I’ve seen people criticize my word nominalist ‘definition of coercion’ and suggest the TCS ‘definition of coercion as the correct one. The TCS definition of coercion is as follows:
By “coercion” we mean:
1. the psychological state of enacting one idea or impulse while a conflicting impulse is still active in one’s mind.
This leads to some subsidiary meanings:
2. the action of intentionally or recklessly placing someone in a state of enacting one theory while a rival theory is still active in the person’s mind;
3. behavior that is intended, or likely, to do this.
Compare this definition to mine:
Coercion is the word we use to describe the feelings we have when the mere existence of someone else with a different idea than me acts in a way that impacts me in ways I do not enjoy.
But I conjecture that these two definitions are functionally one and the same. That conjecture is equivalent to a universal statement saying “there are no cases where the TCS definition of coercion identifies a situation as coercive that my definition doesn’t also make the same identification and vice versa.”
Now that this has been phrased as a universal statement, this makes my claim testable in the Popperian sense because it is now refutable. My claim that the two definitions are identical can be easily refuted now by simply showing me an example of where one of the two definitions identifies a coercive situation that the other doesn’t. If you can’t find such an example then my conjecture is the best explanation available to you and it’s rational for you to adopt it. (And failure to adopt it is irrational.)
Let’s try this out quickly. I had someone point out to me that my definition of coercion would mean that if I don’t like you and want you to leave my presence while in a public place – where you have a legal right to be – and you refuse to leave that you are being coercive to me.  And I agree! My definition does imply that. But so does the TCS definition! After all, no matter what my reason for wanting you to leave is (perhaps you make me feel uncomfortable) if you refuse to do so you put me into a psychological state where the enacting of your idea (you refuse to leave the public place) is creating a conflicting impulse in my mind (I want you to leave and you won’t) is still active in my mind. So your refusal to leave when I want you to (even though you have a right to be there) is a case of you being coercive to me in the TCS sense.
I challenge those that think these two definitions are different to try to find even a single counter example.
Why the TCS Definition of Coercion is Intentionally Subjective
Actually, this isn’t a bad thing. I suspect Sarah Fitz-Claridge chose this definition for coercion precisely because it was equivalent to saying “anything that makes a child feel bad is coercion.” In other words, I believe she likely intentionally chose to define coercion in a subjective rather than objective way. (Consistent, in my mind, with how people normally use the term!) 
Young children are in a uniquely coercive state of affairs due to their dependence on their parents for property and physical well-being. The TCS definition of “coercion” was meant to drive home this fact by making it clear that even trying too hard to persuade a child against their will (by say, yelling at them or for that matter, just pressuring them) should be considered coercive. So the fact that these two definitions are identical is, I suspect, a feature not a bug.
Should Libertarians Use the TCS Definition of “Coercion”?
Does the fact that the TCS definition of coercion is subjective have consequences to libertarian political theory? Probably not. Libertarians do not try to define ‘coercion’ the TCS way. Their version of coercion seems to map to whether or not someone has entered into a contract. For example, when I’ve asked libertarians in the past if a boss yelling at an employee — or threatening to fire them — for not doing what they were asked was ‘coercive’ I was told in no uncertain terms that there was no coercion there because the employee freely entered into a contract to be employed and can leave any time they wish.
Yet this example clearly violates the TCS definition of ‘coercion’ because the employee will now be “plac[ed]… in a state of enacting one theory [i.e. the boss’] while a rival theory [i.e. the employee’s] is still active in the person’s mind” unless he’s prepared to go searching for a new job. So this example is not coercion in the libertarian sense but is in the TCS sense! Since we now have an example of where the two draw differing conclusions, we can now know that they must be defining ‘coercion’ differently.
So the libertarian version of ‘coercion’ is a different understanding of ‘coercion’ than the TCS version because it attempts (perhaps unsuccessfully) to bring about a more objective definition of what legally counts as ‘coercion’ that is a higher bar than merely feeling like you were pressured into something you didn’t agree with.
 Under my and the TCS definition of ‘coercion’ we are actually both being ‘coercive’ to each other. This is an example of what I’ve called “simultaneous coercion.” People often feel coerced because someone wants to live their life differently than they want to. In this case, I don’t want to see you when I’m in a public place and you want to be in that public place. We both have different operating ideas about how we want to live our life that conflict. However, it is not the case that these two ideas are equally coercive. As Popper explained, we have to rely on our traditions to figure out which of these two conflicting desires should count as more coercive than the other.
It’s tempting here to suggest that me wanting you to leave a place you have a right to be in makes my desire more coercive than yours. But that may not be the case. For example, perhaps you have a history of harassing me and I have a restraining order on you. A court has now determined that while you have a right to be in that public place, you don’t if I’m there. It is impossible to resolve which desire is the ‘least coercive’ without a full account of why we feel the way we do and our past history leading up to that point. This can’t be decided by making a one-size-fits-all rule. The specifics of the situation must be taken into consideration to determine who is being the least coercive given the circumstance.
 I got some questions on what I meant by ‘subjective.’ I’m using it in the common scientific usage to refer to anything related to subjective experience, i.e. qualia/feelings etc. I’m saying quite literally the TCS defines coercion as ‘anything that makes the child feel coerced is to be considered coercion.’ Look over the definition carefully and you’ll see that this is the case. Even just trying too hard to persuade a child (to the point where they feel pressured) is considered coercion under the TCS definition. This isn’t a criticism of the TCS definition! If I understand correctly, TCS is about caring about such subjective feelings in a child. So this is probably by design that they chose to define it this way.