§265

Wittgenstein: Philosophical Investigations 

§265 Let us imagine a table (something like a dictionary) that exists only in our imagination. A dictionary can be used to justify the translation of a word X by a word Y. But are we also to call it a justification if such a table is to be looked up only in the imagination? -- "Well, yes; then it is a subjective justification." -- But justification consists in appealing to something independent. -- "But surely I can appeal from one memory to another. For example, I don't know if I nave remembered the time of departure of a train right and to check it I call to mind how a page of the time -- table looked. Isn't it the same here?" -- No; for this process has got to produce a memory which is actually correct. If the mental image of the time -- table could not itself be tested for correctness, how could it confirm the correctness of the first memory? (As if someone were to buy several copies of the morning paper to assure himself that what it said was true.)

Looking up a table in the imagination is no more looking up a table than the image of the result of an imagined experiment is the result of an experiment.

I looked this up yesterday, as I wanted to double check I had As if someone were to buy several copies of the morning paper to assure himself that what it said was true right before I used it as a joke in a WhatsApp message.

On rereading the whole passage though, it strikes me as generally relevant to the 21st century, skewering as it does the models that underlie what we read about climate change projections and COVID infection forecasts etc.