You develop a headache while working for hours at your computer. You stop, go into another room, and take two aspirins. After about 15 min, your headache has gone and you return to work. Can you infer...

You develop a headache while working for hours at your computer. You stop, go into another room, and take two aspirins. After about 15 min, your headache has gone and you return to work. Can you infer a definite causal relationship between taking the aspirin and curing the headache? If not, why not?