On Philosophy

June 4, 2006

Knowledge of Causation

Filed under: Epistemology — Peter @ 3:39 pm

Famously Hume asked “how do we know that one thing is the cause of another?’ (not in those exact words mind you) Although we can observe events and the passage of time we can never observe causation itself. There are no “causation particles” that can be examined by science. This led Hume to develop his famous problem of induction, where he showed that causation is simply a guess, not knowledge. After observing a large number of event Y followed by event X we guess that Y is the cause of X, but since we don’t know that Y really is the cause of X we can never be sure that there might not be some future case in which Y isn’t followed by X.

Now that I have presented a different account of causation let me apply that account to this problem. Ultimately my account does not rest on assumptions about what is or is not a cause, but our assumptions about how the world changes over time. Recently we have codified these assumptions into physical laws, but it is not necessary to have a formal system such as this to make claims about causation. Our assumptions about how the world changes over time generally do not include claims about causation built into them. For example the claim that objects fall towards the ground doesn’t involve the notion of causation at all. I claim that once we have these laws we then deduce causes from them (by a process of speculating as to what was necessary for an event to occur). Thus we never have to observe causation directly to have knowledge concerning it.

Unfortunately this doesn’t solve the problem of induction, it simply changes its target. Now we have to answer “how do we know that our physical laws will be true in the future?” Even though our laws may explain all of our observations perfectly we have no assurances that they will continue to apply to our future observations. Some might answer this formulation of the problem of induction with a falsificationist line of argument (a hypotheses should be considered true if it is possible to falsify it and so far nothing has). Not everyone accepts falsification as a basis for knowledge, and I will leave a defense of it for a future date, but at least we have saved our knowledge of causation from being vulnerable to the problem of induction.

Causation: Update

Filed under: General Philosophy — Peter @ 12:53 pm

This post in an addendum to this post.

The equations that I used to define causation may need to be revised slightly to handle two kinds of cases, both of which used in the main body of the text, but which I did not explicitly define.

One case is where you are looking for the cause of a set of properties (“particles”). In this case we define z and DC as follows:

Under this definition the single particle case is covered when z is a set containing only one element.

A more complicated situation arises when the condition you wish to determine the cause of is not determined by any one state of the world. For example one of the applications I provided was determining the cause of a man’s death. However the state we are looking for, a dead man, is not determined uniquely by any one configuration. In this case we have to abandon first order logic and define z (or Z) as a predicate. We could then define Z to be true whenever the man is dead, and Z would then hold no matter how he died. In this case our definitions are like so:

The simpler cases where we are only testing for the cause of the state of a single “particle” or when we are testing for the cause of a set of particles can be recovered by defining Z as:
Single particle case: where p is the particle state we are interested in.
Set of particles case: where p1, p2, … are the particle states we are interested in.

Neither of these revisions however makes a difference to how C is defined, so they can be safely ignored when considering the cause of macroscopic objects, since we are only working with an approximation in those cases anyways.

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