In article , "Leon" wrote:
[...]
"And *I* wouldn't buy one because when the time comes that my common sense,
agility, and attention to safety factors are so badly deteriorated that I
feel the need for the device I will discontinue using a table saw."

So how will you know when your common sense is gone?

Exactly so. Well said, Leon. You hit the nail on the head. When your common
sense is gone, how will you know -- how *can* you know -- when your common
sense is gone?

My wife and I have an example of that right in our own household. Her parents,
both in their late 80s, have been living with us for nearly two years now.
Unhappily, my MIL is in the middle stages of Alzheimer's disease (or some
similar progressive dementia), which makes it completely impossible for her to
drive a car safely -- and also prevents her from realizing that. She can't see
either (can't even make out the big E on the chart), and she also can't
understand why *that* should stop her from driving.