Post hoc ergo propter hoc

From Wikipedia

Post hoc ergo propter hoc (Latin: “after this, therefore because of this”) is a logical fallacy (of the questionable cause variety) that states “Since event Y followed event X, event Y must have been caused by event X.” It is often shortened to simply post hoc fallacy. It is subtly different from the fallacy cum hoc ergo propter hoc (“with this, therefore because of this”), in which two things or events occur simultaneously or the chronological ordering is insignificant or unknown. Post hoc is a particularly tempting error because temporal sequence appears to be integral to causality. The fallacy lies in coming to a conclusion based solely on the order of events, rather than taking into account other factors that might rule out the connection.

he following is a simple example:

The rooster crows immediately before sunrise;
therefore the rooster causes the sun to rise.


The form of the post hoc fallacy can be expressed as follows:

  • A occurred, then B occurred.
  • Therefore, A caused B.

When B is undesirable, this pattern is often extended to the inverse:
Avoiding A will prevent B.


  • “I can’t help thinking that you are the cause of this problem; we never had any problem with the furnace until you moved into the apartment.” The manager of the apartment house, on no stated grounds other than the temporal priority of the new tenant’s occupancy, holds that the tenant’s presence has some causal relationship to the furnace’s becoming faulty.
  • The Brazilian footballer Pelé is said to have blamed a dip in his playing performance on having given a fan a specific playing shirt; after getting the shirt back, his performance recovered. Thus, he said, the loss of the shirt was the reason for his dip, and its return was the cause of his recovery. (It was later discovered that the shirt that was returned to him was not, in fact, the one he had given up.)

2 Replies to “Post hoc ergo propter hoc”

    1. One important issue with ‘post hoc’ involves the interpretation of EKG potentials called the P, QRS, and T waves, which is based on cell action potentials. Cells depolarize and repolarize during the heartbeat.

      Doctors teach that cardiac cell action potentials generate EKG waves. Firtst, atrial cells depolarize and cause P waves. Next, ventricular cells depolarize and produce QRS waves.

      Moreover, cardiologist teach that repolarization generates electric potentials. Thus, ventricular cell repolarize and generate T waves. This theory requires that the ventricle muscle cells have a massively prolonged time for depolarization, about 100 times longer than other muscle cell action potential times.

      Research by Findl and Kurtz in 1977 observed that motion of electrolytes from pulsed blood flow from artificial mammalian hearts generates EKG like signals.

      In other words, blood flow generates EKG potentials, not cell depolarization or repolarization.

      Thus, atrial contractions generate blood flow, which produces P waves. Next, ventricular contractions generate blood flow, which produces QRS waves. Finally, contractions of the aorta and pulmonary artery generate pulsed blood flow motion, which produces T waves.

      Electrical and neurological events move FAST, near the speed of light, which blurs the evidence and leads to ‘post hoc’ mistakes.

      ECG details need to be split into tiny pieces that make sense. ECG blood flow potentials makes more sense than cell depolarization / repolarization potentials.

Leave a Reply

Your email address will not be published. Required fields are marked *

Time limit is exhausted. Please reload the CAPTCHA.