Lauren asked:

I have a question in my textbook that I was wondering if you could help. The question is:

How would Heraclitus have responded to the following statement? ‘Heraclitus’ theory is wrong because the objects we see around us continue to endure throughout time; although a person, an animal or plant may change its superficial qualities, it still remains essentially the same person, animal or plant throughout these changes. In fact, we recognize change only by contrasting it to the underlying permanence of things. So permanence, not change, is the essential to reality.’

Answer by Helier Robinson

There is a fundamental principle that any qualitative difference entails a quantitative difference. It is easily proved, as follows: whatever A and B may be, if there is a qualitative difference between them then there is some quality, Q, such that A is Q and B is not-Q (or vice versa); if A and B are one, then one thing is at once Q and not-Q, which is impossible, so A and B are two. So Heraclitus would have responded that if something changes then the earlier thing is qualitatively different from the later thing and so the earlier and later things have to be two – in which case it is quite wrong to suppose that there is one, permanent, thing changing through time. (A change is a qualitative difference in parallel with a duration.) It does not matter how superficial the change is: the principle that qualitative difference entails quantitative difference applies to any qualitative change whatever.

There is another point that Heraclitus could have made: how do you know that empirical objects continue to endure through time? This is only a belief. To be sure, it is a belief of common sense, and so held by most of us, but there is an opposing belief that empirical objects are not real objects, they are only images of real objects, and as such they exist only for as long as they are perceived. Esse est percipi as Bishop Berkeley said: to be is to be perceived; and empirical objects are perceived objects. This view arises because the only satisfactory explanation of illusions is that since they are unreal they have to be misrepresentations (or false images) of reality, not reality itself.

Heraclitus could also have said that we do not in fact recognise change by contrasting it to the underlying permanence of things, we perceive it directly. Look at clouds on a windy day: do you see them changing, or do you contrast them to their underlying (whatever that is) permanence?

It is worth noting in this context that Parmenides’ rejection of Heraclitus is based on the same principle that qualitative difference entails quantitative difference. For him, all change is illusion and so nothing really changes so only permanence is real.

And finally, this principle has some awkward consequences for philosophy. For example, your empirical world is qualitatively different from mine, so yours and mine must be two, they cannot be one. And by extending this argument, there must be as many empirical worlds as there are perceivers. And because each of these empirical worlds contains illusions, they are all qualitatively different from the real world, so none of them is the real world. It is perhaps because of such conclusions that you do not often find the principle that qualitative difference entails quantitative difference in philosophy textbooks.