What is this fallacy?

"I threw a ball onto the roof. Which way did gravity pull it? Well obviously because the ball started on the ground level and ended up on the roof then gravity must have pulled the ball upward."

The error is that it ignores rate of change and misunderstands acceleration. It seems to assume that gravity changes the position directly, when in fact gravity changes the rate of change of the position.

The real world example I see a lot in politics goes like "Politician X's policy on stopping Y was a failure because Y increased over X's term" when in reality Y was accelerating downward (just like the ball on the roof). In this case, the fallacy seems related to cherry picking data because it only looks at the start and end points of Y and ignores the rate of change differences. Is there a specific name for this fallacy?

  • 2
    These two examples are not of a kind. The first is not a fallacy, although some call it Aristotle's fallacy because in his physics velocity was proportional to the force. Fallacies are mistakes in reasoning, getting one's physics wrong is not a mistake in reasoning, it is a factual mistake. The second one turns on criteria of success and failure. If the goal was to decrease Y the policy was a failure, the downward acceleration fell short, so it is not necessarily a fallacy either. – Conifold Aug 14 '20 at 21:21
  • Not sure I grasp the first example. Seems like the analogy is more complex than the problem. Don't you just mean absolute "growth" versus relative "growth." We can claim accurately that "unemployment grew" during X's term, when it grew at a far slower rate "relative" to its prior growth rate. Conversely, we can say X "added a historic number jobs during her term," when X actually added a historically low number of jobs, relative to population. It is a widespread bit of political sophistry, and perhaps it could be restated as a fallacy, a faulty identification of two types of measurement? – Nelson Alexander Aug 14 '20 at 22:40

Most generally, I think this would be a case of the post hoc and causal oversimplification fallacies.

'Policy A was implemented and then Y increased, therefore policy A caused Y's increase' fallaciously infers that Y's increase was caused by the policy's implementation with the insufficient justification of causal order (increase occurred after implementation), which is the post hoc fallacy, and neglects the existence of at least one other contributing cause, which is causal oversimplification.

Similarly, '[Gravity exists and] the ball started at my hand height and moved to the roof height, therefore gravity moved it upwards' infers the ball's movement is due to gravity because gravity started existing before the ball was thrown (post hoc) and neglects the contributing cause of you throwing it (causal oversimplification).

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.