5 Dispositions versus occurrences
Another important distinction to keep in mind is that between what philosophers call dispositions and what they call occurrences. A disposition is a tendency or propensity to manifest or exhibit something in certain circumstances. A wine glass, for example, has the dispositional property of brittleness: it will shatter into pieces when struck with enough force. But it need not ever actually shatter for it to possess the disposition of brittleness (it may be melted down into something else before it has a chance to shatter). Solubility and conductivity are other examples. Aspirins are soluble and copper wires conduct electricity – even though some aspirins will never make contact with water and even though not every copper wire will encounter an electric charge. The actual shattering of the wine glass, the dissolving of the aspirin, and the conducting of the copper wire, if such things end up happening, are all occurrences: they are events or processes that happen at certain times and have a certain continuous duration. The distinction between dispositions and occurrences applies also to mental phenomena, though not quite as straightforwardly as it does to glass, aspirin and copper. Many beliefs, for example, appear to be dispositional in nature, such as the belief that dogs are not explosive. Anyone who knows anything about dogs knows they are not explosive but the thought has probably never occurred to you before now. Nevertheless, that you did believe this before it occurred to you is clear from the fact that you have petted dogs without a second thought and this behaviour of yours was not considered reckless abandon. Many beliefs are like this: the belief that the chair you are sitting on will support your weight, or that the floor of your house will not cave in, that your car is not made of mud, that Descartes never met Darwin and so on. These beliefs are dispositional in the sense that they are not events or processes that we undergo; rather, they lead to or manifest themselves in the production of certain kinds of occurrences, such as the petting of dogs, the sitting on of chairs and the acknowledging of the fact that Descartes never met Darwin when confronted with it. Pain, nausea, being startled, perceiving and thinking are events or processes – occurrences – that we undergo.