Archive for the 'thought and world' Category

27
Jan
08

Hill’s Defense of (T&W-3)

Recall from this post the following statement:

(T&W-3) Propositions have structure that parallels the logical structure of the sentences.

Hill notes that this is a strong claim and one that is not universally accepted (T&W, 3), but presents a defense of it in a footnote (127) . I will reproduce the argument he presents, verbatim in most places, but restructured slightly:

Premise 1: (T&W-127-A) When one uses the predicate “believes that S” to attribute a belief to someone, the embedded sentence S indicates the proposition that serves as the object of the belief.

Premise 2: (T&W-127-B) The proposition that S indicates when it occurs in the predicate “believes that S” is the same as the proposition that S expresses when it is used in other contexts.

  (T&W-127-A) and (T&W-127-B) imply:

Lemma 1: (T&W-127-C)  If predicates “believes that S” and “believes that S*” can be used to attribute different beliefs, then the propositions, then the propositions that are expressed by the sentences S and S* must be numerically distinct.

Premise 3: (T&W-127-D) If there are any logical differences between S and S* (including even differences in microstructure), then the predicates “believes that S” and “believes that S*” can be used to attribute1 different beliefs.

 (T&W-127-C) and (T&W-127-D) imply:

Lemma 2: (T&W-127-E) Propositions are distinct when the sentences that express them are different in point of logical form.

Premise 4: (T&W-127-F) The best explanation of (T&W-127-E) is the hypothesis (T&W-127-G) .

Theorem: (T&W-127-G) Propositions have internal logical structures that reflect the logical structures of the sentences used to express them.

Corollary:    (T&W-3) Propositions have structure that parallels the logical structure of the sentences.

 1 The original uses “express” instead of “attribute” here, but I have edited this for the sake of consistency.

Advertisements
25
Jan
08

Propositional knowledge and beliefs

Our knowledge has a propositional structure; beliefs can be represented in the form of statements. I shall presuppose this concept of knowledge without further clarification…’ (TOCA, 8 )

Habermas is reluctant to elaborate on this presupposition. Thankfully, Christopher Hill, in Thought and World (T&W), isn’t:

When one has a belief, one is thereby related to a proposition. Thus, for example, if one believes that the universe is expanding, one stands in a certain psychological relation, the relation of believing, to the proposition that the universe is expanding. (T&W, 1)

Hill fleshes out what he means by “proposition” by making some assumptions about them:

…I will assume that that [propositions] have logical structure, and that concepts are their fundamental building blocks. ….
The assumption that propositions have logical structure should be stressed. It is intended in a very strong sense — specifically, as claiming that it is appropriate to view propositions as having constituent structures that parallel the logical structures of sentences. It is meant to entail, for example, that it is appropriate to regard the proposition Hannibal crossed the Alps and Caesar crossed the Rubicon as a complex structure consisting of two simpler propositions and a logical concept (the concept of conjunction). It is also meant to entail that it is appropriate to think of each of the simpler propositions as having an internal logical organization, an organization that can be expressed by saying that the proposition consists of two nominal concepts and a predicative concept that plays the role of a transitive verb. (T&W, 2-3)

The congruence between Habermas’ brief characterization of the propositional nature of beliefs (“beliefs can be represented in the form of statements”) and Hill’s characterization of the nature of propositions makes it tempting to conflate the two positions; so tempting, in fact, that I’m going to do it until it gets me into trouble. One of the purposes of this blog is to trace the extraction of a philosophical theory from the various sources that it draws from in a disciplined way. To this end, I will list some of the positions that have come up (at least under a cursory interpretation of the sources) so far below:

(T&W-1) When one has a belief, one is related in a certain way (the relation of believing) to a proposition.
(T&W-2) Concepts are the fundamental building blocks of propositions.
(T&W-3) Propositions have structure that parallels the logical structure of the sentences.

(TOCA-8-A) Beliefs can be represented in the form of statements.