Hume says that causation is in the mind. It’s not objective but subjective. Humans attach cause to events when cause itself is not physically present.

When you first encounter that proposition you think it ridiculous because it goes so much against common sense. Of course there must be causes. But the more you understand David Hume the more you see his point. He says that causation is nothing more than the recognition of sequences - one thing followed by another and so on repetitively. When one particular event in experience is always seen to happen with another we believe a cause is present. For Hume that is an inference too far. There’s no empirical evidence for cause, only for repeated events which are, in his terms, “constantly conjoined”.

This philosophical problem is linked with induction. Induction is a kind of logical faith. You take evidence and from that evidence induce a conclusion. No matter how much evidence gathered Hume says there is always a leap of faith. We are not entitled, if rigorous reason is the standard, to make that leap logically and induce from any amount of particular events or sequences a generalisation.

So by this account it’s the mind that attributes cause to things. It is the mind’s tendency and character to make associations between things and connect them up. Whether causation exists externally in the world would need to be shown to have scientific validation. So far, as no one is said to have successfully answered Hume, the prospect for objective causation does not look good.

The philosophical problem has big implications for any serious ontology about the world which is why Hume has been at the top table of thinkers for generations past. He is likely to remain there.