"How do you know that?"

Decisions. Trust. Regrets. All depend on your judgment of certainty: Your basis for choosing path A over path B, and all consequences of that choice. There's no such thing as avoiding risk when you realize that even a non-decision is, indeed, a decision (you've decided to risk a random outcome).

Take the example of driving your car, coming upon a stoplight. You're approaching the 4-way intersection at 45 MPH, and there's no one stopped at the lights for street that crosses yours.

You proceed through, without slowing. Right?

But how do you know that the stoplights are working properly for all lanes? How do you know that big truck just approaching will actually stop, even if the light in his direction is red?

Probability and experience. However you see it.

This is the section of the website where I'm putting my key philosophical bent. And, in keeping with my effort to "integrate" my myriad life interests here, you may reasonably ask how a guy so fascinated with time pieces could at the same time wrestle to widen the parameters of functional tolerances.