Many of us are quite familiar with the OpenClosedPrinciple (one of many OoDesignPrinciples). BertrandMeyer first coined it in the first edition of ObjectOrientedSoftwareConstruction as follows:

	 :	A class should be open for extension, but closed for modification.

However, sometimes something similar applies to people as well. Call it an
AntiPattern if you like, but sometimes it is the case that someone suffers from what I call the OpenClosedMindPrinciple [ that should be parsed as (Open(Closed-Mind)Principle) ] :

	 :	Someone's mind is open for extension [of their own ideas], but closed for modification.

In fact, some would suggest that BertrandMeyer has exhibited this behavior himself when it comes to discussing Eiffel and other things.

We've probably all fallen victim to the OpenClosedMindPrinciple at some time or another (I know I certainly have). You can be discussing something with someone and then suddenly rather than consider changing their mind about something, they shift into half-duplex mode (dispensing considerable output but accepting no further input ;-).

How do we stop this from happening to us, or else catch ourselves when it does? How should you handle it when it happens with a co-worker? a supervisor? a friend or a family member?

	 :	''Is not listening always necessarily a bad thing? Suppose someone is trying to convince you that you don't exist, or that you should commit a murder? Suppose somebody is reading the output of a RandomSentenceGenerator? Should you listen to them? Are you obliged to consider that they might be "right?"''

	 :	''Of course, there's no obligation to convince them of your view, either... if you have an irreconcilable difference with someone, the best thing to do is either change the subject or shut up entirely... maybe something will happen that brings them around, or brings you around (if you're the one who's wrong, but then, that hardly ever happens :-), or that makes the whole point moot.''

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When I go HalfDuplex, i take it as a sign that i'm wanting to hear something going on in my head right now more than about the other mind. If i can't hear my message inside in a few seconds, i will probably arrange to get time away shortly, or at least inform the other person that i'm not usefully listening to them anymore. --JohnAbbe
(Well, when i'm FullDuplex inside i do that :-).

Of course the best strategy is to shift into the same mode before they do, and outtalk them.

Another really good strategy is to accept no further input from the person, on the grounds that their (or is it my) mind is closed. If possible, exclude them from further communication on topics that interest me.

''Fear not Ron, I wasnt thinking of you in particular when I created this page. The stimulus for this one was much closer to home. --BradAppleton''

When I find myself doing that to someone, I take it as a sign that I was becoming convinced against my will and needed to protect myself.

When I'm sure my colleague hasn't understood what I've said before disagreeing or embellishing it, I ask them to explain my idea to me. Usually they won't do that, just garbling what I've said, I often feel intentionally, so as to support their own idea.

Sometimes I start by explaining their idea to them: "Here's what i think you are saying ...", doing it as honestly as I can. That sometimes gets them to do the same for me.

If you're physically present, it helps to come over to their side of the table. Writing on cards helps because you both touch them.  --RonJeffries

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Interesting.  Try this for a commentary:  OnlySayThingsThatCanBeHeard.

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It's too easy to fall into this mode, especially when you're near one of your favourite HobbyHorse''''''s. If only the other participants will get out of your way so you can go out for a gallop! Maybe you should mow them down!

A good discipline to adopt to prevent this in yourself is to let the other person do the work. To continue the analogy, say you're about to thunder away churning the mud with your hooves when your riding partner dismounts to smell the flowers. What do you do?

Stop and wait. If the flowers look like they'd smell very sweet, you might dismount too. If they're lilacs, though, and you hate lilacs, just sit and feed an apple to your horse. Your riding partner will soon suggest a canter just because that seems like the obvious thing to do. And then you're off!

Some riding partners want to stop and smell a lot of flowers. Just you keep a big bag of apples handy. --PeterMerel