Causality. It is a funny thing. Or not so funny.
A few years back, I took my class, as a teacher, on a class trip to the Historic Dockyard in the naval city of Portsmouth, UK. My school is some 45 minutes walk and a short ferry ride from there. With the cost of coaches, it is important to be able to walk to such places to keep the costs down for parents.
We pasted it there on the way, and we were running a little behind, so the walk back at the end of the day was quicker still. One of our parents, helping with the trip, was a heavy smoker who had to stop off at strategic times throughout the day for a crafty kids-can’t-see-me smoke. Many of the children were moaning on the way back because they simply were not used to walking any such length of time. This certainly applied to some of the parent helpers too.
Anyway, we made it back for the end of the school day, so good effort.
Except, that night, we heard that the aforementioned parent helper had died. He had had a heart attack.
Ever since that moment, I have felt partly responsible for that outcome, of that man’s death. In a naive, folk understanding sort of way, that is.
In writing my book on free will, and in researching the Kalam Cosmological Argument, I have come to understand that causality is much more complex than one might imagine. A does not cause B which causes C in such a simplistic manner. At best, things are only ever contributory causes (see JL Mackie’s INUS notion of causality ); but even then, this assumes one can quantise time, and arbitrarily assign discrete units of existence to both events and entities.
Let’s look at the event of the class trip. Did it start when we arrived at the dockyard, when we got off the ferry, when we left, when I started organising it, or, indeed, were elements of the trip in place when I started planning the unit, given the job, got my teacher’s qualifications etc?
Of course, there is no objective answer to that. These abstract labels are subjectively assigned such that we can all disagree on them. That is, simplistically speaking, an element of conceptual nominalism. Likewise, there were necessary conditions in the parent’s life which contributed to his death: anything from his smoking, to his lack of general health, from deciding to come on the school trip, to deciding to get married and have kids. And so on.
An event happens in time and arbitrarily ascribing a beginning and an end to that event is an abstract pastime, and thus fails to be (imho) objectively and (Platonically) real.
Causality works through people, and harnessing it so that any one individual can claim themselves (morally) responsible for future effects which themselves are caused by effects preceding the individual makes for tricky philosophy. This is the battleground for the free will debate, for sure. Arbitrarily cutting causality up in such a way is problematic.
As I have set out in my analyses of the Kalam Cosmological Argument (KCA), which I hope to turn into a book (based on a university thesis I did on it), causality is not a linear affair which can be sliced and diced, It is a unitary matrix which derives from either a single beginning (like the Big Bang), something I find problematic, or eternally backward, or reaching some time commencement which could itself be a reboot. Either way, the idea of causality cannot be seen, and should not therefore be seen, in a discrete manner of units which can be attributed to equally problematic notions of events or unities. We are one big family of causality, this here universe.
So, in answer to the question, no. No, I didn’t kill anyone. Perhaps we could say that the universe did. And whatever notion “I” am, and whatever “I” am represented by, sat on or, better still, was part of the threads which cross and recross intricately and almost infinitely over each other in a mazy web of interconnected causality.
 Cause as INUS-condition. The most sophisticated version of the necessary and/or sufficient conditions approach is probably John Mackie’s analysis of causes in terms of so-called INUS conditions. Mackie suggested that a cause of some particular event is “an insufficient but non-redundant part of a condition which is itself unnecessary but sufficient for the result” (Mackie 1974: 62). Mackie called a condition of this kind an INUS condition, after the initial letters of the main words used in the definition. Thus, when experts declare a short-circuit to be the cause of fire, they “are saying in effect that the short-circuit is a condition of this sort, that it occurred, that the other conditions which, conjoined with it, form a sufficient condition were also present, and that no other sufficient condition of the house’s catching fire was present on this occasion” (Mackie  1993: 34). Thus, Mackie’s view may be expressed roughly in the following definition of ‘cause:’ an event A is the cause of an event B if A is a non-redundant part of a complex condition C, which, though sufficient, is not necessary for the effect (B). Source.