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Causal Fallacies

It is common for arguments to conclude that one thing causes another. But the relation between cause and effect is a complex one. It is easy to make a mistake. In general, we say that a cause C is the cause of an effect E if and only if: (1) Generally, if C occurs, then E will occur, and (2) Generally, if C does not occur, then E will not occur either. We say “generally” because there are always exceptions. For example, we say that striking the match causes the match to light, because: (i) Generally, when the match is struck, it lights (except when the match is dunked in water), and, (ii) generally, when the match is not struck, it does not light (except when it is lit with a blowtorch). Many writers also require that a causal statement be supported with a natural law. For example, the statement that “striking the match causes it to light” is supported by the principle that “friction produces heat, and heat produces fire”.


Causal fallacies as causal claims unsupported by premises…

‘False cause’ is a term covering a variety of logical sins. Most simply, it means confusing a cause with an effect. But it may also mean offering an immediate causal explanation for an event without considering alternatives. Another variant is post hoc ergo propter hoc (after this, therefore because of this — often abbreviated post hoc), in which a causal relationship is inferred merely from the temporal proximity of two or more events. What is common to all false-cause fallacies is that their conclusions are causal claims which are inadequately supported by their premises.

Nolt, Rohatyn, & Varzi, Schaum’s Outline of Theory and Problems of Logic, p. 210.

On Causa Essendi vs. Causa Cognoscendi

In order to keep us from falling under the power of these fallacies, Logic calls our attention to two important distinctions. There is the distinction between the Causa Essendi and the Causa Cognoscendi. The former is the objective cause in the powers of nature or of God; the latter, the facts or means by which we come to know the objective cause of the occurrence. The two are often confounded by much the same language being employed by us to denote them. Thus we speak of the ground being wet because it has rained; and of its having been rain because the ground is wet. It is evident that the Causa Cognoscendi is often an effect indicating the Causa Essendi; thus the melting of snow may be a proof or a sign of the rise of temperature which has made the snow to melt. Of very much the same character is the distinction between Reason and Cause; the Reason being that which brings conviction to us, and the Cause that which produces the phenomenon. The increase of temperature is the cause of the melting of the snow, but the melting of the snow as being an effect may, on being contemplated by us, be the means of revealing the action of the Cause. 

On overlooking alternative, possible causes…

This mistake, of confounding temporal sequence or coexistence of facts with causality,
is not quite the same as confounding a temporal sequence or coexistence of judgments in the mind with the logical consequence of conclusion from premises. But little ambiguity can arise from giving the name of false cause to the inductive fallacy in question. And this mistake of confounding mere sequence or coexistence with causality or consequence is one of the many modes of the fallacy of Illicit generalization which will be examined presently. … In induction we pass from observation of particular facts, through analogy, and hypothesis, to the discovery and verification of general laws. Here, then, the first possible source of error will be Imperfect Observation, and the fallacy may be either negative or positive in character. NON-OBSERVATION is the fallacy of overlooking something that ought to have been observed. The function of observation is to select and isolate the facts from which we hope to bring to light some causal law. Hence we may either fail to notice instances pertinent to the kind of fact we are investigating, or fail to notice influences that are really operative in the instances actually observed.

Coffey, The Science of Logic, Vol. 2, pp. 328-9.