Editing Causality (section)

=== Probabilistic causation ===
{{Main|Probabilistic causation}}
Interpreting causation as a [[Determinism|deterministic]] relation means that if ''A'' causes ''B'', then ''A'' must ''always'' be followed by ''B''. In this sense, war does not cause deaths, nor does [[Tobacco smoking|smoking]] cause [[cancer]] or [[emphysema]]. As a result, many turn to a notion of probabilistic causation. Informally, ''A'' ("The person is a smoker") probabilistically causes ''B'' ("The person has now or will have cancer at some time in the future"), if the information that ''A'' occurred increases the likelihood of ''B''s occurrence. Formally, P{''B''|''A''}≥ P{''B''} where P{''B''|''A''} is the conditional probability that ''B'' will occur given the information that ''A'' occurred, and P{''B''} is the probability that ''B'' will occur having no knowledge whether ''A'' did or did not occur. This intuitive condition is not adequate as a definition for probabilistic causation because of its being too general and thus not meeting our intuitive notion of cause and effect. For example, if ''A'' denotes the event "The person is a smoker," ''B'' denotes the event "The person now has or will have cancer at some time in the future" and ''C'' denotes the event "The person now has or will have emphysema some time in the future," then the following three relationships hold: P{''B''|''A''} ≥ P{''B''}, P{''C''|''A''} ≥ P{''C''} and P{''B''|''C''} ≥ P{''B''}. The last relationship states that knowing that the person has emphysema increases the likelihood that he will have cancer. The reason for this is that having the information that the person has emphysema increases the likelihood that the person is a smoker, thus indirectly increasing the likelihood that the person will have cancer. However, we would not want to conclude that having emphysema causes cancer. Thus, we need additional conditions such as temporal relationship of ''A'' to ''B'' and a rational explanation as to the mechanism of action. It is hard to quantify this last requirement and thus different authors prefer somewhat different definitions.{{citation needed|date=April 2016}}