From some of his quotes that I found on wikipedia and his SEP entries it seems that he considered essential to a sign it's relation to an interpreter and it's signified object. Can someone flesh out Bacon's views on the sign-interpreter relation?
I think this SEP article does a decent job at that:
Bonaventura (ca. 1217–1274), one of the most renowned theologians of the time, explicitly places emphasis on the sign's relation to the significate, claiming that
… a sign has a twofold comparison: both to that which it signifies, and to that to which it signifies; and the first is essential and the sign always has it in act, but the second it has in habit; and it is from the first that it is called a sign, not from the second. Whence a circle above a tavern is always a sign, even if no one looks at it.
In direct opposition to this commonly accepted manner of presentation, Bacon lay stress on the ‘pragmatic’ relation to the sign-interpreter, for the notion of sign is, as he claims, “essentially predicated with respect to someone to whom it signifies. … For if no one could conceive something through the sign, it would be void and vain, nay, it wouldn't be a sign.” (Roger Bacon, De signis, 1978, 81). Other than the essential relation of an actual sign to its interpreter, which must be in any a case what was called a ‘real relation’ (relatio realis), the relation to the significate can be a so-called a ‘relation of reason’ (relatio rationis), for, as Bacon adds: “It does not follow ‘a sign is in act, therefore the thing signified exists’, because nonentities can be signified by words just like entities” (Roger Bacon, De signis, 1978, 81). There are other important points in which Bacon deviates from the common opinion: He defines the sign as “that which upon being offered to the sense or intellect designates something to the intellect itself” (illud quod oblatum sensui vel intellectui aliquid designat ipsi intellectui), and emphasizes that, contrary to what the common description says, there are signs which are offered only to the intellect. (bolder mine)
Thus, he was ahead of his time in stating that
- a sign is something which gains its significance and status as a sign only insofar it is understood as a sign which is supposed to stand in a relation to its significate,
- signs can very well successfully signify something which does not exist,
- the designation happens purely intellectually, ie. the relation to the significate is not "objective" in the modern sense,
- there are signs that have no (independent) physical basis ("offered only to the intellect"), which I understand to mean that there can be contextually constituted meta-meanings (like sarcasm which only becomes obvious over several ambiguous statements taken together maybe?).