The questionable cause—also known as causal fallacy, false cause, or non causa pro causa ("non-cause for cause" in Latin)—is a category of informal fallacies in which the cause or causes is/are incorrectly identified. In other words, it is a fallacy of reaching a conclusion that one thing caused another, simply because they are regularly associated.

Questionable cause can be logically reduced to: "A is regularly associated with B; therefore, A causes B."^[1]

For example: "Every time I score an A on the test its a sunny day. Therefore the sunny day causes me to score well on the test." Here is the example the two events may coincide or correlate, but have no causal connection.^[2]

Fallacies of questionable cause include:

• Circular cause and consequence^{[citation needed]}
• Correlation implies causation (cum hoc, ergo propter hoc)
  • Third-cause fallacy
  • Wrong direction
• Fallacy of the single cause
• Post hoc ergo propter hoc
• Regression fallacy
• Texas sharpshooter fallacy
• Jumping to conclusions
• Association fallacy
• Magical thinking