What’s the most effective way to debunk moral relativism / subjectivism?

[mkm]

I suggested something similar when discussing with @mkm here, but I'm still not sure what to think about this. Maybe he'd be willing to explain his perspective?

In your example you wanted to have a infinite regression and obtain at the end something that has the same nature, as parts in the regression, i.e. languages. The problem is that by definition, formulas are finite, so ... => p_n => p_{n-1} => ... => p_0 is not a proper formula, but that's the outcome you wanted.
I don't know what do you want to achieve here, even ignoring for a moment the vagueness of the concept of transcendence.

[brimstoneSalad]

I agree that for objective morality it is needed a transcendental, objective and immutable reference of goodness. Otherwise you always crash against the "is-ought" problem.

Ought a knife be sharp?

It really depends. If you think that humanity should become extinct, for example,

I'm not talking about humanity here. Just the knife.
What is a knife? Given what it is (and yes this comes down to definition), should a knife be sharp?

We can talk about the teleology of instruments-- that is, meaningfully what they should ideally be based on their purpose.
A knife is meant to cut, so it *should* have the properties that make it good at serving that purpose, like being hard, durable, sharp, having an ergonomic handle even.

Is there really an is-ought problem when it comes to knife?
It IS a knife, therefore it ought X.
This doesn't seem to be a problem.

I think this comes due to the assumptions we make due to the definition of a knife, which includes that its function is to cut things. But I don't think you can draw an "ought" out of that.

Why not?

You just can say: Something is not a knife unless it is sharp.

No, you don't have to say that: you can just understand its function and then deduce from that and other empirical evidence the ideal properties that thing has to serve that function. It can be contextual too (as can moral oughts) it doesn't have to be absolute.

But should a knife be a knife or something else completely?

Are you asking about why the definition of words are as such?
Language has teleology too.

[Cirion Spellbinder]

Sorry, I think you thought I was trying to critique you. I remember agreeing with your conclusion, but I forgot why, and rereading didn't jog my memory. I do have a question though.

In your example you wanted to have a infinite regression and obtain at the end something that has the same nature, as parts in the regression, i.e. languages. The problem is that by definition, formulas are finite, so ... => p_n => p_{n-1} => ... => p_0 is not a proper formula, but that's the outcome you wanted.

Why are you allowed to go infinitely in the other direction then, like in a sequence: a_1+a_2+a_3+...+a_n+a_(n+1)+... ?

[mkm]

Why are you allowed to go infinitely in the other direction then, like in a sequence: a_1+a_2+a_3+...+a_n+a_(n+1)+... ?

When we consider an infinite sum like the one above, we look at the finite sum of the form a_1+a_2+...+a_N and check whether we can make the rest arbitrarily small, that's at least basic definition of convergent series. But you could for example take

...+a_{-n}+a_{-n+1}+...+a_0+...+a_{n-1}+a_n+...

and look at the finite sums of the form a_{-N}+a_{-N+1}+...+a_0+...+a_{N-1}+a_N and now check if you can make these two "tails" of the series arbitrarily small.

So, we are allowed to go in any direction we want, as long, as we know what we are talking about

[Cirion Spellbinder]

@brimstoneSalad
Can you explain minimal realism?

[brimstoneSalad]

@brimstoneSalad
Can you explain minimal realism?

Minimal realism holds that the semantic thesis is true (that when people talk about/use the word "morality" they're typically intending to make factual statements, rather than just say "I don't like this") and in addition to that, that some of those statements have truth value (the negation of that would be error theory).

There some disagreement about the boundaries and exact meaning. It's been called "creeping minimalism".

But what that seems to mean is very broad. Certain moral statements could just be false by being internally contradictory. Otherwise, they may be interpreted as true or false relative to some coherent definition of morality (which could be reason based, something like utilitarianism for example). It's not hard to be at least a minimalist.

Less wrong has a good article on what morality could mean:

https://www.lesswrong.com/posts/3zDX3f3 ... ductionism

[carnap]

Why would sentences making claims about the nature of the world not have a truth value?

You appear to be assuming one of the key issues, namely, that moral assertions are statements about "the nature of the world". After all, moral statements aren't empirical in nature so in what sense do they describe the world? Where do moral statements get their meaning? These are the sorts of questions you'd have to answer.

What if you rule out moral systems that aren't consistent with classical logic and use Occam's razor to determine the best consistent one?

I'm not sure what you mean here, how would you use Occam's razor to compare moral theories? Occam's razor applies to competing hypotheses of some given observation.

[carnap]

Whether you see concepts as fictions or not, there are truths to them. It's still true that Bilbo Baggins found an invisibility ring, even if just in a narrative. You could argue that's why the third metaphysical premise in moral realism is important and that minimal realism doesn't say much, but unless you're going to argue that and talk about what that premise would mean, none of this really contradicts minimal realism.

The issue has nothing to do with concepts, concepts in general don't have truth-value. Instead its a matter of what it means to say some particular sentence is true.

Saying "its still true" doesn't articulate what it means for a fictional sentence to be true. How one answers this is going to come down to various metaphysical issues and theories of truth.

But in any case, being a moral nihilist and making moral claims isn't mutually exclusive. Just as one can be a mathematician without being a mathematical realist.

[carnap]

Is there really an is-ought problem when it comes to knife?
It IS a knife, therefore it ought X.
This doesn't seem to be a problem.

This example is less problematic only because a knife was designed with a particular purpose and the tacit assumption is that an object ought to function with its intended purpose. But what is the purpose of a person? Without appeal to something outside of humanity, such as a god, you've just kicked the is-ought problem down the street a bit. You have no way to establish a normative purpose for a person.

[brimstoneSalad]

But in any case, being a moral nihilist and making moral claims isn't mutually exclusive. Just as one can be a mathematician without being a mathematical realist.

It isn't mutually exclusive if you're dishonest, no. Unless you contextualize your claims, like "A utilitarian would say..." but then that's not a moral claim.

It might be possible for a nihilist to make something that looks like a moral claim without being dishonest, it's not clear how though, since anything that appeared to be a moral claim would make strong implications that were dishonest misrepresentations of the beliefs of the person making them, and anything that didn't make those implications would have to avoid appearing as a moral claim.

A Mathematician isn't implicitly claiming mathematical realism by doing his or her job, it's just giving the employer an answer that satisfies his or her demand. A chef doesn't have to think whatever he or she is cooking tastes good or is healthy either; it's a product served at the demand of the customer.

This example is less problematic only because a knife was designed with a particular purpose and the tacit assumption is that an object ought to function with its intended purpose. But what is the purpose of a person?

It's not about the purpose of a person; it can also be about the purpose of language. Language has an intended purpose, and so does moral discourse; this purpose limits the definitions that would be consistent, and on that basis there are claims that are inconsistent and can be understood as false.

You have no way to establish a normative purpose for a person.

You don't need to, you can just look at the purpose of language and moral discourse.

However, that doesn't mean you certainly can't establish such a purpose (although that's beyond the scope of this discussion).