"truth-aptness", i.e. whether or not a statement in some sense can be either true or false, and if it can be, what is it true or false about, and how we decide whether it's true or false.
We can start with a loose interpretation of Popper's demarcation problem*. As best I can tell, Popper in The Logic of Scientific Discovery breaks with the Positivists. The Positivists'** project was to separate statements into "meaningful" and "meaningless": only statements that were (somehow, directly or indirectly) about perceptual events were meaningful; any statement that was not about perception was meaningless, in the same sense that "goo goo ga ga" is meaningless. An initially promising line of thought, Positivism ran into two severe problems. First, Positivism doesn't appear to be very useful: there are all sorts of things that we want to say, things that seem meaningful, but that we can't easily say using a Positivist definition of meaning. Perhaps more damningly, the Positivists couldn't seem to talk about Positivism itself using Positivist meaning. While the rest of the world might welcome a theory of meaning that renders philosophy impossible, philosophers found this exclusion intolerable. And since we really do need philosophy (even if we might be displeased with how professional philosophers might do philosophy), we ourselves have to reject Positivism.
*I'm not a philosophologer, so I'm not particularly interested in what Popper "really" meant; I am, rather, giving credit to Popper for at least inspiring my thinking on this subject.
**Same with Positivism
**Same with Positivism
What Popper does instead is talk about two different kinds of meaning: metaphysical and scientific*. Scientific statements are about the real world, and they can be true or false. Metaphysical statements are not about the real world; they are about how we look at the world. As such, a metaphysical statement is not "truth-apt": it is neither true nor false; it just "is what it is." Metaphysical statements are still meaningful: we do indeed have to look at the world, and it's meaningful to talk carefully, precisely and rigorously about how we look at the world, but there's no objectively "right" way to look at the world. (There are, of course, more or less interesting and useful ways of looking at the world.) Popper's definition of the demarcation is, of course, itself metaphysical: it's neither true nor false that statements "really are" divided into metaphysical and scientific.
*There can be, of course, more kinds of statements.
We need only a few statements describe the metaphysical basis of the scientific method. First, all statements about perception as statements about perception are authoritative, true by definition. Note that authoritative does not mean veridical: if I see a pencil bent when it's halfway in a bowl of water, it is true by definition that I see that it's bent; it is not, however, true by definition that the pencil really is bent. Second, a set of statements about the world that are themselves not specifically and directly statement of perceptions are about the world if and only if they are the "simplest" way of deducing the validity of some relevant authoritative statements of perception. We add a few statements about what constitutes relevance and "simplicity", and we have the complete metaphysical basis of the scientific method.
We can express scientific metaphysics in a few other ways. We can say that science is about discovering things about the world, and "the world" is, by definition, that which causes our perceptual experiences. We could also just dispense with "the world" and just say that science is about coming up with the simplest way to describe all of our experiences. As Popper noted, empirical science does not eliminate metaphysics, as the Positivists hoped to do. Instead, Popper's view renders metaphysics more tractable. We don't eliminate statements about the noumena or God just because they're "metaphysical"; we simply note that these kinds of metaphysical statements are incompatible with scientific metaphysics.
Because metaphysical statements are not truth-apt, because they are not the sort of statements we can say are either true or false, then we can't really "objectively" judge them*. We can't really say that scientific metaphysics are somehow "objectively" better than some religious or New Age woo-woo metaphysics. Using a particular metaphysical framework to understand the world becomes to a large extent a matter of taste and preference. But even though metaphysical statements are not truth-apt, they can be definite and particular. We can't say that scientific metaphysics is "objectively" better than religion, but we can "objectively" determine that they're different.
*Well, we can't judge them much. A metaphysical system might be vacuous (all statements are true) or internally contradictory, but
For example, a religious metaphysical system might add the metaphysical statement that by definition all statements in the Bible* are true. They might be literally true: if some statement that is true within scientific metaphysics contradicts the literal truth of a statement in the Bible, then within biblical-literal metaphysics the scientific statement is just false. A more "sophisticated" metaphysical system might hold that all statements in the Bible are true in some sense in addition to scientific truth, that the Bible gives us extra information that we are obliged to reconcile with scientific truth. But even biblical-literal metaphysics is not truth apt, neither true nor false: it's incoherent to say that even biblical literalism is false.
But we can say that biblical literalism or metaphoricalism is different from scientific metaphysics. Science simply does not define the Bible to be veridical: if the best scientific explanation for our perception contradicts a statement in the Bible, then the statement is just false. We are not obliged even to search for some alternative meaning that renders both science and the Bible true in some sense. We might do so, of course; when we read "Your breasts are like two fawns" (Song of Solomon 4:5) we apply a metaphorical meaning rather than determine the statement is simply false. We are not, however, obliged to preserve the truth of any statement in the same sense that the authority of perceptual statements "obliges" us to preserve their truth.
*Or the Koran, or the works of L. Ron Hubbard, or scripture du jour.
Which brings us back around to religion. We Gnu Atheists don't really care just that religion privileges a different kind of metaphysical system. We care, rather, that all too many religious people try to usurp scientific metaphysics, that they say that their God — and the moral prejudice they invoke their God to support — is scientifically provable. It's one thing to disagree with science; it's quite another to pretend that science agrees when it really disagrees. Similarly, in 1859 I would have disagreed with the laws permitting slavery and say that slavery ought to be illegal, but it would be dishonest for me to claim that slavery was actually illegal. We don't object to religion being different; we object to religious people trying to obscure or erase the difference.
The next post will cover paradigms.