" What do philosophers mean when they say something is ‘metaphysically possible.’ Why don’t they just simply say ‘possible’?

Metaphysical possibility is one way of thinking about the possibility of something being the case, a way that is often of special relevance to philosophers. If you think about it, we often use the phrase ‘x is possible’ in a variety of ways. We might speculate what is possible given the state of our knowledge—we might say in a hopeful tone of voice ‘I think it is possible there is some pizza still left in the fridge.’ What we usually mean is that we don’t have any knowledge, which forces us to conclude the depressing fact that all the pizza has been eaten. It is possible, because we are ignorant of the opposing state of affairs—we don’t know if our greedy housemates have eaten the pizza.

However, philosophers are often interested in talking about possibility in a way which is not dependent on what is possible given the state of an agent’s knowledge, but rather what can possibly be true given the state of the world, or other possible worlds. When philosophers ask questions like ‘is it possible my mind could exist without my body?’ these are often thought to be questions about what is metaphysically possible. But we don’t need to look for fancy philosophical examples to understand what metaphysical possibility is, because many philosophers will suggest that we use this sort of ‘metaphysical possibility’ in our daily knowledge claims all the time. Think about what we mean when we say, ‘Chelsea won last night, but it is possible Everton could have.’ We are not saying that we are ignorant of the result, we know who won the match last night. We do not think it is possible for Everton to have won, because we are ignorant of the fact they lost. Nonetheless, we might think there is another possible world or state of affairs in which Everton won rather than Chelsea. Therefore, we might think the proposition ‘it is possible Everton could have won’ is true. It is these sorts of claims that philosophers are interested in when they use the term ‘metaphysically possible.’