"What Animals are Like," David DeGrazia
- OVERVIEW
- "A wide range of animals, including most (or all) vertebrates (and probably
some invertebrates-octopus and squid) possess a rich variety of feelings"
- Examples
- Racoon cornered in a garage is fearful
- Fox who chews off her leg to get out of a trap is experiencing great
pain and suffering
- A dog whose owners have left it in a kennel for the first time and is
hypervigilant, jumpy and who urinates on the floor is anxious
- Empirical evidence strongly supports common sense view that animals have
states of awareness, even if their consciousness is less complex, reflective,
and language-laden than human consciousness typically is
- Sentience is capacity to have feelings
- Feelings include:
- Felt sensations (pain, nausea),
- Emotional states (fear, joy)
- To be sentient is to have states of awareness/consciousness/subjective
experience of at least of painful and pleasant sensations.
- PAIN
- Pain: an unpleasant or aversive sensory experience typically associated with
actual or potential tissue damage
- Nociception: "Detection of potentially harmful stimuli by neural end-organs"
- The machinery or plumbing of pain; 1st event usually lead to pain
- Detection of stimuli like cutting, pressure, pricking, heat cold
- Nociception need not involve pain
- In unusual cases, can be nociception w/o pain (or awareness)ExamplesSevered spinal cord allows a paraplegic to retain withdrawal reflect
but prevents pain
- Animal under general anaesthesia
- FOUR KINDS OF EVIDENCE FOR MENTAL STATES LIKE PAIN
- Human phenomenology (our experience of mental states lets us know what
they are like and allows us to categorize them and consider if animals have
them)
- Animals' behavior (do they engage in pain behavior?)
- Animals' physiology (do they have nervous systems similar to what allows
humans to feel pain?)
- Functional-evolutionary considerations (Would evolution have led to pain in
this animal? Would pain be adaptive for them? )
- Animal behaviors that are evidence for pain
- Avoiding/escaping noxious stimulus
- Majority of animals, including insects
- Some of this may be due to nociception w/o pain, nonconscious
response to stimuli
- Getting assistance (e.g., crying out) after noxious event
- Common among mammals, birds (only for social animals)
- Limiting use or injured body part to permit healing/rest (favoring a injured
limb)
- Vertebrates (and perhaps some invertebrates)
- Learning and adaptation to new circumstances strengthen claim that above
three behaviors indicate pain
- Vertebrates and at least some invertebrates (octopuses and squid)
- Physiological evidence for animal pain
- Great similarity in all vertebrate species of bio machinery necessary for pain
- Neurophysiology and neuroanatomy
- Measurable nerve impulses in specific pathways
- Metabolic and electrical activity in parts of brain
- Physiological changes in chemical systems in body in response to
pain stimuli
- Chemical responses to modulate pain-release of opiates
- Pain killers apparently control what is pain in all vertebrates (and
some invertebrates)
- We often use animals as models to study aversive mental states in humans
- Pain's function in evolution
- Pain provides an organism information about tissue damage
- Pain's unpleasantness provides motivation for adaptive, life-preserving
responses (moving limb away or favoring limb)
- Humans with impaired or no ability to feel pain risk not surviving
- While nociception w/o conscious pain might provide animals with
responses to avoid danger (how?), that humans experience pain and that
humans and vertebrates share very similar neural structures suggest that the
same mechanism is operating in both
- Natural selection has preserved the capacity for pain in the evolution
of at least all vertebrates
- CONCLUSIONS ABOUT PAIN
- Evidence overwhelming supports that many animals-including all
vertebrates-can feel pain
- Evidence today is too indeterminate to justify confidently drawing the line
between sentient and non-sentient animals in any specific place
- But virtually certain that some invertebrates (amoebas) are not
sentient
- DeGrazia (and many others) seems to point to a line between
vertebrates and invertebrates (except they place invertebrates like
octopus and squid with the vertebrates in ability to feel pain)
- Pain/sentience is uncertain in all but the most advanced invertebrates
(octopus/squid)
- Do insects feel pain?
- Show impressively complex behavior, including avoiding/escaping
harmful stimuli
- But often continue normal behavior after injury or loss of body parts
- E.g., don't take weight off injured limbsStrongly suggests lack of sentience
- Or a greater tolerance of pain?
- Extremely primitive nervous systems in comparison to vertebrates
- Short life spans and modest learning needs, suggest might get little
advantage from conscious states like pain
- A "startle reflex" might suffice to enable escape from danger
- DISTRESS, FEAR, ANXIETY, SUFFERING
- How they are different from pain
- Pain sensory (associated with specific body part)
- Distress, fear, anxiety and suffering are emotional (associated with entire
subject who experiences them)
- Suffering: Highly unpleasant emotional state associated with more than
minimal pain or distress (a high degree of pain or distress)
- DeGrazia assumes that most vertebrates can suffer
- Because all vertebrates can have pain and distress, unless one thinks
they are only capable of minimal amounts, they also can suffer
- DeGrazia rejects speculation that sentient animals are so primitive
that have only dim mental lives and thus cannot suffer.
- Distress (general category of emotions like fear, anxiety, frustration,
boredom)
- Unpleasant emotional response to perception of env. challenges and
harmful internal stimuli
- Due to approach of predators, belief one will fail, diarrhoea
- Difference fear/anxiety: Both are unpleasant emotional responses to
percieved danger, but fear is more focuses and anxiety is more general
- Example: First visit to vet's office cat has anxiety; second visit, she has fear
due to memory of painful shot
- Evidence for animal fear:
- All vertebrates have physiology that correlates with fear in humansAnd they behave as if afraid
- And this has great adaptive value
- Vertebrate animals show evidence of anxiety
- Similar behavior and physiological responses as humans
- pounding heart, sweating, increase breathing and pulsemotor tension, jumpiness
- hyperattention (e.g., visual scanning)
- Similar adaptive value and evolutionary function: inhibit action and
attend to env. getting ready of protective action
- Drugs that decrease or create anxiety in humans have the same
behavioral and chemical affects in some animals
- Randomly punishing thirsty rats reduced drinking (inhibit
normal behavior), giving them anti-anxiety drug restored
normal drinking rates.
- Most of studies mammals
- The physiological receptors in the body that anti-anxiety agents work
on were found in all vertebrates (amphibians, reptiles, birds and fish),
but not in invertebrates
- Differences human/animal anxiety: While evidence suggests anxiety in
vertebrates, not shown that human and animal anxiety qualitatively similar
beyond common unpleasantness and heightened arousal and attention
- Language laden complexity of human though produces anxious
experiences very diff from those of animals
- SKEPTICISM ABOUT ANIMAL MENTAL STATES
- Language or high states of rationality is necessary for awareness and
animals lack language
- Replies:
- Trained great apes and dolphins may well have language
- No reasons to think language/high rationality is necessary for having
feelings
- Human babies have feelings, but no language or high states of
rationality
- Some feelings (like fear of one's own mortality) may require
language to form such abstract thoughts, but not simple feelings like
pain and distress
- Animals lack self-awareness which is necessary for awareness
- Self awareness requires a notion of the self
- Why must all awareness involve awareness of oneself?
- Seeing a tree requires awareness, but visual awareness does not
require any conscious noting of who is doing the seeing
- DeGrazia thinks most vertebrates have temporal self-awareness
- Sense of themselves as existing over time
- Why? Because they experience fear, have expectations about the future, and
memories of the past (and these-often-involve self-awareness)
- Fear requires temporal self-awareness
- Fear is not poss unless one has some awareness of persisting into the
future
- One fears something that might happen to one
- Expectations about future self:
- Many animals have beliefs, desires and intentional action
- Example: If Rufus wants to go outside to bury the bone and intentionally
does so, Rufus has some awareness of self as persisting over time
- Desires usually concern future states of oneself and intentions carried
out over time
- Babies have sense of self because they desire their mother's breast?
- Evidence that vertebrates have memories (involving the self)
- Birds recall where hid food
- If any of animals memories or expectations include a representation
of the animal herself (remembering being hurt), that involves
temporal self-awareness