M. A. I english P. C3 & C6 Modern Linguistics title pmd

8. 
Entailment
‘Entailment’ is a term for ‘formal logic’. The logical use of the term ‘entail’ 
derived from Moore’s (1919-20) paper ‘external and internal relations’. He preferred 
this word to ‘imply’. The term ‘entailment’ refers to inferences which represent a 
relationship between parts of a sentence‘s meaning such that the truth of the 
inferred proposition necessarily follows from the truth of the proposition expressed 
by the original sentence. 
Entailment is a crucial semantic relation. This relation can be defined in 
terms of valid rules of interference, or alternatively in terms of the assignment of 
truth or falsity to the propositions inferred Levinson (1983: 174) defined entailment 
as follows: 
A semantically entails B (written A II B) if every situation that makes A true 
makes B true (Or: in all worlds in which A is true. B is true) 
Entailment reflects a fixed truth relation between propositions expressed by a 
sentence which holds regardless of the empirical truth of the propositions. A 
proposition p is thus said to entail a proposition q if q is a valid inference from p 
irrespective of the empirical truth of p and q. It needs to be noted here that an 
entailment is a relation between propositions and not between sentences. 
An entailment relation is thus given to us by linguistic structure. We do not 
need to check any fact in the world to deduce the entailed proposition from the 
entailing proposition. In this case the first proposition ‘p’ necessarily implies, or 
entails the second proposition ‘q’ and the third proposition ‘r’.
Eg. ‘Booth assassinated Lincoln’, 
Then it is necessary in the case that ‘Booth Killed somebody’ and also that 
‘Lincoln died’. Such inferences are known as logical implications or logical 
consequences. In logical terminology therefore ‘entailment’ is said to be a relation 
that hold between ‘p’ and ‘q’- where ‘p’ and ‘q’ are variables standing for 
propositions – such that the truth of ‘q’ necessarily follows from the truth of ‘p’ and 

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falsity of ‘q’ necessarily guarantees the falsity of ‘p’. When this relation holds, then 
and only then a proposition ‘p’ entails proposition ‘q’.