Since scientific laws are based on a limited number of observations, we can never be sure that they are true.

We can never be so 100% sure of anything, because nothing is ever certain. If you drop an object, it will most likely hit the ground every single time, and people have observed this for as long as the earth has been around. It has been recorded many many times, and everyone can hypothesize,  that if you drop a object, it will hit the ground. And after heavy research scientists have concluded that this is due to gravity, and they are most likely certain that every single time the object will fall and hit the ground. But what if all of a sudden the earth’s gravity faltered, or shifted, making that object float away. Now every one of those tests, after thousands of years of thinking that every single time we drop an object it will hit the ground, it was all proven wrong. This one incident has changed history, and now, people are not sure that if they drop an object, it will hit the ground. Everything is limited, and never proven true, even though you test something a million times, it only takes one time to change it.