It drives me crazy (not really, of course) when atheists (and lately even some scientists) assert that evolution is a “fact”.
Now, the word “fact” can have various (conflicting) meanings. For example there is a sense in which calling something a “scientific fact” simply means “most scientists agree” it’s true. In that sense I’m sure everyone would admit that evolution is a fact. But it’s a weak use of the word “fact”—and not at all the sort of thing most of us mean when we call something a fact.
Of course, if we examine “facts” closely enough we discover that they become less and less “factual” the more we look—but I won’t go into that here. I don’t want sound like what my younger daughter used to call “a crazy philosopher guy” who “gives people headaches” when she was a child. I’ll avoid casting too critical an eye on factuality and stick with the ordinary meaning of the word.
Facts are the evidence upon which inferences and hypotheses and theories are built. So in ordinary usage if you see a red apple on the table, that there is a red apple on the table is a fact. If someone then lays a table cloth over top the apple, so that now you only see an apple-sized lump under the table cloth where previously you saw the apple, it is now an inference rather than a fact that there is an apple on the table.
Is it a sound inference? Probably so—unless you are attending a magic show and the person who placed the cloth over the apple is a magician. Magicians, after all, make their living by tricking audiences into false inferences, or confusing inferences with facts.
Consider a simple magic trick. The magician sets a glass of water on the table, and then asks a member of the audience for a quarter. Magician holds the quarter up for all to see, then takes a handkerchief and drapes it over the quarter. With two fingers he holds the quarter up, hidden by the handkerchief, so that you can make out the circular shape of the quarter underneath. The magician even passes it to an audience member to hold (without peaking underneath the handkerchief, of course.) Finally the magician asks the audience member to hold the handkerchief and quarter over the glass of water and let go, so that the quarter should fall into the water (and the handkerchief drape over the glass). He then asks the volunteer to pull the handkerchief away and reveal the glass of water.
The quarter is gone! Disappeared. The magician even pours the water slowly out of the glass and dramatically holds the glass upside down—no quarter!
Where is the false inference? In this case, when the magician covered the quarter with the handkerchief, he swapped the quarter with a piece of glass the size and shape of a quarter. The glass may not weigh exactly the same as a quarter, but draped under the weight of the handkerchief, who can tell? When the quarter-sized glass is dropped into the water it is for all practical purposes invisible, especially to an audience expecting to see a real quarter. The surface tension of water makes the glass quarter cling to the bottom of the drinking glass even when it is held upside down.
All magic tricks rely on inducing the audience into mistaking inferences for facts. If you want to avoid being tricked, one thing you must do is become acutely aware whether you are inferring something or directly observing it. The apple on the table is a factual observation, but the apple-sized lump under the tablecloth is only an inference.
So, is the origin of species by evolution (whether by natural selection or otherwise) fact or inference? Do we see evolution happening the way one sees an apple on the table, or is species change not observed directly but rather based on a set of inferences? The answer, I think, is obvious.
All scientific theories are built on inferences from facts, and are therefore never factual themselves. They are always—oh, what is the word?—oh yes, now I remember—they are always theoretical rather than factual.
