Simply saying something like "that stupid chair" is interpreting these things in human terms. People can be stupid; chairs cannot be "stupid".
Saying "that is a stupid horse" or saying that "that horse did that on purpose so I would fall off" is the same thing. You are attributing positive and negative human behaviors and intentions to an animal. The intentions of the horse are not the same as the intentions of a human. The intentions of a human may be based on things like spite, hate, envy, etc. as well as love, empathy or compassion. Intentions of a horse are based solely on its evolutionary characteristics. Horses have evolved as prey animals. They are always on alert and have a strong "flight" response to perceived threats and harms. That is why a horse is likely to shy or buck at the slightest thing like a shadow on the ground, or a bird, or a sound. It is in their nature to be ready to flee in the face of danger or the unknown. The underlying intention of this behavior has nothing to do with the rider; it has everything to do with its evolutionary survival mechanisms.
So how does one deal with this?
I have watched different people deal with this in different ways. One of the most common responses is to get angry and try to wrestle with the horse - pulling hard at the reins and kicking the horse (my daughter used to do this too). This may temporarily control the horse but what did this teach the horse? It taught the horse that it will be punished for doing something in which it has no control. It's the same as calling a dog that won't come. Once the dog finally comes, I see many people so angry that they beat the dog. What did that just teach the dog? It taught it that if it comes, it will be punished/abused. That is the complete opposite of the lesson that you want to teach your dog. This is also the complete opposite of the lesson that you want to teach your horse. For the dog, regardless of how angry you are, when it finally comes, you need to be full of praise and positive reinforcement (such as treats). This teaches the dog that to come is a good thing to be rewarded. That will make the dog more eager to come the next time. For the horse, it's the same thing. You need to reassure the horse that it has nothing to worry about. You need to continue as if nothing happened. By not acknowledging the fear response, you teach the horse that it can trust you. And trust is a much more permanent form of control than is anger.
Remember, It is not a "stupid" horse or a "bad" horse for doing this. It is just a horse, doing what horses do. To say anything else is to attach human characteristics and intent to its behavior - anthropomorphism.
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