The word redefine didn't enter into English usage until the 1840s. Today, however, it's use is ubiquitous. There seems to be a common sentiment that everything must be redefined, not simply reformulated or resourced. If you think about it, the idea of redefining something is very odd. This is because we naturally understand the definition of a thing to be something we discover, not something we constitute. St. Thomas Aquinas, for example, uses at least two definitions for a person – an individual substance of a rational nature, and a master of one's self. Both definitions are equally valid descriptive of different aspects of personhood. However, neither of these definitions negate or conflict with the other; they're simply precise descriptions of an object considered from different angles for the sake of analysis. This is radically different than today's trend of redefinition.
Oddly, the current business trend of rebranding is closer to the traditional method of defining than the contemporary method of redefining. When done well, rebranding capitalizes on the actual things that a business does and excels at. When done poorly, it tries to capture what a business would like to do well. The difference is subtle, but it's one that can lead to real world successes and failures. The former describes a reality, the latter describes a fantasy.
This gets at the heart of the problem with redefining words. Words, i.e., definitions, are supposed to accurately describe things the way they actually exist regardless of how we might want them to be. Redefinition tends to describe things the way we wish them to be regardless of how they actually exist. Essentially it's the difference between accepting or rejecting the objective reality of a thing. What's worse is that when we redefine something we expect it to bend to our new definition. It's like defining light as darkness, ice cream, or cowboy boots.
The great danger with this is that it's at least a tacit denial of the intelligibility of reality. As we continue to redefine things according to our subjective whims we do violence to the ground upon which human knowledge stands. Words lose their meaning because they no longer signify real things. If this trend continues each one of us will eventually end up with our own private language game. We are already seeing the practical implications of this trend in the widening polarity of contemporary politics. Debates have devolved into shouting matches where opponents are frequently talking past one another. Political opponents often lack a common language, so to speak. The contemporary marriage debate is a perfect examples of how the meaning of words have lost any ground in a commonly held notion of reality. And, this is, in fact, what is at stake. In the end, the question is about the nature of reality. Is it something we must accept as given, or something we constitute.
The assault on language is one of the most troubling aspects of modernism. It's an attack on the reality of the world, and hence on the intelligibility of the world. Really, take some time to reflect upon the very serious ramifications of this phenomenon.
They are all around us. And, they aren't pleasant.