Causality

Causality, the relationship between causes and effects, is of importance in a knowledge representation system. The causation relation will be a relation between states of affairs, events, situations or situoids. A situoid, situation or state of affairs $A$ is the cause of the situoid, situation or state of affairs $B$ if $A$ is the reason that brings about the effect $B$. However, this is somewhat circular, as it has to be clarified what it really means that $A$ is the reason that $B$ occurs.

David Hume held that causes and effects are not existent or at least not knowable, but imagined by our mind. Only correlations can be observed, but not causations.

But there are many philosophers that believe in causation. If one event $A$ is the cause of $B$, then $A$ and $B$ occur usually in a temporal sequence, $B$ after $A$. But it is not the case that a situoid $A$ causes the situoid $B$ just because $B$ follows right after $A$. There is even a logical fallacy, known as ``post hoc ergo propter hoc'' (after this, therefore because of this).

Strictly speaking, if $A$ causes $B$, then $A$ must always be followed by $B$. A major problem is, that correlation does not imply causation. If two events occur usually together, they are correlated, but it is not necessary that one event causes the other event.

We believe that states of affairs, situations and situoids provide enough structure to give an account for causality. There are theories that allow only events to enter into causal relationship with each other. We believe, that, at least on the mental stratum, instantaneous states of affairs and situations may enter into causal relation with each other or situoids and other states of affairs.

However, more research has to be done on causality.