Inflationary terms! You see them everywhere. And for those who actually know and care about the subject matter they can be very frustrating. These terms are notorious for being used in contexts where:
- They are only loosely applicable at best.
- There exists a better word that is more specific.
- The topic has a far bias.
The problem is not that these words are meaningless in their original form, nor that you shouldn't ever use them. The problem is that they often get used in stupid ways that make them much less meaningful. By that I mean, less useful for keeping a focus on the topic and understanding what the person is really talking about.
For example, terms like Nanotech (or worse, "Nanobot") do apply in a certain loose sense to several kinds of chemistry and biological innovations that are currently in vogue. Nonetheless, each time the term is used to refer to these things it makes it much harder to know if you are referring to Drexlerian Mechanosynthesis. Hint: If you get your grant money by convincing someone you are working on one thing whereas you are really working on something completely different, that's fraud.
Similarly, Cryogenics is the science of keeping things really cold. And of course Cryonics is a form of that. But saying "Cryogenics" when you really mean exactly Cryonics is an incredibly harmful practice which actual Cryonicists generally avoid. Most people who work in Cryogenics have nothing to do with Cryonics, and this kind of confusion in popular culture has apparently engendered animosity towards Cryonics among Cryogenics specialists.
Recently I fell prey to something like this with respect to the term "Rational". I wanted to know in general terms what the best programming language for a newbie would be and why. I wanted some in depth analysis, from a group I trust to do so. (And I wasn't disappointed -- we have some very knowledgeable programmers whose opinions were most helpful to me.) However the reaction of some lesswrongers to the title I initially chose for the post was distinctly negative. The title was "Most rational programming language?"
After thinking about it for a while I realized what the problem was: This way of using the term, despite being more or less valid, makes the term less meaningful in the long run. And I don't want to be the person who makes Rational a less meaningful word. Nobody here wants that to happen. Thus it would have been better to use a term such as "Best" or "Most optimal" instead.
Another example that comes to mind is when people (usually outsiders) refer to Transhumanism, Bayeseanism, the Singularity, or even skepticism, as a "Faith" or "Belief". Well yeah, trivially, if you are willing to stretch that word to its broadest possible meaning you can feel free to apply it to such as us. But... for crying out loud! What meaning does the word have if Faith is something absolutely everyone has? We're really referring to something like "Confidence" here.
Then there's Evolution. Is Transhumanism really about the next stage in human Evolution? Perhaps in a certain loose sense it is -- but let's not lose sight of the mutilation of the language (and consequent noise-to-signal increase) that occurs when you say such a thing. Human Evolution is an existing scientific specialty with absolutely zilch to do with cybernetic body modification or genetic engineering, and everything to do with the effects of natural selection and mutation on the development of humans in the past.
Co-opting terms isn't always bad. If you are brand-new to a topic, seeing an analogy to something with which you are already familiar may reduce the inferential distance and help you click the idea in your brain. But this gets more hazardous the closer the terms actually are in meaning. Distant terms are safer -- when I say "Avoid inflationary use of terms" you can instantly see that I'm definitely not talking about money, nor rubber objects with compressed air inside of them, but about words and phrases.
On the other hand with such things as Rational versus Optimal, we're taking two surface-level-similar words and blurring them in such a way that one cannot meaningfully talk about either without accidentally importing baggage from the other. Rational is more suitable for use in contrast with clear examples of irrationality -- cognitive biases, for example, or drug addiction, and is a rather unabashedly idealistic term. Optimal on the other hand doesn't so much require specific contrast because pretty much everything is suboptimal by default to some degree or another -- optimizing is understood as an ongoing and very relativistic process.
To sum up: Avoid making words cheaper and less effective for their specialized tasks. Don't use them for things where a better and more appropriate term exists. As your brain gets used to an idea, be prepared to discard old terms you have co-opted from other domains that were really just useful placeholders to get you started. Specialized jargon exists for a reason!