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Ideas: Hume's Problem of Induction

1.01.2006

The first in a series of posts concerning some philosophical themes. I have no intention of sticking to a regular day. Some of this stuff will be abstract, but it is my intention to try to bring some of the issues at the heart of these discourses into a more practical light. I am starting with Hume's fork for no other reason than it is part of my revision.

David Hume set out in his Enquiry Concerning Human Understanding, available online here, an examination of the nature of causality and necessity in relations between objects. The following is a small attempt to draw out some of its content and examine its relevance.

David Hume considered there to be two major types of human understanding. We can only come to know things:

1)Through Demonstrative Reasoning (Analytic a-priori): i.e. only through relationships between ideas. This basically amounts to what we would consider logical operations on ideas. These are things which can be known intuitively and without experience.

It is thus referred to as analytic in that it examines the content of an idea without adding anything to it. Hume would have included mathematics, Geometry and Logic in this category.

That the sum of the angles in a triangle = 180 degrees is a piece of Demonstrative reasoning where the definition of a triangle is used to deduce the sum of its angles. Or that 2 x 10 = 4 x 5 is a true is a relation between two sets of numbers which can be known purely through thinking.

There is then the possibility of certain knowledge through this process of demonstrative reasoning. From a given definition or thought we can be sure of and deduce certain things. However demonstrative reasoning tells us nothing new about the world since it is concerned with relation between ideas. Truth in this case does not depend on existences of objects i.e. an imagined triangle will suffice to ensure truth. Thus it is a-priori knowledge knowable without experience.

2)Second is understanding through matters of fact. These is experiential and knowledge is received through the senses about the world. Matters of fact are facts about the world, gathered throught the senses, knowledge of the world is only possible through sense-perception of the physical world i.e. empirically but these are not as certain as truths of reason. The contrary to a matter of fact can be imagined as true so its ultimate certainty cannot be verified.

So we have now our basic pieces of Humes theory of knowledge. We can know the world only through experience and can also have some knowledge of ideas through logic and other operations. However to know of the world is to solely rely on empirical data.

So we now have two means to knowledge. Let us examine then some facts we might be considered to "know".

1)The sun will rise tomorrow (though I havent experienced it yet)
2)George Bush exists (though I haven't met him)
3)There is a wall behind me (even though I cannot see or feel it)

All of the above seem perfectly reasonable to us, however Hume asserts that these propositions are in fact beliefs, since we do not have direct experience of them being true.

However, in the absence of direct empirical knowledge of the above and a vast majority of much or our knowledge, Hume asserts that these must be considered as beliefs. If it is true as Hume argued above, that all knowledge is received through sense experience, how can we know the above to be true?

Hume says that the above facts should be seen as the result of cause and effect reasoning, where we have applied some form of causal logic to the fact:

1)Obviously I cannot experience tomorrows dawn until tomorrow, yet in all past experience the earth has rotated around the sun and caused sunrise and it should tomorrow
2)I havent met him, but many journalists, academics, historians agree on his existence, how could that be unless he existed?
3)Walls do not just disappear unless there is a tremendous crash thus it must be there.

The operation of causal logic in this instance has allowed us to move beyond matters of fact gathered directly to knowing other 'facts' about the world.

Hume asserts that the above process is used by us in our everyday life to substantiate and justify our beliefs in matters of fact which we cannot verify through our direct sense experience.

However, how can we know that all of the above reasoning is certain?
Hume argues that all of the three arguments above which justify our beliefs are based on an assumption that we cannot justify through reason. Each assume that there is a uniformity to nature that exists into the future and guarantees that like causes will have like effects. All of the above arguments suppose general laws of nature which assert continuity in behaviour through past present and unobserved future.

While it suits us to accept this belief for everyday living, Hume argues that we cant rationally assert the uniformity of nature into the future because we can logically conceive of it being otherwise. The challenge he lays down is to substantiate ones belief in the continuity of natural laws into the future through reason.

Hume asserts that cause and effect do not lie in the a-priori and cannot be used independently experience. Present an object to an intelligent man and no amount of observation of the object empirically (i.e. through the senses alone) will yield its causes or its effects. We thus rely on prior sense knowledge to substansiate causal assumptions.

To take Hume's own example: Would Adam have known from the transparency of water, that
it would drown him?

This is Humes problem of induction, that we cannot gather from past experience any data that will give us certainty about the future since there exists no real and causal relationship between past and future action. We’ve seen that

(1) our basic matter-of-fact beliefs depend on cause-effect inferences; and
(2) cause-effect inferences depend on the assumption that ‘nature is uniform’.

Thus while philosophy has sought to lend justification to our most fundamental beliefs, this is one of the most fundamental tenets of our thought which struggles to be rationally supported directly. The use of scepticism by Hume in approaching our causal reasoning has cast doubt on the possibility of certain knowledge.

Take this problem for example:

I am sitting on a chair in a square, empty room with only one door, four walls and no windows. I get up to leave this boring room and shut the door behind me as I leave. I believe that the room still exists behind that door even though I cannot be certain thereof. Is there any manner in which I can create a rational argument for the existence of that room right now without my direct experience of it.

From the above position, it seems that at best what I am doing is engaging in a pragmatically justified belief, yet one which cannot be fully rationally supported.

All this means is that all our reasonings about matters of fact are inferences based solely on how things have been in past experience (until we experience otherwise) -- but that is o.k.; for Hume, causal beliefs are both unavoidable and pragmatically justified. Yet nonetheless still beliefs.

From Humes Enquiry, Section 4:

---

If you are not yet convinced that absolutely all the laws of nature and operations of bodies
can be known only by experience, consider the following. If we are asked to say what the effects will be of some object, without consulting past experience of it, how can the mind go about doing this? It must invent or imagine some event as being the object’s effect; and clearly this invention must be entirely arbitrary. The mind can’t possibly find the effect in the supposed cause, however carefully we examine it, for the effect is totally different from the cause and therefore can never be discovered in it. Motion in the second billiard ball is a distinct event from motion in the first, and nothing in the first ball’s motion even hints at motion in the second. A stone raised into the air and left without any support immediately falls; but if we consider this situation a priori we shall find nothing that generates the idea of a downward rather than an upward or some other motion in the stone.

Just as the first imagining or inventing of a particular effect is arbitrary if it isn’t based on
experience, the same holds for the supposed tie or connection between cause and effect - the tie that binds them together and makes it impossible for that cause to have any effect but that one.
...
In short, every effect is a distinct event from its cause. So it can’t be discovered in the cause, and the first invention or conception of it a priori must be wholly arbitrary. Furthermore, even after it has been suggested, the linking of it with the cause must still appear as arbitrary, because plenty of other possible effects must seem just as consistent and natural from reason’s point of view. So there isn’t the slightest hope of reaching any conclusions about causes and effects without the help of experience.

---

The reason for Humes concern for cause and effect reasoning is that he saw it as the only way of going beyond our own experience and memories to further knowledge. Thus the operation of cause and effect reasoning is central to development of metaphysics and other non-physical forms of enquiry since we cannot experience them in any fully physical way. The obvious fallout from Humes problem is to cast doubt on the validity of moral inquiry and other related pursuits.

Hume's scepticism about causality posed a major challenge to the cosy assumptions of nearly 2000 years of philosophical thought. Philosophers were no longer entitled to arbitrarily use causal reasoning to further our knowledge of the world. It first had to be justified as a valid means of inducing fact from knowledge we already have. It required a justification of its existence as a tool which was valid in rational argument. It is not sufficient for custom to suffice as the basis of causal reasoning since this is open to being seriously flawed.

The challenge has still to be met to the satisfaction of all. Indeed this problem is cited by Kant as the major inspiration for much of his later work. In order to preserve causality as more than a pragmatice manner of dealing with the world we need to go over Hume's argument very carefully.

At this point, I should probably give some responses etc. I reckon its best to leave those to a subsequent post, assymilating some comments too if there are any. The next section will hopefully look at some responses and then the related topic of necessity which will conclude the post.

No idea when it will be, hopefully soon.

RR
Categories: Philosophy, Hume, Empiricism, Induction, Causality,

This entry was posted on 1.01.2006 at 1/01/2006 07:25:00 p.m.. There are . If you want, you can leave your own response by clicking here. You may also send this post to a friend of yours via email, or bookmark it for yourself by using icons below;