What are the spatial and temporal dimensions, and what relation do they have to physical objects and events? Immanuel Kant (1724–1804) is one philosopher who believed that spacetime is an entity in its own right. That is, for him, spacetime is something like a giant container, which objects and events inhabit. By contrast, others believe that spacetime is not an object-like thing at all, but is rather nothing over and above the various relations that hold between objects and events.
In thinking about the humble hand, Kant devised an ingenious argument to support his view. Take a look at your hands. They both look exactly alike in very many ways: indeed, one is the mirror image of the other. However, there’s a difference between the two – and this we know because no way in which you could turn and rotate one would enable you to superimpose it onto the other (or to move it so that it would fill the exact same space the other currently fills). Now, imagine that the only thing in the universe was a human hand, attached to no body, simply suspended in space. The hand would need to be a left or a right one, but what gives it its leftness or its rightness? We cannot say that it is its relation to a human body – or indeed to any other object external to the hand – which makes it left if it is, or right if it is, for by hypothesis, it isn’t attached to a body and exists un-accompanied by any other object. Yet, it also cannot be anything internal to the hand which gives it its leftness or rightness because left and right hands are mirror images of each other: all of the relations of angle and distance between the parts of one hand are matched by those that hold between the parts of its mirror image. And since something must account for the particular leftness or rightness of the hand, Kant concludes that the only explanatory option left available is to say that it must be the relations the hand has to space itself which do this work. Since space can only do this work if it exists as a robust independently existing entity, then it really must be one! | |||