what are you saying your observation is
I observe that the reading on the scale is "51g," as I said in the first place.
do you consider it true or false?
Yes. True.
what do you consider "known" before the observation?
All kinds of things. In the case with a standard 50g callibration weight, that includes the mass of the weight.
This is getting stuck in the morass of trying to distinguish between observations and interpretations. I don't particularly want to discuss the philosophy of qualia.
My point is much simpler. It's quite common for data points which everyone calls "observations" to be false. Trying to fix that problem is called cleaning the data and can be a huge hassle. In practical terms, if you get a database of observations you cannot assume that all of them are true.
Another month, another rationality quotes thread. The rules are: