Julian Baggini, The Virtues of the Table (Granta, 2014), pp.53-54
(In discussing the ethics of eating meat, and the underlying moral question of killing animals)
… Here I think it is important to make a distinction between pain and suffering. Pain is simply that unpleasant sensation we have that has evolved as an alarm system for bodiy damage (although some alarms are false). There is no reason to doubt that any animal with a basic central nervous system feels pain, and even some crustaceans may feel some. To suffer, however, is not just to have a moment of pain, or even a series of pains. It is for pain to compound itself by accumulation, and that requires a certain amount of memory.
To illustrate this difference, imagine a person who retained no memory, conscious or otherwise, of any experience she had. Everything that happens is forgotten immediately. Imagine that this person is painfully pricked every ten seconds. These pricks, if unnecessary, are of course bad, but each individual prick is hardly terrible, and each successive prick is no worse than the one before it. It is as though on each occasion the person is being pricked for the first time. Now imagine if I were to prick you every ten seconds. It would not take long for you to be driven half mad. ‘Stop it,’ you’d say, because you were aware of this as an ongoing torment and would dread its indefinite continuation. The total amount of pain you felt would be the same as that of the amnesiac, but your suffering would be immeasurably greater. And this reflects a general truth: pain is bad, but suffering is much worse.
There is actually a good deal of experimental evidence to show that suffering and pan differ, as suffering is memory-dependent and we care more about it than mere pain. In the most striking experiment, patients who were given an endoscopy were asked to report their level of pain and discomfort while the procedure was being undertaken. Then, once it was all over, they were asked to rate how unpleasant the entire experience had been and how willing they would be to undergo it again. There were therefore two sets of results: a series of judgements made at the time and a final, retrospective assessment. It turned out that this final judgement depended more on when the most intense moment of pain was experienced that it did on the total amount of pain felt. As it happens, the most painful part comes right at the end of the procedure, and if it is stopped at this natural point, the patient judges the whole experience to have been very painful. But if you keep the endoscope in place, creating continued mild pain and allowing the discomfort to calm down a little, the patient’s final assessment is that overall the procedure was less painful than it otherwise would have been. This is deeply counterintuitive, because, of course, the second case, although judged to be less distressing, is exactly the same as the first, apart from the addition of some extra, mild discomfort at the end. There is more total pain but less total suffering. [He footnotes Daniel Kahneman, Thinking Fast and Slow (Allen Lane, 2011), pp.379-80).]
The reason for this is simple: pain is an unpleasant sensation, but it is experienced in present moments of awareness, which pass. What makes our self-consciousness more developed is not that we can experience moments — all animals can do that — but that we can create a narrative of our lives based on these experiences.