Another old, but still relevant, quote…
And thus, a true Theory is a Fact; a Fact is a familiar Theory. That which is a Fact under one aspect, is a Theory under another. The most recondite Theories when firmly established are Facts: the simplest Facts involve something of the nature of Theory. –William Whewell Philosophy of the Inductive Sciences (2nd ed, 1847)
this is all well and good so long as the theory is true. when the theory is not true, then it is not a fact. there are theories that are false. for a theory to be a fact it must not only be firmly established, but also true. there have been firmly established theories that now appear to have been false.
i think the best point Whewell makes is the last: that the simplest facts involve something of the nature of theory…
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