Theory and Reality (TR) 书中列举了四个 Hempel 作为逻辑经验主义者接受的观点：

(H1)

(H2)

(H3)

(H4)
D-N 模型允许对称的解释，或存在非相关问题的解释

As a fairly traditional empiricist, Hempel was attracted to the idea that the only possible role for those parts of language that seem to refer to unobservable entities is to help us pick out patterns in the observable realm. And if the parts of theories that appear to posit unobservable things are really any good, this “goodness” has to show up in advantages the theory has in its handling of observables. So there is no justification for seeing these parts of scientific language as describing real objects lying beyond experience. (TR, pp. 35-36)

(AR1)

(AR2)

(AR3)

[…] it is a mistake to express the scientific realist position in a way that depends on the accuracy of our current scientific theories. If we express scientific realism by asserting the real existence of the entities recognized by science now, then if our current theories turn out to be false, scientific realism will be false too. (ibid., p. 175)

Realists have argued that there is a continuum, rather than a sharp boundary, between the observable and the unobservable (Maxwell 1962). Some things can be observed with the naked eye, like trees. Other things, like the smallest subatomic particles, are unobservable and can only have their presence inferred from their effects on the behavior of observable things. But between the clear cases we have lots of unclear ones. Is it observation if you use a telescope? How about a light microscope? An X-ray machine? An MRI scan? An electron microscope? The realist thinks that the distinction between the observable and unobservable is vague, and not of the right kind to support general conclusions about what science aims to represent. (ibid., p. 185)

[…] to explain a phenomenon is not to explain it away. It is neither the aim not the effect of theoretical explanations to show that the familiar things and events of our everyday experience are not “really” there. The kinetic theory of gases plainly does not show that there are not such things as macroscopic bodies of different gases that change volumes under changing pressure, diffuse through porous walls at characteristic rates, etc., and that there “really” are only swarms of randomly buzzing molecules. (PNS, p. 78)

One possible reaction is to accept the conclusion. This was Hempel’s response. Observing a white shoe does confirm the hypothesis that all ravens are black, though presumably only by a tiny amount. (TR, p. 47)

A finding is relevant to H if either its occurrence or its nonoccurrence can be inferred from H. (PNS, p. 12)

Whether or not a black raven or a white shoe confirms “All ravens are black” might depend on the order in which you learn of the two properties of the object.
Suppose you hypothesize that all ravens are black, and someone comes up to you and says, “I have a raven behind my back; want to see what color it is?” You should say yes, because if the person pulls out a white raven, your theory is refuted. You need to find out what is behind his back. But suppose the person comes up and says, “I have a black object behind my back; want to see whether it’s a raven?” Then it does not matter to you what is behind his back. You think that all ravens are black, but you don’t have to think that all black things are ravens. In both cases, suppose the object behind his back is a black raven and he does show it to you. In the first situation, your observation of the raven seems relevant to your investigation of raven color, but in the other case it’s irrelevant.
So perhaps the “All ravens are black” hypothesis is only confirmed by a black raven when this observation had the potential to refute the hypothesis, only when the observation was part of a genuine test. (TR, p. 48)

(A)
$Ra \wedge \colorbox{yellow}{?}$
(B)
$\neg Ra \wedge \colorbox{yellow}{?}$
(C)
$\colorbox{yellow}{?} \wedge Ba$
(D)
$\colorbox{yellow}{?} \wedge \neg Ba$

Hypothetico-deductivism (HD)-confirmation

• $e$ 关于 $k$ HD-确证 $h$ 当且仅当 $h \wedge k \models e$ 并且 $k \nvDash e;$
• $e$ 关于 $k$ HD-否证 $h$ 当且仅当 $h \wedge k \models \neg e$, 并且 $k \nvDash \neg e;$
• 否则 $e$ 关于 $k$ 对假设 $h$ 就是 HD-中立的.

Probabilistic relevance confirmation

• $e$ 关于 $k$ 相关-确证 $h$ 当且仅当 $P( h|e \wedge k ) \gt P( h|k );$
• $e$ 关于 $k$ 相关-否证 $h$ 当且仅当 $P( h|e \wedge k ) \lt P( h|k );$
• $e$ 关于 $k$ 对 $h$ 是相关-中立的, 当且仅当 $P( h|e \wedge k ) = P( h|k ).$

$$P( H|\neg Ra \wedge \neg Ba ) - P(H) = P(H) \left[ \frac{P( \neg Ba|H )/P( \neg Ba )}{P( \neg Ra|\neg Ba )} - 1\right]$$