Cum Hoc, Ergo Propter HocTranslation: "With this, therefore because of this", Latin
Type: Non Causa Pro Causa
Near-perfect correlations exist between the death rate in Hyderabad, India, from 1911 to 1919, and variations in the membership of the International Association of Machinists during the same period. Nobody seriously believes that there is anything more than a coincidence in that odd and insignificant fact.
Source: David Hackett Fischer, Historians' Fallacies: Toward a Logic of Historical Thought (Harper & Row, 1970), pp. 168-169.
Charging that welfare causes child poverty, [Gary Bauer] cites a study showing that "the highest increases in the rate of child poverty in recent years have occurred in those states which pay the highest welfare benefits. The lowest increasesor actual decreasesin child poverty have occurred in states which restrain the level of AFDC payments."
The bigger a child's shoe size, the better the child's handwriting.
Cum Hoc is the fallacy committed when one jumps to a conclusion about causation based on a correlation between two events, or types of event, which occur simultaneously. In order to avoid this fallacy, one needs to rule out other possible explanations for the correlation:
David Hackett Fischer, Historians' Fallacies: Toward a Logic of Historical Thought (Harper & Row, 1970), pp. 167-169.
Bauer uses specious statistical studies to discredit the welfare system. But this study by two Ohio State University sociologists overlooked the fact that median income declined or was flat in the ten states where welfare costs and child poverty rose, while income rose substantially in nine of the ten states where welfare payments and poverty showed the least increase. The data showed that economic decline caused an increase in both welfare and child poverty.
Source: John B. Judis, "The Mouse That Roars", The New Republic, August 3rd, 1987, p. 25.