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OCD and the Need for Certainty

Your OCD may stem from a false need for certainty. What can you do about it?

Key points

  • There are two types of OCD: Moral and existential, both of which stem from a felt need for certainty expressed as a demand.
  • The felt need not to do bad things is deceptive; human actions are never certain by any reasonable definition of the latter term.
  • Overcoming this bogus felt need means (cognitively and behaviorally) embracing possibility, not certainty.
Impossible Dice Triangle Optical Illusion" by The Lex Talionis is licensed under CC BY-ND 2.0
Source: Impossible Dice Triangle Optical Illusion" by The Lex Talionis is licensed under CC BY-ND 2.0

OCD Thinking

There are, in general, two types of obsessions that can occur in obsessive-compulsive disorder:

  1. Moral
  2. Existential

In moral obsessions, the person imagines herself doing something she thinks would be extremely (morally) bad and ruminates about it.

In existential obsessions, the person imagines something bad happening to himself or a loved one, for example, getting sick and dying, and ruminates about it (Cohen, 2021). While this post examines the thought process embedded in moral obsessions, the logic in existential obsessions is similar. In both cases, the genesis of the obsession is a demand for certainty.

For example, suppose you think:

  1. I must be certain that I would not stab my partner with this steak knife.
  2. But I am imagining myself doing it and it almost feels like I’m going to really do it!
  3. I’s possible I’m going to really do it!
  4. But what kind of monster would do such a horrible thing!
  5. I can’t stop thinking about it until I can be certain I wouldn’t do it!

The above set of premises displays the emotional reasoning involved in moral obsessions. This reasoning chain produces and sustains the intense anxiety experienced by the person with a moral obsession.

Notice that the process is generated by a demand for certainty (Premise 1). Here, the term “must” expresses a felt need for certainty. The term “certain” entails both knowledge and impossibility (Chisholm, 1957, p. 19). That is, in Premise 1 you are demanding that you know that you would not do such a thing and that it is impossible for you to be mistaken. This is an extremely strong sense of knowledge that many contemporary philosophers would argue is vacuous and is satisfied only by truisms like “All triangles are three-sided.”

In Premise 2, you imagine yourself doing this very act and even feeling an urge to do it.

In Premise 3, from the very fact that you imagine yourself doing it and it feels so real, you conclude that there’s a real possibility you might stab your partner with the steak knife. Clearly, this premise conflicts with Premise 1, which demands that it is impossible that you would do such a thing.

Given the latter possibility, in Premise 4, you then damn yourself by calling yourself a “monster.” Such damning language thus reinforces a lack of self-respect, which feeds a vicious cycle of rumination.

Consequently, in Premise 5 you conclude that you can’t stop yourself from ruminating about this demoralizing thought until you can somehow be certain you wouldn’t do it. However, every time you imagine yourself doing it, you only reinforce your lack of certainty (if you can imagine it, then it’s not logically impossible). You torment yourself in a vicious ruminative cycle ad nauseam with no way out.

There is indeed no way out so long as you hang on to inconsistent premises—1 and 3. On the one hand, in Premise I, you demand certainty. But in Premise 3 you make clear that you don’t have certainty. This is because your performing the action in question is not impossible.

The Meaning of Impossibility

But, let’s look even deeper at this curious logic. What does it mean to say that something is impossible?

One sense of impossibility is physical impossibility. This means contrary to the laws of physics. For example, it appears to be physically impossible for life to exist without a water source. It is not impossible in this sense for you to stab your partner with a steak knife, however. This is because humans do not uncommonly do such regrettable things. That’s exactly why there are criminal laws that proscribe them.

Another sense of impossibility is logical impossibility. This means logically contradictory or inconsistent. For example, it is impossible in this sense to draw a triangle that has four sides. You could not even imagine doing such a thing because triangles, by definition, only have three sides. However, stabbing your spouse with a steak knife is not impossible in this sense because you can easily imagine yourself doing it; and that’s exactly what you have done in the present scenario—imagine yourself doing it.

As demonstrated here, you have painted yourself into the proverbial corner by demanding that something be impossible that is not so, in either the physical or logical sense. For each time you imagine doing this act, you reaffirm its possibility, which then contradicts the demand that you be certain you wouldn’t do it—that is, that it be impossible that you would do it.

Your only rational way out is to give up your demand for certainty. It is plainly self-defeating to cling to a demand that you cannot possibly satisfy.

What, then, does it take to give up this unrealistic demand?

Getting Practical

In Cognitive-Behavioral Intervention for Self-Defeating Thoughts (Cohen, 2021), I discuss the construction of a cognitive-behavioral plan to overcome this demand and gain freedom from self-oppression. You need to learn to accept possibility rather than certainty as a condition of living in the everyday world. If you wish, you could redefine the latter term as "certain for practical purposes."

Indeed, humans make decisions every day by accepting conditions that are not certain, but we merely assume that they will stand the test of time. For example, it is not certain that the earth will support life in the near future (there is no contradiction in the earth ceasing to support life), but you still make future plans. With much less assurance that something won’t go awry, you drive or take public transportation, cross busy intersections, live in proximity to nuclear power plants, or other sources of potential harm. You assume that most people with whom you have social commerce (from your babysitter to your physician) are not rapists, murderers, or psychopaths even though, no matter how carefully you check them out, you cannot be certain of this. These are things, that for practical purposes, you simply assume are probable enough to act on.

You don’t need certainty to live as though you have it; and once you live as though you have it (and here comes the behaviorally therapeutic upside of doing so), you won’t even feel the need to obsess about not having it.

This means pushing yourself to go about your life without checking and rechecking your thinking ad nauseam. It means not locking up the knife or throwing it away but instead using it to cut steak. It means giving up any other meaningless ritual you have concocted to remediate your anxiety (for example, humming to drown out your thoughts). This means accepting that it is not impossible (logically or physically) for you to do bad things, even very bad things. You are flesh and blood and like all other contingent creatures in the universe are subject to an infinite range of possibilities—some bad and some very wonderful. This means embracing possibility, not certainty, as an inescapable part of life on earth.


Cohen, E.D. (2021). Cognitive behavioral interventions for self-defeating thoughts: Helping clients to overcome the tyranny of 'I Can't'. London: Routledge.

Chisholm, R.M. (1957). Perceiving: A philosophical study. Ithaca: Cornell U. Press.