Part I

Knowledge is either about relations of ideas or matters of fact.

Relations of ideas

  • are intuitively or demonstratively certain.
  • “can be discovered purely by thinking, with no need to attend to anything that actually exists anywhere in the universe.”
  • include Geometry, Algebra, and Arithmetic. (e.g. Pythagoras’ theorem; 3x5=30÷2)

Matters of fact

  • are not intuitively or demonstratively certain.
  • “The contrary of every matter of fact is still possible, because it doesn't imply a contradiction” From a logical point of view, the affirmation “the sun will not rise tomorrow” makes as much sense as the proposition “the sun will rise tomorrow”. We can only demonstrate the falsehood of a proposition a priori if the proposition implies a contradiction (e.g, we can demonstrate that there is no “squared circle”).

Reasonings concerning matter of fact are not discoverable by thought alone but there are two ways in which we can obtain knowledge about matters of facts:

  • through the present testimony of our senses or the records of our memory, or
  • by reasonings.

“All reasonings about matters of fact seem to be based on the relation of cause and effect.” From considering the effect I can draw a conclusion about the cause:

  • I receive a letter from my friend in France, and I infer that, as a matter of fact, my friend is in France.
  • “Someone who finds a watch or other machine on a desert island will conclude that there have been men on that island.”
  • “Hearing the sounds of someone talking rationally in the dark assures us of the presence of some person.”

The causal connection between them may be collateral rather than direct—“as when one sees light and infers heat, not because either causes the other but because the two are collateral effects of a single cause, namely fire”—but I can never know anything about a matter of fact (the existence or non-existence of something) by mere thought:

“I venture to assert, as true without exception, that knowledge about causes is never acquired through a priori reasoning, and always comes from our experience of finding that particular objects are constantly associated with one other.” (i.e. constantly conjoined.)

Prior to experience “Adam…could not have inferred from the fluidity and transparency of water that it could drown him, or from the light and warmth of fire that it could burn him.”

Everyone will agree that this is so in cases

  • that were previously unknown to us (polished pieces of marble sticking together)
  • that are different to the norm (gunpowder or magnetism)
  • “when an effect is thought to depend on an intricate machinery or secret structure of parts” (why milk and bread nourishes a man but not a tiger)

It may be more difficult to accept but it is also true when the case concerns things that are familiar, normal or simple, e.g. the motion of billiard balls.

There is a reason why we can’t conclude a priori from the effect to its cause:

“…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.”

Without contradiction we can imagine billiard balls behaving in all sorts of ways or dropped stones not falling to the ground. Without experience there is no way to chose between the alternatives.

Applied mathematics doesn’t help because “every part of applied mathematics works on the assumption that nature operates according to certain established laws…but the law itself is something we know purely from experience, and no amount of abstract reasoning could lead us one step towards the knowledge of it.”

 

Part II

“What are inferences from experience based on?”Hume offers only a negative answer:

“…even after we have experience of the operations of cause and effect, the conclusions we draw from that experience are not based on reasoning or on any process of the understanding.”

The problem is that we do conclude from past experience to future events. If something has the same sensible qualities (i.e. qualities we experience through the senses) we expect it to have the same effects—if it looks and feels like bread we expect it to nourish us like bread has done in the past.

However,

“all that past experience can tell us, directly and for sure, concerns the behaviour of the particular objects we observed, at the particular time when we observed them.”

My experience tells me that fire consumed coal then but it does not tell me about other fires at any other time. Bread nourished me but it doesn’t follow that it will next time.

There does not seem to be any step of reasoning that can take us from

“I have found that such and such an object has always had such and such an effect”

to

“I foresee that other objects which appear similar will have similar effects”.

The reasoning cannot be either demonstrative (i.e. concerning a relation of ideas) or probable (i.e. concerning a matter of fact).

That no demonstrative reasoning is involved (i.e. it is not a relation of ideas) seems clear “since there is no outright contradiction in supposing that the course of nature will change so that an object that seems like ones we have experienced will have different or contrary effects from theirs.” e.g.

  • snowy stuff falling from the clouds might taste salty.
  • trees might flourish in December and lose their leaves in June.

Similarly it cannot be the kind of reasoning that concerns matters of fact because:

  1. all arguments about existence are based on the relation of cause and effect;
  2. our knowledge of that relation (i.e. cause and effect) is derived entirely from experience; and
  3. in drawing conclusions from experience we assume that the future will be like the past.

So, if we try to use this kind of reasoning to prove that the future will be like the past “we shall obviously be going in a circle, taking for granted the very point that is in question.”

“Only a fool or a madman would ever challenge the authority of experience or reject it as a guide to human life, [but] perhaps a philosopher may be allowed to ask what it is about human nature that gives this mighty authority to experience.”

“Our inferences from experience all boil down to this: From causes that appear similar we expect similar effects. If this were based on reason, we could draw the conclusion as well after a single instance as after a long course of experience. But that isn't in fact how things stand.”

Even where there is a repeated experience there is no process of reasoning involved.

“It may be said that from a number of uniform experiences we infer a connection between the sensible qualities and the secret powers; but this seems to raise the same difficulty in different words. We still have to ask what process of argument this inference is based on.”

“As soon as the suspicion is planted that the course of nature may change, so that the past stops being a guide to the future, all experience becomes useless and can't support any inference or conclusion. So no arguments from experience can support this resemblance of the past to the future, because all such arguments are based on the assumption of that resemblance. However regular the course of things has been, that fact on its own doesn't prove that the future will also be regular.”

That this drawing of a conclusion based on experience isn’t a process of reasoning is shown by the fact that

“the most ignorant and stupid peasants, even infants, indeed even brute beasts, improve by experience and learn the qualities of natural objects by observing their effects.”

An example would be the child and the candle flame. If a process of argument is involved it must be simple enough for the child and so anyone who thinks that some kind of argument is involved should be able to say what it is.

 

 

 

Last modified: Friday, 27 August 2021, 6:57 PM