Why would someone who is already in pain wish to inflict it upon others?

The answer you are looking for is already in the question. Sometimes (in fact, more often than not), people hurt others exactly because they are in pain themselves. If pain is all they know, pain is the only thing they can offer to others. By hurting others people may experience a perception of fairness ("if everybody around is hurting, then my own pain is somewhat fair"), or even relief ("if I hurt someone else, maybe they will hurt more than me, and that means that my pain may not be as bad in comparison"). These processes tend to happen subconsciously, meaning that people often do not intend any harm to others, and when asked why they did, they truly may not know the answer. This means that often people will hurt others without such intent per se, but rather in subconscious efforts to relieve their own pain.

Some people feel that if they are in pain others should also be in pain so that they don't suffer alone. Also, a sense of "justice": "if I am not fine it is not fair that someone else is fine". Some may do it because it helps them feel relief. Some have a sense of revenge, and think that the causes or worse need of the pain deserve to suffer as well and they take the matter into their own hands. Anger can make this easier. But, in general, it is a lack of empathy towards the victim, and a sense that something will be gained or a loss will be prevented by doing that.

We can't predict the intentions of others. Sometimes, we do things we can't account for. We're swept up in the pain and the easiest form of relief is when others experience it, too. No one's perfect. Remember, be kind. Be understanding in that this person may be experiencing some issues that have caused them to project this hurt onto others. At this state, the best rule of thumb is to give them space. Remind them you're here and when they're ready, you could talk about these issues together. I find distance can be a good thing when you're in a situation such a this, and the best initiative is to be supportive, but not engage until they're ready to discuss it without the intention of hurting.

This is a really, really, really good question.. You would think that someone who is in pain would only wish to empathize with others who are also in pain, and certainly not be the cause of it for anyone else. But the truth is, some people use it as a way of coping with their own pain. They take their anger and pain out on innocent people, because they feel like it gives them power and control over pain, in general. However, it’s still not justifiable to hurt someone else just because you’re hurting. You need to deal with it in a different way. And if you’re the victim, you need to immediately get help.

I believe that the answer depends on the personality of the individual who is projecting their pain. Some have vindictive streaks, so to speak. Others are just trying to get the pain outside of themselves. Sometimes it is a combination. E.g. in my own case, I believe I am the recipient of hurtful projection because my son ended his marriage and because he is the father of the children, he cannot be the target of the wife's anger because at least to the degree that they continue parenting together they must remain amicable. It hurts me a lot but I have chosen not to engage in the drama and have long since let her known that she is still loved and that I understand to what extent I can what she's going through. I choose not to acknowledge any of the digs against my son that she sends my way. I ignore them completely and when she has expended all her anger, and she realizes I'm not going to bite on her efforts to pull me in, I assume she'll stop. We shall see. But, certainly there is no purpose whatever in me retaliating or insinuating myself in her drama. She knows I love her and loving her includes loving this aspect of her. She is a wonderful mother to my grandsons. I am grateful for that enough to ignore the other.

It's an interesting phenomenon. In short, they may not have found a way to cope with the pain yet, so they lash out against their environment that they believe is causing them to feel pain. They may feel things are closing in around them and that they have to push back to give themselves space. They may not necessarily want to cause harm to those close to them, but they need to release it somehow and if they don't already have a set process to do so, they will be lead by human nature and release it quickly and haphazardly at whatever or whoever is closest.

There are many different reasons why someone in pain might wish to inflict it upon others. Inflicting pain on someone else might give them the sense of control. They may not be able to control their level of pain, and feeling out of control can be terrifying, so it can help them to feel like they are in control of something at least. Making sure someone else is in pain can also show them they are not the only one suffering, as feeling alone can be awful. Also, sometimes, when a person is in so much pain, they want others to feel the same way they do. They want others to experience the hurt, the pain, the difficult that they feel. A quote I have heard that I feel describes this very well is “Hurt people hurt people.”

Because they think that it will help them feel better to inflict pain on others. It's kind of like bullies. Bullies usually are dissatisfied with their own lives, so they try to make others lives miserable. It's just human nature to want to inflict pain on others when we are in pain. It's just a part of who we are. Bullies usually have a problem going on at home, or they are being abused. It makes them feel better about their own miserable lives if they make other people's lives miserable. It's just the way humans are. It's a part of human nature.

This is a classic symptom of bullying. We feel in pain and hate being in this position, wish to hit out at something to express that pain. We also dislike ourselves and feel weak. Seeing someone else like us reminds us of what we are like. We see that pain and that weakness and want to hit out at it. If we can realise the pain we are feeling, and understand it, we can break the cycle. This is also a good way to deal with bullies - they are feeling pain and weak, and if we can understand that we can help them heal too.

Sometimes those who are hurt are angry. Angry souls don't always wish to inflict pain upon others, but sometimes, we do it out of habit and fear.. it's a defense mechanism. We want to be alone, it's the way the human mind works. It's a strange motive, yes, but it happens to the best of us! When someone is in pain, be careful and cautious. You don't want to harm them in any way.