Adverbial clauses occur in complex sentences, in which two (or more) propositions are combined to produce a single complex proposition. However, not all adverbial clauses have the same semantic properties. The examples in (1–2) illustrate some of the differences between time clauses and reason clauses:
(1) a. Prince Harry wore his medals when he visited the Pope.
b. Prince Harry didn’t wear his medals when he visited the Pope.
c. Did Prince Harry wear his medals when he visited the Pope?
(2) a. Arthur married Susan because she is rich.
b. Arthur didn’t marry Susan because she is rich.
c. Did Arthur marry Susan because she is rich?
So q because p does not presuppose that p is true; but it entails that both p and q are true. This entailment is demonstrated in (3).
(3) a. George VI became King of England because Edward VIII abdicated; #but George did not become king.
b. George VI became King of England because Edward VIII abdicated; #but Edward did not abdicate.
A second difference between time clauses and reason clauses involves the effect of negation. The negative statement in (2b) is ambiguous. It can either mean ‘Arthur didn’t marry Susan, and his reason for not marrying her was because she is rich;’ or ‘Arthur did marry Susan, but his reason for marrying her was not because she is rich.’ No such ambiguity arises in sentence (1b).
The time clause in (1a) functions as a modifier; it makes the proposition expressed in the main clause more specific or precise, by restricting its time reference. Because clauses seem to have a different kind of semantic function. Johnston (1994) argues that because is best analyzed as an operator CAUSE, which combines two propositions into a single proposition by asserting a causal relationship between the two.2 We might define this operator as shown in (4):
(4) CAUSE(p,q) is true iff p is true, q is true, and p being true causes q to be true.
For example, if p and q are descriptions of events in the past, CAUSE(p,q) would mean that p happening caused q to happen. A truth table for CAUSE would look very much like the truth table for and; but there is a crucial additional element of meaning that would not show up in the truth table, namely the causal relationship between the two propositions.3
This analysis provides an immediate explanation for the ambiguity of sentence (2b) in terms of the scope of negation:
(5) Arthur didn’t marry Susan because she is rich.
a. ¬CAUSE(RICH(s), MARRY(a,s))
b. CAUSE(RICH(s), ¬MARRY(a,s))
If this approach is on the right track, we would expect to find other kinds of scope ambiguities involving because clauses as well. This prediction turns out to be correct: in sentences of the form p because q, if the first clause contains a scope-bearing expression such as a quantifier, modal, or propositional attitude verb, that expression may be interpreted as taking scope either over the entire sentence or just over its immediate clause. Some examples are provided in (6–7).
(6) Few people admired Churchill because he joined the Amalgamated Union of Building Trade Workers.
a. CAUSE(JOIN(c,aubtw), [few x: person(x)] ADMIRE(x,c))
b. [few x: person(x)] CAUSE(JOIN(c,aubtw), ADMIRE(x,c))
(7) I believed that you love me because I am gullible.
a. BELIEVE(s, CAUSE(GULLIBLE(s), LOVE(h,s))
b. CAUSE(GULLIBLE(s), BELIEVE(s, LOVE(h,s)))
[s = speaker; h = hearer]
One reading for sentence (6), which is clearly false in our world, is that only a few people admired Churchill, and the reason for this was that he joined the AUBTW. The other reading for sentence (6), very likely true in our world, is that only a few people’s admiration of Churchill was motivated by his joining of the AUBTW; but many others may have admired him for other reasons. (The reader should work out the two readings for sentence (7).)
2 This operator is probably different from the causal operator involved in morphological causatives, which is often thought of as a relation between an individual and an event/situation.
3 The definition of causality is a long-standing problem in philosophy, which we will not address here. One way to think about it makes use of a counter-factual (see Chapter 19): CAUSE(p,q) means that if p had not happened, q would not have happened either.
