Assess the philosophical significance of the claim that to understand a proposition is to know its truth conditions.
In discussing this claim from the beginning we might say that the claim when initially stated has two possible interpretations. One might be to argue that a proposition viewed as a sentence in a carefully constructed symbolic logic has truth conditions. All propositions viewed in this way are either true or false, or they are tautologies or contradictions. Logical propositions in a logical language function this way. That makes them interesting to logicians, but it is unclear that people using language in ‘the world’, (ie a natural language as opposed to a logical or symbolic language) make propositions in this sense. The second interpretation is that what people do with statements ‘in the world’ is in fact make propositions that can be assessed as true or false. If we want to talk about natural language and its meaning we have to look at the second interpretation. If we look at the second interpretation we have to actually account for what language users really do, or mean to do, with statements, and not just what in a ‘perfect’ logical world they might or should do. Otherwise we might be arguing that we understand a language user’s proposition when they themselves did not understand it. This might be one way of looking at natural languages, but it raises a question of what understanding really is.
The move from the first interpretation to the second has its origins in the history of analytical philosophy. In analytical philosophy the idea that to understand a proposition is to know its truth conditions has its origins in the application of a predicate calculus (ie a logical language) to the logical analysis of natural language sentences and the deconstruction of natural language sentences to logical syntax. The original idea was that natural language sentences hide a clear logical syntax that can be used to accurately portray and describe their truth function. The development of the theory was to argue that all natural language statements are also propositions with truth conditions.
But in making a move from a logical language to a natural language we cannot escape the implications indicated above ie accounting for what natural language speakers actually intend to do with their statements. In my opinion the claim that for a natural language to understand a proposition is to know its truth conditions is a claim about knowing what a statement means, not just ‘in itself’ but to both the users and the receiver. The claim seeks to clarify what language users are doing with language when they make statements. That is what they mean when they make a statement. And also importantly what the person they communicate to thinks they mean.
By continuing our analysis of the claim as applied to natural language statements or propositions we can draw out several important implications. Firstly, the claim limits its linguistic target. Natural languages are not entirely comprised of carefully constructed propositions. This particular claim does not appear to be able to deal with other aspects of language like metaphors, riddles and lies. The front page of a newspaper after a speech by the prime minister the previous day states ‘The lion roared!’. What are the truth conditions of this proposition? Do you really ‘understand’ the statement if you break it down to a logical syntax? This is the implication of arguments put forward by Wittgenstein in his later philosophy that there are many language games. Statements or propositions that are trying to get at truth are just one way of using language. Thus as a claim about language, it is not an all encompassing theory that will help us understand ‘meaning’ in every context.
Secondly, the claim has implications for how we view the activities of language users. On one view we might try to claim that people make statements that are purely for interest sake, with a complete lack of commitment to how the state of affairs in the world actually are. Jack says ‘Grass may be green, or it may not be green.’ Jill says ‘Isn’t that interesting?’ You might then say that understanding a proposition is knowing what would be the case if the proposition was true. We could then add that the claim that ‘to understand a proposition is to understand its truth conditions’ does not necessarily entail that the speaker or receiver of the statement need to actually know ‘the truth’, if it exists or can indeed be known. But clearly this is not what language users intend to do most of the time with language. If I was to comment to a child learning a language that ‘we are teaching you how to say what would be the case if this is true’ they would think I was mad. In my opinion to view language in this way is to regress to the first interpretation of the claim. It is to regress from the world of natural language back to the world of logical languages. In fact the implication of this thought might be to say that a logical language is one type of language game. Not a common one.
So what do language users actually intend to do with propositions. Maybe they intend to say what they believe is the truth. Maybe they don’t intend to speak the truth (ie they lie or deceive or play a game). Maybe they don’t know (or care) what the truth is but they say something anyway (people like talking).
Imagine the (I believe not uncommon) scenario when a couple leave a dinner party. One says ‘What did you think about what Joe said about John?’. The other replies ‘Oh, he didn’t really mean that’. How are we to interpret the concept ‘understanding’ in this context.
But what if we do view the activities of language users as ‘aiming for truth’ when they use sentences or propositions? It would be just to argue that a language user aims for what they think is the truth. This is probably what most language users are doing with propositions most of the time. If we reject the idea that the user in this instance is intending to state what would be the case if the proposition is true, then in this context understanding the ‘truth conditions’ would mean knowing ‘the truth’, being able to label the proposition as ‘true’ or ‘false’. We then arrive at the need for a way of knowing whether what they said is correct or not. Whether their statement can be verified. An adequate theory of epistemology.
We don’t have such a theory. Science is one strategy to verify statements or propositions. It is a powerful but limited strategy. It ‘works’ within the context of specific rules and limitations. You could argue that science is a strategy that fits into one language game (albeit a particularly important one). But it does not account for many propositions or meaning related statements. Verification or truth is limited by our perceptual abilities, by paradoxes like the paradox of the heap, by new information.
In my opinion (following Wittgenstein’s latter philosophy) the central problem with the claim ‘that to understand a proposition is to understand its truth conditions’ is that it separates the proposition from the person who proposes the proposition, and in doing so removes it from the ‘forms of life’ and the language games that give propositions meaning. It implies that the ‘understanding’ of a proposition is an abstract concept that has no need to account for what is intended by the language user or the context in which they use it.
© Tom Georgeson 2018