What do you guys think of UFO's?

[Your Computer]

It IS practical. We use it in everything and it works.

While it is arrogant to say that we have a perfect understanding, you have yet to provide a viable alternative.

We have to work within the boundaries of what we understand otherwise we are making unfounded assumptions. That's how we used to work, we don't do that anymore.

I never said it isn't practical. However, practical is relative. I don't have to provide a viable alternative to any scientific theory, law or similar; that kind of burden of proof is not on me. And why should we seek to understand what we already understand? You have to work from unfounded assumptions in order to progress and from things that we don't yet understand. We do indeed still work like that. Intuition and insight breed theories. Whether unfounded or not, theories are still widely put into practice today.