How can I know if a snickerdoodle cookie tastes good?
I can put it in my mouth. Chew it down. And swallow it up.
Or I can smell it. But that only gives me a hint at how it might taste. I’ll admit that fresh snickerdoodle cookies smell nice. But I’ll never admit that they taste as good as they smell.
So how can you and I know if we’re talking about the same kind of cookie? Well, it helps to use the same measurements. But we can’t always use the same exact measurements. And so it helps to use measurements that at least point in the same direction.
Your sense of taste and my sense of taste are different. According to my tongue, snickerdoodle cookies are bad. According to your tongue, they’re great. And that’s okay, we can have a reasonable snickerdoodle disagreement.
But at least we can agree that your tongue and my tongue are measuring the same thing.