Arguments for fruit flies being about as likely to be more morally significant than humans as less

Note the median moral weight for fruit flies assuming a loguniform distribution (the type I prefer) is 0.00192 << 1. So I do not think the moral weight of fruit flies relative to humans being smaller than 1 is as likely as it being larger than 1.

I think it's reasonable to say a fruit fly cannot remember things in the long term, and it cannot contemplate or ruminate, which is one of the worst aspects of negative experiences and pain. I think most people would prefer to have experiences of extreme pain and trauma erased from their lives.

Based on this analysis from Jason Schukraft, "mental time travel ["the capacity to remember past events and imagine future events"] seems to reduce the intensity of experiences in some circumstances and amplify the intensity of experiences in other circumstances. It is thus unclear whether animals that possess this ability have characteristically more or less intense valenced experiences overall" (see this section for details).

A fruit fly lives a tiny fraction of the duration of a human's life, so it would have to experience its own life much faster.

The moral weights presented here have units QALY/aQALY (QALY per "animal QALY"), and therefore they are not affected by differences in life expectancy between species. For example, a moral weight of 2 QALY/cQALY (QALY per "chicken QALY") means that 2 T years of fully healthy human life are as valuable as T years of fully healthy chicken life.

A human can be considered an ensemble or family of different personalities and conscious processes. Each one of these may have moral significance, increasing the relative moral significance of a human.

I tend to agree. From Jason's analysis (see here), "species that experience a greater variety and/or greater complexity of emotional states are, all else equal, capable of more intense positive and negative experiences".

The more complex something is, typically, it is more valued in generic terms.

From the "Key Highlights" of Jason's analysis:

• "Some aspects of cognitive sophistication appear to be positively correlated with intensity range; other aspects of cognitive sophistication appear to be negatively correlated with intensity range".
• "Affective complexity [diversity and depth of emotional sensations an animal can experience] generally appears to be positively correlated with intensity range".

So I tend to agree with your point, and think this is a good argument for not trusting mean moral weights which are much larger than 1. For the luguniform distributions, my maximum mean moral weight is 3, which is not much larger than 1.

Humans form a network of social connections and social connections. When a human is lost, their loss is understood and grieved by many other humans, thus greatly increasing the overall negative effect of harm to a human compared to a fruit fly.

Humans have very few children relative to fruit fly, so they are likely value higher on an individual level by their families and communities.

I agree, and think this should be considered when comparing interventions. That being said, these points do not influence the moral weight, which is the ratio between the value of T years of fully healthy animal life and T years of fully healthy animal life (i.e. the duration of the experiences is normalised).

A final thought is that we don't know with very high confidence that animals are conscious in the way that we care about morally, but we know this for sure with humans. For that reason, we would be safer to prefer to save humans first, in case we were wrong about animals having conscious experiences in the first place.

This is taken into account here by multiply the moral weight given moral patienthood by:

The probability of the beings of the species having moral patienthood, as defined by Luke Muehlhauser here, which was set to the values provided in this section of Open Philanthropy's 2017 Report on Consciousness and Moral Patienthood.

In terms of your summary:

In summary the most relevant factors for moral significance are likely the degree of social embeddedness, the experience of higher order emotions and complexity in general, the ability to grieve, long lives, and long memories, which strongly implies that humans are more morally significant than all or most other animals.

I think your conclusion may well be right, but there is lots of uncertainty, so I do not think there is a "strong implication". For example, I think the likelihood of the moral weight being larger than 1 is at least 10 %, so the mean moral weight should be larger than 0.1.

Thanks for commenting!

If the moral weight distribution is based on 2 theories A and B which produce distributions (lumps) MWA and MWB, and we think A and B are equally valid, the moral weight and expected moral weight would be:

• MW = 0.5 MWA + 0.5 MWB.
•  E(MW) = 0.5 E(MWA) + 0.5 E(MWB)

It is unclear whether this expected moral moral weight would be smaller/larger than the one of the continuous case. Luke only provides 2 quantiles, but MWA and MWB are defined by 4 parameters (assuming 2 for each). 

Eventually, to derive the 4 paramers, one could further assume that the variance of MWA equals that of MWB, and that the median of MW equals the arithmetic/geometric mean between Luke's lower and upper bound. However, I do not know whether these assumptions make sense.

Thanks for commenting!

In particular, what evidence helps you decide the presence of different aspects of consciousness in specific amounts?

What evidence helps you decide the moral weight of a person of one species relative to another?

In Luke's post, clock speed of consciousness, unity of consciousness, and unity-independent intensity of valenced aspects of consciousness are the factors based on which the quantiles for the moral weight were defined, I think.

Finally, What is EA speculation about more traditional models of morality that rely on a moral identity, judgements of right and wrong, and in particular, the symbolic importance of actions, even  when they have (potentially) minimal verifiable consequences for others (for example, catching a fly and releasing it outside)?

Personally, I put more than 90 % of weight on total hedonic utilitarianism (classical utilitarianism). However, in practice, the full consequences of my actions are really hard to measure, so I very often (always?) rely on heuristics to decide what to do (especially when there are "minimal verifiable [or measurable] consequences").

Note that cost-effectiveness analyses or other quantitative methods are still heuristics, not definitive answers, because they are always incomplete.