I have read some philosophy of mind over the past couple of weeks and have come across some odd justificationist arguments. You know the ones I mean: ‘I can be certain that I think X’, or ‘When I am having a subjective sensation of seeing green my sensation cannot be doubted’, or ‘I can be certain that I am conscious.’ We might misremember a sensation or a thought or misinterpret it, but we had some sensation or thought and at the time there was no way we could doubt having it.
To be fair many justificationist philosophers of mind don’t endorse this sort of thing, but some do1 and I have occasionally heard them in other contexts so I think it’s worth my while to debunk them. One reply goes something like this: suppose there is a thermometer hanging up on the wall and the mercury is at the 23 degrees centigrade. Even if the room is not at that temperature, there is some fact of the matter about where the mercury is and the thermometer can’t doubt where the mercury is. I think this a weird way of putting things. For a start knowledge has to be knowledge of something other than the thing that supposedly instantiates the knowledge. Otherwise absolutely everything has indubitable knowledge and that’s a wrong headed idea. We attribute knowledge to something to explain its actions. Why does the mercury rise in the thermometer in a predictable when the room gets hotter? Moreover, there are lots of thermometers in the world and their readings will agree with one another to within some standard of accuracy if they are placed in the same situation. Things that are not thermometers will indicate temperature very inaccurately if they indicate it at all. The explanation of why thermometers act this way and other things don’t is that people designed the thermometers by a process of conjectures and criticisms. This feature makes them both useful and fallible: there are circumstances in which the knowledge instantiated in the thermometers will give the wrong result.
Also, this idea seems to involve drawing a sharp line between experiencing something and having an interpretation of it and that theory doesn’t seem tenable. How can we draw the line between seeing green and judging that we saw green and so on in any principled way? Or to put it another way, let’s suppose that there are miraculously infallible sensations or whatever. How can we tell them apart from our fallible judgements about them? And if we can’t what use are they?
Also, it seems to me there’s more than a touch of essentialism here. We define the ‘real sensations’ or the ‘real thoughts’ by a sort of verbal trick and this gives us knowledge. This sort of scholasticism is one reason why a lot of people dislike philosophy and it is due in large part to the pointless quest for justification. For what’s the point in doing this if you’re not desperate to find something you can justify? What problem does it solve?
1 See for example Tyler Burge’s paper ‘Individualism and Self-Knowledge’ in Journal of Philosophy, Vol. 85, pp. 649-663.