Do Animals Actually Feel Pain?

If they don’t feel pain, it would be a pretty solid reason to eat meat again. If animals don’t feel pain, there is no suffering, and if there’s no suffering, there is no cruelty.

Firstly, what is pain?

Similar to the “plants feel pain” argument, let’s begin with the definition of pain.

The International Association for the Study of Pain (IASP) defines pain as:

An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.

The keyword here for our understanding is “emotional”. It is a subjective, conscious experience, which means this is a feeling that is only happening in one’s own mind. For a living thing to experience pain, it needs a nervous system capable of conscious experience, not just one that reacts.

The IASP also adds this note to its definition:

Verbal description is only one of several behaviors to express pain; inability to communicate does not negate the possibility that a human or a nonhuman animal experiences pain.

Let’s see what the science says about animal pain and consciousness:

Do animals have the capacity to biologically feel pain?

It’s a biological fact that mammals, birds, and fish have a brain, a central nervous system, and nociceptors (pain receptors).

This paper, Evolution of nociception and pain: evidence from fish models, sums it up:

All animals are considered capable of nociception, which is the detection of potentially injurious stimuli, and is usually accompanied by a nocifensive withdrawal reflex away from that stimulus.

I don’t think it is controversial to say that animals have the biological hardware to detect an injury. Let’s move on to the more interesting question:

Can they consciously feel it?

They may have the biological “hardware,” but sceptics often argue that animals don’t have the “software” to consciously experience it.

This is the difference between nociception and pain. Nociception is just pulling your hand away from a hot pan before you’ve even registered it, with no conscious experience involved. The real question is whether animals also feel it.

One study involving chickens with clinical lameness (pain due to leg problems) let them choose between two food sources: one with a painkiller and one without. The lame birds tended to consume more analgesic than sound birds, indicating that they were actively seeking pain relief.

Fish show it too. I look into this in more detail here

There are also studies showing that household pets recovering from surgery demonstrate behaviours reflective of pain, which are alleviated when they are treated with analgesics.

They can’t tell us in words, but their behavioural choices show evidence of the software.

The Scientific Consensus

In 2012, a group of cognitive neuroscientists, neuropharmacologists, and neuroanatomists came together to evaluate this exact question.

They signed The Cambridge Declaration on Consciousness, concluding:

“the weight of evidence indicates that humans are not unique in possessing the neurological substrates that generate consciousness. Non-human animals, including all mammals and birds, and many other creatures, including octopuses, also possess these neurological substrates.”

In 2024, a larger group of scientists and philosophers went further with The New York Declaration on Animal Consciousness, stating there is “strong scientific support” for conscious experience in mammals and birds, and “at least a realistic possibility” of it in all vertebrates (including fish) and many invertebrates.

It’s generally accepted in the scientific community that animals feel pain in a way that matters. We share the hardware, and their behaviour shows the software.

Animals have the same biological machinery for feeling pain that we do.