Grice and Quinton on "seem": the implicature

From p. 54 of "The problem of perception", repr. in Swartz,

"Of some uses of 'appear', 'seem', etc. it is clearly
untrue to say that they figure in descriptions of
experience."

---- (i) They appear to be away.

said when the twice-rung door-bell of a house
with drawn curtains remains unanswered, means
much the same as

---- (ii) They must be away.

or

---- (iii) They are probably away.

We are not describing, but drawing conclusions from,
what we observe. The word 'appears' serves to
indicate that these conclusions are drawn with
less than full confidence. There is nothing
basic about them."

---

Cfr.

Grice on:

"The pillar box seems red to me."