personal identity

A Puzzle about Dementia


Dementia is one of the biggest challenges facing the British NHS, with one in three people developing the disease after the age of 65. This partly explains why there has been such excitement in scientific circles over intravenous immunoglobulin (IVIg), which appears to slow the rate of mental decline in sufferers from Alzheimer’s.

Obviously, from the societal point of view, dementia is a bad thing, and so this news is good. But from the personal point of view, should I be concerned about dementia – at least in its more severe forms? Epicurus famously claimed that we shouldn’t fear death, since when it arrives we won’t be around any more. Many seem to think the same about severe dementia, despite the fact that many – often the same people – also fear such a state.

Here’s how that view might arise. Imagine some extremely unpleasant experience, such as a very painful operation for which anaesthetic is for some reason unavailable. If you’re told you’re about to have such an operation, you will be very afraid, because you think the person under the knife will be you – it is you who will be feeling all that pain. But severe dementia can also be extremely unpleasant, so why isn’t it just like the operation?

There is one big difference. When the surgeon approaches you with her knife, you will have many of the same memories, beliefs, desires, and so on that you have right now. There will be a great deal of what Derek Parfit calls psychological connectedness and continuity between your mental states now and those you’ll have just before the operation. But that isn’t the case with dementia. You will have lost nearly all your memories, and so on. All that will be left is the capacity for conscious experience. And though that conscious experience might be deeply unpleasant, the line of thought goes, that doesn’t matter especially to you, since ‘you’ won’t be around any more, and there will be no important psychological continuity and connectedness between that individual and you now.

My own response to the prospect of dementia, however, is different. I can’t see why it matters very much whether, during the unpleasant experience, I have the same memories, beliefs, and so on that I do now. Consider the painful operation again. It might be so painful that you can’t *think* of anything else while it’s going on – so your memories, beliefs, and so on are entirely inaccessible. Does that somehow make it less bad? What I care about is what will be experienced by the capacity for consciousness I now possess, and if that capacity is going to be exercised in the future in such a way that there is consciousness of seriously unpleasant experiences – whether through some operation, or dementia – that concerns me now whatever memories, beliefs, and so on I am going to have, or indeed lack, in the future.