Assuming you argue for X, but you don’t believe X, it would seem something is wrong, at least from the individual rationality perspective.
Belief is a matter of degree. If someone else thinks it’s 10% likely to be raining, and you believe it’s 40% likely to be raining, then we could summarize that as “both of you think it’s not raining”. And if you share some of your evidence and reasoning for thinking the probability is more like 40% than 10%, then we could maybe say that this isn’t really arguing for the proposition “it’s raining”, but rather the proposition “rain is likelier than you think” or “rain is 40% likely” or whatever.
But in both cases there’s something a bit odd about phrasing things this way, something that cuts a bit skew to reality. In reality there’s nothing special about the 50% point, and belief isn’t a binary. So I think part of the objection here is: maybe what you’re saying about belief and argument is technically true, but it’s weird to think and speak that way because in fact the cognitive act of assigning 40% probability to something is very similar to the act of assigning 60% probability to something, and the act of citing evidence for rain when you have the former belief is often just completely identical to the act of citing evidence for rain when you have the latter belief.
The issue for discourse is that beliefs do come in degrees, but when expressing them they lose this feature. Declarative statements are mostly discrete. (Saying “It’s raining outside” doesn’t communicate how strongly you believe it, except to more than 50% -- but again, the fan of championing will deny even that in certain discourse contexts.)
Talking explicitly about probabilities is a workaround, a hack where we still make binary statements, just about probabilities. But talking about probabilities is kind of unnatural, and people (even rationalists) rarely do it. Notice how both of us made a lot of declarative statements without indicating our degrees of belief in them. The best we can do, without using explicit probabilities, is using qualifiers like “I believe that”, “It might be that”, “It seems that”, “Probably”, “Possibly”, “Definitely”, “I’m pretty sure that” etc.
See
https://raw.githubusercontent.com/zonination/perceptions/master/joy1.png
Belief is a matter of degree. If someone else thinks it’s 10% likely to be raining, and you believe it’s 40% likely to be raining, then we could summarize that as “both of you think it’s not raining”. And if you share some of your evidence and reasoning for thinking the probability is more like 40% than 10%, then we could maybe say that this isn’t really arguing for the proposition “it’s raining”, but rather the proposition “rain is likelier than you think” or “rain is 40% likely” or whatever.
But in both cases there’s something a bit odd about phrasing things this way, something that cuts a bit skew to reality. In reality there’s nothing special about the 50% point, and belief isn’t a binary. So I think part of the objection here is: maybe what you’re saying about belief and argument is technically true, but it’s weird to think and speak that way because in fact the cognitive act of assigning 40% probability to something is very similar to the act of assigning 60% probability to something, and the act of citing evidence for rain when you have the former belief is often just completely identical to the act of citing evidence for rain when you have the latter belief.
The issue for discourse is that beliefs do come in degrees, but when expressing them they lose this feature. Declarative statements are mostly discrete. (Saying “It’s raining outside” doesn’t communicate how strongly you believe it, except to more than 50% -- but again, the fan of championing will deny even that in certain discourse contexts.)
Talking explicitly about probabilities is a workaround, a hack where we still make binary statements, just about probabilities. But talking about probabilities is kind of unnatural, and people (even rationalists) rarely do it. Notice how both of us made a lot of declarative statements without indicating our degrees of belief in them. The best we can do, without using explicit probabilities, is using qualifiers like “I believe that”, “It might be that”, “It seems that”, “Probably”, “Possibly”, “Definitely”, “I’m pretty sure that” etc. See https://raw.githubusercontent.com/zonination/perceptions/master/joy1.png