Types of Propositions

by Luke Muehlhauser on May 9, 2009 in General Atheism,Reviews

I’m blogging my way through Sense and Goodness Without God, Richard Carrier’s handy worldview-in-a-box for atheists. (See the post index for all sections.) Last time, I discussed section II.2.1 The Meaning of Words. Now we’re ready to talk about the useful arrangement of words into sentences – and more specifically, propositions: sentences that can be true or false based on whether or not they make true predictions.

Note that many sentences are not propositions, for example: “Can I go out and play?” or “Do your homework first.” or “Fuck you, mom!” These sentences are not true or false; they are used to express other types of meaning.

Types of propositions

There are many types of propositions. The first is the definition. For example: “Cats are felines.” This is true simply because we’ve defined it to be true, like “2 + 2 = 4.”

We can also make stipulative definitions, as in: “For the purposes of this debate, ‘God’ is defined as the all-knowing, all-powerful, all-loving personal being who created the universe.” This is true because we defined it to be true for this particular situation. (And then, the debaters would commence arguing about whether God, so defined, actually exists.)

Another type of proposition is the descriptor, for example: “Cats are mammals.” This means that cats have the qualities that are associated with mammals: a skeleton, mammary glands, hair, a nervous system, DNA, etc.

Perhaps surprisingly, Carrier says that propositions can also express opinions, as long as we remember that an opinion says something that is true or false about an individual’s feelings. For example: “Cats are cute” is true if we understand it to mean something like, “Cats are charmingly attractive to the speaker.” This kind of statement can also be false, for example if I tell a girl I think her swollen belly is cute even though it is not charmingly attractive to me.

There might also be moral propositions, but we’ll get to those when I review Richard’s sections on morality.


The final type of proposition is the factual claim, which is a “hypothesis” that predicts something about human experience.

That’s how Carrier puts it on page 40, anyway. But remember, Carrier said earlier that all propositions make predictions about human experience. As Carrier explains on page 41:

All the other types of proposition can actually be described as types of hypothesis, as different kinds of claims to fact. For they all make predictions. References (lexical definitions) predict that if any copy of the implied lexicon is consulted… the stated meaning will be experienced. So “cats are felines” is true if the code word ‘cat’ is actually found to be equivalent to the code word ‘feline’ in some actual lexicon…

Descriptions… predict that if the thing being described is experienced, the features stated in the description will also be experienced. [If "Roses are red," then wherever roses are experienced, redness should also be experienced. Of course this is false, as some roses are not red. Also, I'd like to clarify for Carrier that "Roses are red" may have to be taken to mean something like "Rose petals are red when they are biologically normal and white light is shining on them."]

In the case of opinions, they claim that someone actually has the stated opinion.

Through some unnecessary mental gymnastics, Carrier also asserts that wishes and commands are propositions, but I don’t think it’s useful to think of them as such.

Anyway: to Carrier, all propositions are factual claims, which have meaning and make predictions.


So then, if we have properly understood the meaning of a proposition, and we know what predictions it would entail, how do we tell if the proposition is true or false? Carrier says, “a statement is true if the experiences it predicts will actually be experienced under the implied conditions… given the absence of errors, interfering circumstances, and so on, and accounting for modifiers where appropriate (like ‘sometimes’ or ‘often’ or ‘probably’).”

Next, I’ll discuss II.2.2.8 Naturally Warranted Belief, in which Carrier defends his views from two attacks of Christian philosopher Alvin Plantinga.

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{ 4 comments… read them below or add one }

Matt McCormick May 9, 2009 at 12:12 pm

Thanks for linking and referring to my site, L.  The traffic is appreciated.  

From the post, and I haven’t read Carrier’s book, it sounds like he’s confused about the difference between a proposition being true and someone having adequate justification to believe that it is true.  They are different.  The truth, philosophers typically maintain, is the state of affairs in the world that is the case.  But you may or may not have a belief that matches or maps onto that.  And you may or may not be able to make successful predictions or have justification about what is true.  You can also make successful predictions on the basis of some claim you believe, but it is false.  

Again, thanks for the support on my blog.  



lukeprog May 9, 2009 at 1:29 pm


This is actually Carrier’s account of what propositions actually are. As you can see, it’s roughly a positivist account.


Ben May 11, 2009 at 10:01 pm

“Through some unnecessary mental gymnastics, Carrier also asserts that wishes and commands are propositions, but I don’t think it’s useful to think of them as such.”

I have to disagree with you, because if we go with Carrier, everything is grounded in reality in some way, whereas if we go with where it appears you go, things start getting free floatie and nonsensical.  I’m assuming you aren’t a Platonist and that you are a physicalist, right?  Well then think of what it would take to be able to program an A. I. to be able to use all sorts of propositions including commands and wishes and you will likely see why Carrier is on the right track.  It all has to work and be connected and this doesn’t seem to have a lot to do with positivism.  Perhaps in a subjective way Carrier is “more positivist” than you are, but that doesn’t make him a positivist any more than Obama’s government strategies that are “more socialist” than Republican strategies make Obama a socialist.  I’ll drill nuance into you yet!  haha :p

I do enjoy the retour of Carrier’s book. 



lukeprog May 12, 2009 at 7:04 am


Why does all speech need to be a proposition to avoid being “floatie and nonsensical”? Do you think a physicalist has no account for grunts, whines, commands, and wishes unless he asserts that they are misinterpreted propositions?


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