A chemist, for example, who undertakes a chemical experiment, hopes to discover the real properties of the substance he is working on, or to find the effects that can be related to an element under experiment. Likewise, a historian looking into the events responsible for the outbreak of the two World Wars is after the relationship of these historical phenomena with the causes and reasons which might have led to them.
In the course of his search, the scientist wishes not only to see that two things have some kind of relationship, but he also wants to discover which one is the cause or originator and which is the effect or product.
This is also true of human actions; for whatever man does is either voluntary, that is, according to his will and desire, or involuntary, that is, natural and forced. If it is voluntary, then we may say that the act is the effect of a thinker's thought, since it is he who, through thought, deliberation, and after weighing various alternatives, has made his choice, whereas involuntary actions are those which come about as a result of some bodily or natural causes.
It is impossible to conceive of a thing as coming into existence without a cause and by itself. Therefore, we may say that for a thing to exist there has to be something which is a cause of its existence. Thus, to define `cause', we may say that a cause is something from which some new thing called `effect' is born.
We may add that as long as the cause (that is whatever is required for origination of the effect) is not fully realized, the effect will not come to exist. On the other hand, if an effect comes into being, we can immediately assert that a cause has pre‑existed it.
From what we have said we can conclude that causality is a relation between two beings to the effect that the existence of one is a prerequisite for the existence of the other. In this interdependence, the effect is sequential and dependent on the cause. The principle of causality can be concluded from the following analysis:
There can be only two basic explanations regarding existence of a phenomenon:
a) It comes into being accidentally or by chance;1
b) It is the effect of a cause on which it depends.
If the first assumption is accepted, then we have to accept also, firstly, that there is no provable connection between things, or the effects produced by them. For example, there is no way of proving that the fruit is born of the tree, or a man's actions are attributable to him, and, as a result, one can deny one's acts to be one's own and readily regard them as being without causes or as being accidental.
Secondly, we must accept that there can be no valid scientific law; for every law of science is based upon the principle of causality and on the notion that every phenomenon is the product of a cause and dependent upon it.
Thirdly, it should also be accepted that no event can be predictable, that is to say we must allow that many things are probable to occur at every moment, for nothing is a precondition for any other thing.
It is obvious that the above three conclusions are invalid, and the assumption that chance and accident is responsible for emergence of phenomena cannot adequately explain the problem. Thus, we have no alternative except to accept the second assumption, which entails the acceptance of the causal relationship between things.
The principle of causality was looked upon by almost all philosophers except the empiricists as a reasonable way of explaining all phenomena, whether social or natural. It was the English empiricist David Hume who rejected the principle of causality, claiming that causal relationship is not what its exponents assert as an objective reality, but a subjective notion based on conjunction conceived by the mind between impressions.
But it has been proven that such an interpretation of causality leads to pure solipsism and complete denial of the external world. Incredibility of such a view is self‑evident.2 On the other hand, some Islamic philosophers hold that ideas such as causality and the like are intuitively obtained by the self through its direct knowledge of itself (`ilm huduri). So, it is claimed that not only the ideas of causality and substance, but all the basics of human knowledge are rooted in ‘ilm huduri .3
On the basis of what has been said, it is evident that causality is an objective, real and external relation, not a subjective formulation as empiricists claim it to be. Therefore, whenever a complete cause‑a cause which possesses all conditions necessary and sufficient for existence of the effect‑is realized in the external world, it is necessarily followed by the effect. Likewise, whenever we observe the effect as existing, we can conclude that its cause has already been existing.4
1. By `chance' here we mean occurrence of a phenomenon without cause. The word is also used for two other meanings: i) occurrence of a phenomenon through the agency of an unusual cause; ii) an unexpected outcome of an action which was not the premeditated goal of the doer.
2. See Paul Foulquie's Treatise on Metaphysics; Persian trans. by Y. Mahdawi. See also Comparative Ideology published by Dar Rah‑a Haqq Organization.
3. For more details see The Principles and Method of the Philosophy of Realism by `Allamah Tabataba'i, footnotes by Murtadha Mutahhari, vol. 2.
4. It should be noted here that causal precedence is not the same thing as temporal precedence. For example, when we move a pen, while writing, we usually say that the hand moves first, and then the pen follows the movement of the hand, or that the motion of the hand precedes that of the pen. However, they both move simultaneously. This type of precedence is called `causal precedence'.