A Critical Estimate of Hume's view on Causation

David Hume: ‘With Hume, the Modern Philosophy of Causation Begins’
Dr. Pushpa Rani Prasad

by Pushpa Rani Prasad

The idea of causation is one of the threadbare problems of philosophy and has been discussed both by the philosophers and the scientists from the dim past to the present age. Its root goes as far back as to Aristole. In the Cartesian philosophy, as in that of the scholastics, the connection of cause and effect was supposed to be necessary, as logical connections are necessary. The first really serious challenge to this view came from Hume. It has rightly been said that with Hume the modern philosophy of causation begins. In the opinion of Hume, no quality of any object which we consider a cause can be the origin of the idea of cause for there is no discoverable quality which is common to all objects. Hume points out that the idea of causation is derived from the relations such as contiguity, priority of time, constant conjunction and necessary connection. In his opinion the relation of cause and effect does not depend much on the relations of contiguity, succession and constant conjunction. The central theme of Hume’s entire argument is to point out how experience gives rise to the idea of necessary connection. He concludes that necessity is something which exists in mind, not in objects. It is nothing but that determination of thought to pass from causes to effects and from effects to causes, according to their experienced union. Belief in causation is due to custom-born association. Necessary connection is not an affair of reason but of imagination.

The oldest view on the issue of causation is that of the rationalists. According to them causation is a necessary connection between cause and effect, which is true for all the time. Hume's view of causation keeps an important place in the history of philosophy. Causation has been viewed by Hume both as a philosophical relation and a natural relation. Considering as a philosophical relation cause has been defined by Hume as:
"An object precedent and contiguous to another, and where all the objects resembling the former are placed in like relations of precedency and contiguity to those objects that resemble the latter".1
Causation as a natural relation has been defined by Hume as “A cause is an object precedent and contiguous to another and so united with it that the idea of one determines the mind to form the idea of the other, and the impression of the one to form a livelier idea of the other”.2
Hume divides all the objects of human inquiry into 'relations of ideas' and 'matters of fact'. The former includes those ideas which are either intuitively or demonstratively certain. The relations of matters of fact are identity, situation in time and place and causation. Hume says that all kinds of reasoning consist in nothing but a comparison and a discovery of those relations, either constant or inconstant, which two or more objects bear to each other. This comparison may be made either when both the objects are present to the senses, or when neither of them is present, or when only one. When both the objects are present to the senses along with the relation, we call this perception rather than reasoning. In it there is no exercise of thought but admission of impression through the organs of senses only. In the case of comparisons of identity and relation of time and place the mind is concerned with what is actually there. Observations we make concerning identity and time and place cannot be treated as reasoning, since in none of them mind can go beyond what is immediately present to the senses.
The relation of cause-effect informs us of existences and objects which we do not see or feel. So, this relation needs philosophical analysis. Hume proceeds to examine the idea of cause by searching for impression or impressions from which it is derived. In the opinion of Hume, no quality of any object which we consider a cause can be the origin of the idea of cause for there is no discoverable quality which is common to all objects.
So, the idea that of causation must be derived from some relation among objects which Hume now endeavours to discover.
The relations which Hume discovers are:
(i)                Contiguity
(ii)              Priority of time (the cause prior to effect)
(iii)           Necessary connection.

(i)    Contiguity:
 Hume finds that whatever objects are considered as cause and effects, are contiguous and nothing can operate in a time or place which is ever so little removed from those of its existence. Though distant objects may sometimes seem productive of each other, they are commonly found upon examination to be linked by a chain of causes, which are contiguous among themselves and to the distant objects. Hume, thus, considers the relation of contiguity as essential to that of causation.

(ii)   Priority of time (succession):
The second relation which we find between cause and effect is that of 'priority of time'. It is generally observed that in the cause and effect series, cause comes earlier in time and the effect follows later in time. Succession in time is always observed. For instance, when we switch on, the lamp is lighted. Here the cause ‘switch on’ comes prior to the effect the 'lightening of lamp'.
It would be untrue to say that Hume lays great emphasis on contiguity and on temporal succession as essential elements of causal relation. He says,
"An object may be contiguous and prior to another without being considered as its cause. There is a Necessary Connection to be taken into consideration; and that relation is of much greater importance than any of the other two above-mentioned".3
Hume points out that sounds and smells, passions and volitions cannot properly be said to have shapes or positions at all, but do enter into causal relationship. It is not, therefore, his final opinion that spatial contiguity is an essential part of causation as regards the question of time relation between cause and effect, Hume never clears up. He gives what purports to be an argument to show that effect must follow cause in time. 

(iii)  Necessary Connection:
Hume finds that the relation of cause and effect depends not in the least on known qualities of objects considered as cause. The relations of contiguity and succession have already been regarded as imperfect and unsatisfactory.
The two questions which Hume now proceeds to examine are:
(1)     "First, for what reason we pronounce it necessary that everything whose existence has a beginning should also have a cause?
(2)     Secondly, why we conclude, that such particular causes must necessarily have such particular effects; and what is the nature of that inference we draw from the one to the other, and of the belief we repose in it?
The first question is concerning the necessity of a cause. Hume says it is a general maxim in philosophy that whatever begins to exist must have a cause. This is commonly taken for granted in reasoning without any proof given or demanded. Hume asserts that idea of necessity is neither intuitively nor demonstratively proved to be certain. Hume says that as we cannot derive the opinion of the necessity of a cause to every new production from knowledge or any scientific reasoning, that opinion must necessarily arise from observation and experience. The next question then, should naturally be, how experience gives rise to such a principle? Hume thinks that the answer to this question will be found perhaps in answering the second question.

Nature of Causal Inference:
According to Hume when we infer effects from causes, we must establish the existence of these causes which can be done only by immediate perception of our memory or senses. It is impossible for us to carry on our inferences in infinitum. So all the reasoning concerning causes and effects are originally derived from some impressions. In causal inference we find that when we have the perception of cause or of effect only, its correlative is inferred in idea. Causal inferences, thus, contain a present perception either of sense or memory, and an idea reached by inference.
In the opinion of Hume, the ultimate cause of the impressions which arise from senses is perfectly inexplicable by human reason and that such a question is not in any way material to the present purpose. As regards ideas of memory Hume says, "Since therefore the memory is known neither by the order of its complex ideas, nor the nature of its simple ones; it follows that the difference betwixt it and the imagination lies in its superior force and vivacity".4
Hume says that it is merely the force and liveliness of the perception which lays the foundation of that reasoning which we built upon it, where we trace the relation of cause and effect. Hume says that the belief or assent which always attends the memory and senses is nothing but vivacity of those perceptions they present.
Now Hume proceeds to examine the inference which we draw from cause (impression), to effect (idea). Hume is of the view that one does not in fact need to survey particular objects or make any penetration into the real essences of things when we discover causal connections. The discovery is not derived from any such penetration.
So, separation of cause and effect implies no absurdity and self-contradiction. Effect being distinct from its cause can never be discovered in it, any conception of it a priori must be entirely arbitrary.
Had causation been a logical relation, then the contradictory of every true proposition which asserted a causal connection would be self-contradictory. In that case the proposition which asserted the existence either of general or of particular causal connections would have been analytic, which is not a fact. It is very likely that the course of Nature may change, and our previously experienced result may be attended with different or contrary effects. He cites the example of a body, falling from the clouds that it may resemble snow in all other aspects, but has the taste of salt or feelings of fire. Thus, Hume rightly thinks that it is only by experience that the validity of any synthetic proposition can be determined. It is therefore by experience only, that we can infer the existence of one object from that of another.
Hume advances a general description of the experience that is causal inference. Explaining the nature of experience Hume says that we remember to have had frequent instances of the existence of one species of objects; and also remember that the individuals of another species of objects have always attended them and have existed in a regular order of contiguity and succession with regard to them. For example, "we remember to have seen that species of object we call flame, and to have felt that species of sensation we call heat. We likewise call to the mind their constant conjunction in all past instances. Without any farther ceremony, we call the one cause and the other effect, and infer the existence of one from that of the other".5
Thus, a new relation between cause and effect has been discovered. This relation is their constant conjunction. Contiguity and succession are not sufficient to make us pronounce any two objects to be cause and effect, unless we perceive, that these two relations are preserved in several instances. Constant conjunction implies that like objects have always been placed in like relations of contiguity and succession.
Hume points out that the newly discovered relation of a constant conjunction seems to advance us very little in our way. In his opinion what we learn not from one object, we can never learn from a hundred, which are all of the same kind, and are perfectly resembling in every circumstance. It is clear that constant conjunction cannot by itself be the origin of the idea of necessary connection. But Hume points out that we make causal inference, which consists in a "transition from an impression or memory of one object to the idea of another which we call its cause or effect, whenever we have experience of constant conjunction.
Hume says that if reason determined us to make the transition it would proceed upon that principle "that instances, of which we have had no experience, must resemble those, of which we have had experience, and that the course of nature continues always uniformly the same".6
Hume now considers all those arguments upon which such a proposition may be supposed to be founded and which must be derived either from knowledge or probabilities. Hume says that there can be no demonstrative arguments to prove that those instances, of which we have had no experience resemble those, of which we have had experience. It is not an analytic proposition; whose contradictory is inconceivable. A change in course of nature is perfectly conceivable. Probability, in its distinction from demonstration, does, indeed, rest on an appeal to experience, but it concerns only those happenings in regard to which there is a conflict of experience.
It is clear that 'reason' can never show us the connection of one object with another, though aided by experience, and the observation of their constant conjunction in all past instances. Giving a solution of this dilemma Hume says that when the mind passes from an idea or impression of one object to the idea or belief of another, it is not determined by reason, but by certain principles, which associate together the idea of these objects, and unite them in imagination. He says:
“Thus, in transition from an impression of one object to an idea of another, it is the imagination which is operating, not understanding. It is custom and not reason, habit and not evidence, which is at work”.7
Custom or habit here operates in and through the laws of association; and it is upon this associative union of ideas that the inference rests. We find that from the constant conjunction the objects acquire a union in the imagination and when an impression of one becomes present to us, we immediately form idea of its usual attendant.

The idea of Necessary Connection:
After explaining the manner in which we reason beyond our immediate impressions and conclude that such particular causes must have such particular effects, Hume returns to examine the question raised earlier viz. what is our idea of necessity, when we say that two objects are necessarily connected together. As there is no idea that is not derived from some impression, Hume proceeds to find some impression that gives rise to this idea of necessity when the two objects are supposed to be placed in causal relation. It is perceived that they are contiguous in time and place and that the object we call cause precedes the other we call effect. The relation of constant conjunction also does not help much and does not give rise to a new idea.
Hume has also examined the question concerning the power and efficacy of causes which has caused much disputes both among ancient and modern philosophers. Hume observes that efficacy, agency, power, force, energy, necessity and productive quality are all nearly synonymous and tries to find impression from which the idea of power or efficacy is originally derived.
Thus, according to Hume, if two objects are presented to us, of which one is the cause and other the effect, it is plain from any one instance we never arrive at the idea of cause and effect, of a necessary connection of power, of force, of energy and of efficacy. When we observe several instances, in which the same objects are always conjoined together, we immediately conceive a connection between them and begin to draw an inference from one to the other. This multiplicity of resembling instances, therefore, constitutes the very essence of power or connection, and is the source from which the idea of it arises. The repetition of perfectly similar instances can never alone give rise to an original idea, different from what is found in any particular instance which is also evident from the fundamental principle that all ideas are copied from impression.
Hume says after we have observed the resemblance in a sufficient number of instances, we immediately feel a determination of the mind to pass from one object to its usual attendant, and to conceive in a stronger light upon account of that relation. This determination is the only effect of the resemblances, and therefore must be same with power or efficacy, whose idea is derived from resemblance. Necessity then is the effect of this observation and is nothing but an internal impression of the mind, or a determination to carry our thoughts from one object to another. There is no impression conveyed by our senses which can give rise to that idea. It must, therefore, be derived from some internal impression or impression of reflection. There is no internal impression but that propensity which custom produces, to pass from an object to the idea of its usual attendant. So the necessity is something which exists in mind, not in objects. Necessity is nothing but that determination of the thought to pass from causes to effects and from effects to causes, according to their experienced union.
Hume's commentators have assumed that Hume questions the validity of the causal maxim. But he cannot be accused of denying causation; rather he was concerned with defining it properly. The question is not whether there are causal relations. Hume's discussions concern only the grounds upon which the causal belief rests. All that Hume denies is that there is any secret tie between cause and effect due to which one can necessarily produce the effect. Hume finds a substitute for this alleged power which he calls 'determination of the mind'.
Some modern thinkers have appreciated Hume's views. The concept of regular succession given by Hume can be observed by differentiating two phrases, “after this" and "because of this". The meaning of "because of this", is entirely different from 'after this'. The logical positivists maintain that actually one observes regularity or uniformity of sequence between the events. They would therefore agree with Hume that the only thing which distinguishes a purely temporal sequence i.e. "this after that ", from causal "this because of that", is the greater regularity of the latter.
Russell also believes that from practical point of view causation is same as the varying sequence. It means that Russell accepts Hume's view of causation as regular sequence.
Smith remarks that if necessary connection is not revealed in one instance, it is also not revealed in any number of similar instances. He says, "It is precisely the similarity of the instances which constitutes the uniformity, and which therefore rules out the possibility of more being revealed by additional instances than is revealed in single instance".8
Because nothing is given in one instance, repetition or uniformity cannot be made the basis of inference to the future either demonstrative or probable. Smith holds, therefore, that what one requires is that the enlargement of experience which will supply us, what neither single instance not the mere repetition of similar instances can yield.
What Hume had done in connection with the idea of necessary connection is to have redefined the idea. By redefining the idea as a feeling of connection in our mind, he saves the idea from the fate of being condemned as meaningless. It follows from the redefined idea that the traditional notion of necessary connection is rejected. The traditional meaning is shown to have no application, since it had no corresponding impression. The most important conclusions which Hume arrives at as regards causal relation are that belief in causation is due to custom-born association and that necessary connection between cause and effect is never perceived. It is not an affair of reason but of imagination.
We find that Bertrand Russell has supported Hume's view. In his book 'History of western philosophy' he writes: “So far as physical sciences are concerned, Hume is wholly in the right, such propositions as 'A causes B' are never to be accepted, and our inclination to accept them is to be explained by the habit and association”.9
A.J. Ayer is also of the opinion that causal connection belongs to the class of synthetic propositions. He writes “We have indeed, no a priori ground for either accepting or rejecting the doctrine that every event is causally connected with every other, but there are good empirical grounds for rejecting it".10
It was recognized by Hume that when we look towards external objects we are never able to discover any power or necessary connection. There is, Hume says, nothing in a number of instances, different from any single instance, which is supposed to be exactly similar, except only that after a repetition of similar instances the mind is carried by habit, upon the appearance of an event to except its usual attendant, and to believe that it will exist. This connection, therefore, which we feel in the mind, this customary transition of the imagination from an object to its usual attendant, is the sentiment or impression from which we form the idea of necessary connection.

Thus, in my opinion at least this much is important about Hume, that his main interest is neither to provide a psychological nor any objective account of this principle; rather his main effort seems to present a conceptual analysis of causation. It still remains a doubtful proposition whether or not he has unfolded the idea of causation as it lies within the mind, or has he explained it adequately as a natural law? The main reason of all the misunderstandings is the lack of proper appraisal of Hume's position. While providing this account, Hume was very much cautious that he was not going to propound this stupid doctrine that an event can take place without any cause, rather he simply wanted to point out that the notion of causal necessity can neither be known through perception nor through inference, rather it is only the product of our faith, imagination and habit. He intends to dethrone the concept of causation as a necessary connection because the idea of cause has been the bedrock of traditional cosmology, theology and ethics. In fact, Hume's attempt is quite praiseworthy to the extent that he has evoked the scientists and philosophers to think this problem a fresh on empirical light. And this has produced a good effect on the logical empiricists like Russell, Carnap, Ayer etc. Blanshard has pointed out that "Russell and Wittgenstein have almost returned to Hume's conclusion".11
Hume has deduced the conclusion keeping his view on his basic premise that "all the perceptions of human mind resolve themselves into two distinct kind, which I shall call "impressions" and "ideas" and this part of Hume's attempt is still a landmark in the field of recent philosophy which drew the attention of large number of philosophers. Challenging the traditional concept of causation as a necessary connection, Hume attempted a re­examination of the very idea of causation for a correct appraisal. And here again, Hume seems to be the precursor of the logical empiricism whose job is also the same.

1. Hume, David:            A Treatise of Human Nature; Ed. by L.A. Selby-Bigge, The Clarendon Press, Oxford-1958, p-170.
2. Ibid: p-170.
3. Ibid: p-77.
4. Ibid: p-85.
5. Ibid: p-87.
6. Ibid: p-89
7. Ibid: Abstract, p-16 quoted in The Philosophy of David Hume, by N.K. Smith, p-375.
8. Smith, N.K.:  The Philosophy of David Hume, London, Macmillan & Co. Ltd., 1964, p-394.
9. Russell, Bertrand:      History of Western Philosophy; George Allen & Unwin Ltd., London, 1961, pp-642-643
10. Ayer, A.J.:   Languate, Truth and Logic; Victor Gollancz, London, 1967, p-151.
11. Blanshard, Brand:    Reason and Analysis, George Allen & Unwin Ltd., London, 1962, p-445.
About the Writer:
Dr. Pushpa Rani Prasad, a Commissioned acting Principal working at S.P. Mahila College, Dumka, Jharkhand (India) writing in both English and Hindi. She is a pioneer of modern vision and her voice for modern Indian women is miracle and outstanding.

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