Predictive Power

The most compelling argument in favor of any ideology or theory is its predictive power.

If an ideology makes a prediction and fails, this counts against its validity.

If an ideology makes no predictions that can be tested, its validity remains marginal as is must depend on other less conclusive methods of science.

If an ideology makes a successful prediction, this adds to the validity of the ideology.

As obvious as this is, there are those who attempt dismiss predictive power by actually claiming that predictive power is arbitrary and subjective. I recently exchanged over 14,000 e-mailed words with one individual in defense of the superiority of ideologies having predictive power, only to finally discover that he had not even the slightest notion about what predictive power is. He stated the following.

“Superior predictive power” is … like saying ok, we’re going to play a game, and the object of the game is to bounce the ball off the wall. We’ll play to 15, and when I bounce the ball off the wall, I score a point. Period. You don’t get a point when you bounce the ball off the wall. According to the rules, I always win, because I made up the rules.

I’m not joking. In a desperate attempt to dismiss the superiority of beliefs that successfully employ predictive power as a gauge of their validity, and to place them on the same level of validity as beliefs with no successful predictions, he apparently did not even take a cursory look at the clear explanation of predictive power in Wikipedia or in any other resource. Instead, he personally decides to define predictive power as arbitrary or subjective so that he can maintain the notion that rational thought has no superiority over his own ideology that is based on bald assertions and nonsense that is largely untestable.

Let’s take a look at the actual concept of predictive power by repurposing this individual’s example of a ball.

Let’s imagine there is a red spherical object on a table. Three brothers all have different theories about it’s composition.

  • Larry: “Its a tomato.”
  • Harry: “No, it’s a rock.”
  • Barry: “No, it a superball.”

Now, these brothers could….

  1. go around and around with stronger and stronger affirmations of their beliefs and emphasize that they “know” that it is what they believe it is
  2. or they could employ arguments from reason which do have some legitimacy such as why, after 4 weeks, the ball has not rotted as a tomato would, or why it is red since very few rocks are red
  3. or they could employ a practical test of the predictions that emerge as unavoidable corollaries of their respective claims.

Note very carefully that these claims are not arbitrary or subjective in any way. Let me repeat that. The predictions are not created by the claimants, but are logical implications of the claims. There is not the subjectivity that our friend suggested in the red quotation above about somehow making up the rules of predictability.
Let’s tease this out. Let’s introduce a little sister of the brothers (Mary) who picks up the red spherical object on the table, and raises her arm as if to toss it against the wall. Let’s have the brothers make predictions that must fall in line with their claims.

  • Larry: “It will splatter against the wall demonstrating its composition as a soft vegetable.”
  • Harry: “No, it will hit the wall hard, then drop to the floor as if having the composition a rock.”
  • Barry: “No, it will bounce off the wall back to Mary as would any superball.”

Are these predictions subjective, or are they objectively constrained by the implications of the claims? These predictions are independent of the claimants, and necessarily emerge from the nature of the claims. For Larry to claim that his “tomato” would rise into the air as a helium balloon would makes no sense, and this claim could be tagged nonsensical since the predicted behavior departs from the behaviors of tomatoes thrown against walls.

So Mary throws the red spherical object against the wall, and it bounces back into her hand. This lends a high degree of credibility to Barry’s theory, and close to eliminates the theories of his brothers. Barry’s theory is superior due to its ability to more accurately predict an outcome to a test using a criteria that is neither arbitrary nor subjective.

Can the brothers claim that the prediction was subjective? No.
Can the brothers claim that the prediction was arbitrary? No.
Can they claims that the test was unfair for some reason? No.
Each of their predictions was a direct corollary of their basic claims of the constitution of the red spherical object.
Does the explanation of predictive power in the red quote above even slightly resemble what predictive power actually is? No. This is an example of an extreme distortion of a concept that has clear explanations readily available for anyone serious about intellectual integrity. Let’s take a look at some of the explanations and examples out there.


Explanation: The predictive power of a scientific theory refers to its ability to generate testable predictions. Theories with strong predictive power are highly valued, because the predictions can often encourage the falsification of the theory. The concept of predictive power differs from explanatory and descriptive power (where phenomena that are already known are retrospectively explained by a given theory) in that it allows a prospective test of theoretical understanding.


In nearly every religion, the prophecies of their respective scriptures are posited as having enormous power to validate the religion. I agree with this. If the prophecies of a particular religion or individual seer clearly and consistently surpasses what is probable, I would be compelled to sit up and listen.

This concept of predictive power is huge. A single source of alleged truth could overturn all conventional sources in a short time, simply by providing more accurate predictions. This is a concept that scientists rightfully highly regard, but also non-scientist in our daily lives. If the implementation a particular political ideology leads to the success of the state, then we can consider that ideology superior (for that time and place). If the reports of the predictive power of Bernard Madoff had been true, his investors had every right (and obligation) to consider his theories of investment superior to others. If reports of fulfilled biblical prophecy were true, we would be rationally compelled to favor Christianity as a superior ideology. The weather man who most accurately predicts the weekend weather is justifiably the superior weatherman, and no one can claim his predictions follow a subjective criteria.

Return to the quote in red above. Is this portrayal of predictive power even remotely close to what predictive power actually is? This is the type of reasoning and distortion you’ll encounter by those adopting ideologies that are lacking in substance. It is a dishonest attempt to even the playing field by misrepresenting predictive power as impotent. It is not. It is the primary test of superior validity for any claim.

Other Examples:

Other Resources:


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