Imagine the worst possible suffering. The person suffering, when they are able to form a conscious thought, actively wants to die. The worst torture ever conceived. On a suffering scale, make that a 1,000 out of 1,000.
Now imagine the briefest, mildest unpleasant experience. Not even a stubbed toe -- maybe just a brief muscle spasm that you barely notice. Make that a 0.0001 on the suffering scale.
Is there any circumstance under which you would choose to save 10,000,001 individuals from the brief muscle spasm instead of saving the one person from torture?
And yet, that is what a strict utilitarian calculus would require -- prevent the most total suffering. The short takeaway is that I don't see that morality can be based on a simple summing across individuals (apologies to Parfit).
This is relevant in many situations, not the least of which is how we think about insects.
I agree with Dr. Greger that talking about insects with the general public is so strategically misguided that it causes actual harm. But I also think that it is philosophically mistaken as well.
I would be very comfortable betting my life that insects do not have subjective conscious experiences. Not to get into the weeds, but I believe people too easily conflate behavior with consciousness. The ability to sense things -- "sentience" in its broadest meaning -- exists all the way down to single-cell organisms (Carl Sagan once told me this is why "sentience" per se couldn't be the basis of morality). To me, all the evidence indicates that the ability to have conscious, subjective experiences -- to be able to actually suffer -- derives from and requires significant neural complexity (sorry Chalmers). And once the appropriate level of complexity is reached, further complexity can lead to a greater capacity for consciousness. That is, the ability to feel feelings is not binary, but analog. (For much much more, please see this. I don't fully agree, but it is the most honest and thorough treatment of consciousness I've ever come across.)
So even if insects can have any subjective experience, their most intense sensation would be the palest hint of a feeling -- a tiny fraction of the worst suffering we can experience.
Just as no number of people having a brief muscle spasm could rise to the level of concern of one person being tortured, no number of insects being made to experience their "worst" suffering rises to the level of concern of a single person suffering anywhere near their worst.
Note: I'm not saying I have a coherent replacement for utilitarianism. I realize the contradictions in this view. Just as I would save one person from being tortured instead of sparing a trillion people from experiencing a muscle spasm, I would be inclined to save multiple people from suffering at level 999 vs one person at level 1,000. However, I can imagine myself being convinced that the latter is wrong; i.e., that I should always care about relieving the worst-off suffering. On the other hand, I currently can't imagine being convinced to care about insects, especially in a world with so many individuals clearly suffering so intensely.
Finally, I realize the above seems to contradict my concern for chickens. The reason isn't a love for chickens, but rather, marginal impact.
I could be convinced that I should do something with my life that would help individuals who are suffering worse than chickens -- individuals who wouldn't be helped if not for my specific efforts. But I've not yet come across that argument. Loads of people care about mammals, and loads more care about humans. But few people care about chickens, even though the average chicken is basically tortured. Even assuming chickens have a lower capacity to suffer than a cow, I'd rather be reincarnated as an average steer than your average chicken. (I'd easily choose being reincarnated as a bug over either of those options!) Yet most of our dietary advocacy leads to more chickens suffering.
I could be wrong -- I've changed my mind before.