A perhaps-inconsequential question of psychological philosophy: what is the opposite of pleasure?
There is a very long and very august tradition of answering ‘pain’. The idea that the pair of opposite, ‘pleasure and pain’, is a key feature of how our mental lives work can be found in (at least translations of) philosophers from Aristotle to Bentham.
However, this opposition is also very clearly false. It only takes a little reflection to realise that the oppositeof pleasure is displeasure, and that this is not identical with pain.
For a start, the whole point of speaking of ‘pleasure’ in general is the thought that of any sensation that feels ‘good’ (and thus makes us want to pursue it), it can therefore be called ‘pleasurable’ to precisely that extent. But the same isn’t true of pain.
If we say of any sensation that feels ‘bad’ that it feels ‘painful’ to that extent, we deny the possibility of distinguishing a sensation which is a pain from one which is an itch, tickle, discomfort, nausea, tiredness, etc. But clearly an itch and a pain feel different.
Secondly, pains can vary in how displeasurable they are. They are like a taste: the taste ‘salty’ can be pleasant at one time (because you’re craving it) and unpleasant at another time (because you want something sweet), without necessarily changing how salty it is. Moreover, it can change its saltiness in a simple way (say, increasing) and change its pleasantness in a more complex way (at first it’s nicer, then past a certain limit it becomes unpleasant).
Similarly, pain is a sensation; a certain pain can be more unpleasant when, for instance, uncontrolled, and less unpleasant when inflicted on oneself deliberately – but it need not be less or more painful. And a twice-as-intensely pain need not be only twice as unpleasant – it might be much more. Sometimes pain can make an experience more pleasant – the pain that indicates resistance or heightens awareness, the pain of spicy foods, strenuous exercise, or self-harm to combat a far more unpleasant feeling empty numbness.
Of course we can use ‘pain’ is a general term for displeasure, and to some extent this is common and natural. But we can also use ‘sweet’ as a general term for pleasure. Sounds are ‘sweet’, faces are ‘sweet’, air is ‘sweet’ when we’ve been holding our breath, water is ‘sweet’ when we’re desperately thirsty, etc.
But a philosopher who tried to speak of all sensations as being either ‘unpleasant, sweet, or neutral’ would clearly be an idiot – philosophers should aim for clear and precise language, not language that makes ‘this is unpleasantly sweet’ self-contradictory, or which makes ‘this is pleasantly sweet’ and ‘this is pleasantly savoury’ mean the same thing.
So why would smart people use such a misleading way of speaking? My suspicion is that it helps to make a certain picture look more robust – the picture that can be roughly called ‘psychological hedonism’, the claim that people are always (or for some definite class of cases – Kant was a psychological hedonist in a certain sense) motivated by ‘seeking pleasure and avoiding displeasure’. This simplifying picture rests on the terms ‘pleasure’ and ‘displeasure’ having definite and measurable meanings – and a sensation like pain is much more definite and measurable than displeasure, which is a property of sensations.
Making the hedonistic picture seem more meaningful and solid is to the advantage both of those who want to promote it (e.g. utilitarians) and of those who want to set it up and then attack it (e.g. Plato, Kant). Why would people want to do these things? That’s a big question, but my suspicion is that the answer would not be a noble truth-seeking philosophical one, but rather an ideological one, though of a complex nature. ‘Hedonism’, ‘pleasure-seeking’, has a strong ideological link, for example, with the body, emotion and irrationality. This is relevant both to class distinctions and to gender distinctions. But I’ll leave that hanging.