. Suppose that we know all the factors responsible for the existence of the storm, and decisively judge that the storm must exist. In other words, with this supposition the storm will necessarily exist, and, in philosophical terms, it is necessary. Now, suppose that some or all of these factors do not exist; then, according to the judgment of the intellect, the storm should not exist. In other words, with this supposition the storm would be necessarily non-existent, and in philosophical terms it would be impossible.
Impossibility by essence and impossibility by other
If we suppose that the causes and factors necessary for the existence of a storm do not exist, the storm will never exist. With this supposition, the storm should be impossible. Moreover, we are all familiar with concepts of ‘circle’ and ‘angle’, and we know that a circle can never have and angle. Therefore, an angled circle or a circle with an angle would be impossible.
Here we are faced with two impossible things; the storm and an angled circle. Is there any difference between these two impossible things? No doubt there is a difference. Although the storm is now impossible, we can do something to remove this impossibility; in other words, its impossibility is removable and separable, whereas the impossibility of an angled circle can never be lifted.
What is the origin of this difference? What is its cause? Its cause is that the impossibility of an angled circle emanates from its essence. What we mean by the essence of a particular thing is the thing itself, regardless of the existence or nonexistence of other things. Therefore, if we want to consider the essence of a thing, we must consider only that thing, irrespective of the existence or nonexistence of any other thing. The essence of an angled circle, then, would be impossible. Why? Because it is contradictory in its essence, circle being a closed equidistant curve that has no angle. An angled circle would be, then, a curve that both possesses and does not possess an angle. This, obviously enough, is a contradiction, and every contradiction, no doubt, in essence and in itself would be impossible. The storm, however, is not contradictory in itself; its impossibility is not a part of its essence so that it should be inseparable from it and make its existence automatically impossible; rather, its impossibility is caused by external factors, that is, things outside it have caused its impossibility.
There are certain obstacles, for example, preventing its existence, or there are certain factors that are necessary for its existence and have not been realized yet.
It is clear that once those barriers are lifted or those necessary causes are made available the storm will no longer be impossible. This is why philosophers argue that the existence of an angled circle would be ‘impossible by essence’ and its impossibility would be ‘an impossibility by essence’ or ‘essential impossibility’, whereas the existence of the storm, whose causes do not exist yet or there are certain obstacles preventing it, is ‘impossible by other’ and its impossibility is ‘impossibility by other’.
From what has already been said it becomes clear that the impossible by essence can never exist, and it is impossible to find any extension for it in the external world. It would not exist simply by changing states and situations, by stipulating new conditions, or by changing particular factors. The impossible by essence is absolutely nonexistent in any state, unlike the impossible by other, which though in the present state and situation and in the present condition cannot exist and can never have an extension, in certain cases by changing the state, situation or condition, and, in short, by changing the factors responsible or its impossibility, it can exist.
Necessity by essence and necessity byother
We are already familiar with the philosophical term ‘essence’. The essence of a particular thing is the thing itself regardless of other things; therefore, our conception of the essences of a thing would be equal to our conception of the thing without conceiving or stipulation the existence or non - existence of any other things. Considering the meaning of essence and the explanation given on the impossible by essence and the impossible by other, we can easily understand at the meaning of the necessary by essence and the necessary by other.
If there essence of a thing is necessary that is if exist necessary without the mediation of any other the influence of any other factor, dependence on any cause or condition or in short if it exists necessary by itself and in more simple term, if its non- existence is self-contradictory , such a thing would be necessary by essence it is evident that if the essence of a thing is not necessary , but it becomes necessary on stipulating certain causes and factors , such as thing would be necessary by other , for in fact , it is made necessary by external causes and factors ; it’s necessary is the result of those cause Therefore necessity by essence is that necessities which results from the thing itself and is dependent no on external factor necessity by other however result from something other than the thing itself.
From what has been said we may after that it impossible to annihilate the necessary by essence. We cannot make it non-existent by simply changing some states situation as or conditional or my producing certain factors the necessary by essence enjoys absolute existence under all circumstances. However though in the present situation , state and condition the necessary by other is necessary and con not be annihilated once the situation , state and condition change or in short as soon as the removal of the cause of it necessity become possible , it may lose its state of necessary existence and become non-existence .
We many mention many examples of the necessary by other. All the existent we may observe in our surroundings, such as different kinds of element, plants animal and men are necessary by other. The tree that we see is the effect is a claim of cause, such as water, air, certain, degree of temperature and many other factors that may not be easily enumerated. If this chain of cause stays as it is and none of the cause change, this tree will necessary continue existing, and it will never become non-existence. To destroy it, certain changes have to take place in this chain. In that case, the tree would not be necessary and is would become nonexistent.
This means that it the chain of these causes that makes the tree necessary and its non - existence impossible. Accordingly, by changing this claim its necessary might be lifted and it would become non-existent. The necessary by essence is limited to the existence of God. Philosophers have proved that it is only God who is necessary by essence.
Possibility by essence
So far we have understood that the impossible by essence is the thing which when conceived without conceiving the existence or non-existence of any other thing with itwe understand that is existence is self - contradictory, and therefore impossible In itself rather than because of any other factor. On the other hand, the necessary by essence is that which is necessary by itself - contradictory and is impossible and therefore its existence is caused by essence, that is it essence is necessary neither in its existence nor non- existence and neither its existence nor selfcontradictory such a thing would be possible by essence Possibility then means that neither existence nor nonexistence is necessary.
Therefore in order to understand whether a thing is possible by essences or not we have to conceive only that thing without considering the existence or non - existence of other things and examine it in regard to existence and non-existence and consider it position. If we find that it not contradictory i its existence that is tots existence is not impossible and also it is not contradictory in its non- existence, that is it non-existence is not impossible it will be possible by essence.
We can mention many examples of the possible by essence. All the things we find in our surroundings, including ourselves are possible by essence. However let us take the aforementioned storm as an example. you may be asked to consider only the existence of it cause or factor , or, in more philosophical; term to conceive only the essence of the storm, say if the thing you have considered can ever find an extension band whether its existence is self - contradictory. Your answer will be negative, and your reason will be that in the past there have been many storms. You might also be asked whether the non-existence if the thing you have considered is impossible, and if is non- existence will be lf contradictory.
Once again your answers will be negative, for usually she weather is claim and there is no storm. Therefore, the storm is essentially neither necessary nor impossible or in other words it possible by essence.
Compatibly of possibility by essence with necessity or impossibility by other
There is no doubt that possibility by essence is incompatible with necessary or impossibility by essence. In other words, the possible by essence can never become necessary or impossible by essence, for the possible by essence is that which in itself is necessary neither in its existence nor in its non- existence, whereas the necessary by essence or the impossible by essence is that which is necessary in its existence or in its non -existence , respectively. Therefore , there would be a contradiction and an impossibility if a thing could be both possible and necessary in its existence , Similarly there would also be a contradiction and an impossibility if a single thing could be both possible and impossible by essence , that is its non = existence be both necessary and unnecessary .therefore the possible by essence cannot be necessary or impossible by essence , that is possibility by essences in incompatible with necessity or impossibility by essence.
Now is possibility by essence also incompatible with necessity or impossibly by other? In other words, will there be any contradiction if the possible by essence could be the necessary or the impossible by other? The answer is no!
from the rational perspective there is no contradiction if a thing whose existence or non- existence is essentially not necessary to become necessary in its existence or non-existence by external factors just as it is not impossible for a thing that is not luminous in itself to become luminous by external factors, like iron for example which is itself is not luminous and becomes luminous through heating. Thus possibility by essence is compatible with necessary and impossibility by other. However this is not all for as we shall demonstrate in chapter eleven by priming the law of ‘causal necessary ‘everything that is possible by essence is simultaneously necessary or impossible by others.
Turning to the example of the storm mentioned above, this is why once we know that all the causes and factor of the storm are realized we will judge at once that the weather must necessary be stormy, and that is impossible for it to be otherwise. In other words the storm is necessary, by which of course, we mean it is necessary by others for allegedly this necessary is imposed on it by the cause and factors that create it. Now if at the time we proclaim the necessity of the storm we are asked if the same storm, irrespective of the causes of it creation, necessarily exists and is necessary in it, we will definitely reply in the negative at say that in itself it is still only possible.
The meaning of theses two simultaneous judgements made you the intellect is that from the rational point of view the mentioned storm is simultaneously possible by essence and between these two. In the same way, possible by essence is show to be compatible with impossibility other.