On The Nature of Causation and Identity
Hume, in his Enquiry Concerning Human Understanding, tells us that our ideas originate in things that we observe or experience. All ideas can be simplified to the point where they can no longer be reduced or defined; causation is one of these ideas. The only way to define these ideas any further is to look to the external source of these ideas. However, we notice the natural events that we call causal do not actually display this trait of causation. It would therefore appear that causation is not something that we can observe, but rather is something that we invent and project onto nature in order to explain certain patterns. However, failing to find causation in the places we would first think to look for it does not necessarily entail that we cannot find examples of causation. One such example, which is readily accessible to us, is our causal view of our identities, and using this example we can establish the existence of causation.
Certain ideas are so fundamental to our thoughts that they shape the way we view the world. One such view is that of the causal connection between events in the natural world. Hume defines these ideas as those, “…when we have pushed up definitions to the simplest ideas, and find still more ambiguity and obscurity…” (Enquiry, VII, 1). In other words, these ideas are those, which we cannot reduce to more basic definitional components. When we reach these ideas, we must ask how we can examine them. Hume posits “…that it is impossible for us to think of anything, which we have not antecedently felt, either by our external or internal senses.” (Enquiry, VII, 1) This means that all of our ideas are those things that are first experienced outside of us, and then internalized. Because of this, Hume says that the way we should go about understanding causation is to look to those things in nature that display cause and effect.
Where does causation come from?
We witness related events all the time. We will see a stationary billiard ball struck and then begin to move, or we will see lightning hit a tree and the tree will burst into flame. The aforementioned instances (and many others) form the basis for our view of causation. When we see these events happening in such proximity and with such regularity, we begin to say that A causes B. However, what do we really witness when we see these two events?
When the billiard ball is struck and then begins to move, we are witnessing two separate events: the event of the billiard ball being struck, and then the event of the billiard ball moving away. There is nothing that suggests that the two events are necessarily connected to one another, aside from the regularity of the connection. If in fact we had only observed the two proximate events once, we might never give the idea of a causal relationship a second thought. Causation starts to enter the picture when we repeatedly observe one event (or several events) following from a first event. However, nothing fundamentally changes between the first time and the hundredth time we observe the two events. The addition of causation is something not that we observe from the events, but rather something that we make up to explain why two or more events occur in such proximity and with such frequency. When we make the claim that ‘A causes B’, what we are really saying is that ‘when I regularly observe event A, event B follows shortly thereafter’. Causation is something that we make up in order to explain the regularity of this correlation; we then project this notion of causation onto nature[1]. This does not necessarily mean that causation does not exist, but it means that we do not observe it in what we usually think of as causal relations.
Apodictic vs. Empiric Truths
Hume believed in apodictic truths, which is to say he believed it impossible to know anything that is dependent upon contingent knowledge. The only things we truly know are those things that are necessarily true, and not merely contingently true. By this definition of knowledge, we know that the sum of the interior angles of a triangle will add up to 180 degrees, but we do not know that the sun will rise tomorrow. It is with this in mind that we draw the crucial distinction for Hume when he talks about causation. When we repeatedly witness temporally related events, we are not actually witnessing a connection between the two events to the point where we know ‘A causes B’. Rather, we come to expect the second event to follow after the first. Because we have not actually observed a reason for a necessary connection between the two events, we do not know that one exists.
Continuity & Identity
The question remains as to whether or not we actually experience causation in such a way as to adequately explain our idea of causation. Hume correctly pointed out that we do not observe causation in the natural world (Enquiry, VII, 1), but that is not to say that we do not experience causation. Humans live in four dimensions; meaning not only are we extended in space, but that we are also extended in time. Just as we have a feeling of connection between our bodies and arms, or with our hands or fingers, so do we have a feeling of connection between our past, present and future selves. We experience this causal connection, in that I know that my identity today is connected to, and dependent upon, my identity yesterday. Furthermore, we know that actions or decisions made in the present have a direct causal relationship with ourselves in the future. It is this internal experience of causation that provides the basis for our ideas of causation. It may be the case that this idea of causation is then projected onto temporally connected events we observe in nature. Regardless, unlike these natural occurrences, the sensation of the continuity of our identity across time necessarily leads to an experience of causation. It is these sensations that allow us to conclude that causation exists, and provide meaning to the term.
We therefore have a mechanism by which we can explain the existence of a causal connection that we do not seem to observe or experience in nature. This internal experience is what provides meaning to our idea of causation. This is not to say that causation does not exist in nature; merely that we do not observe it. Furthermore, the sense of causation obtained internally is not contingent, as are natural events. Whereas the sun not rising tomorrow might be highly unlikely, it is not absurd to imagine the possibility. Conversely, it is absurd to imagine that we could obtain any cohesive amount of identity should our identity not be necessarily causally dependent over time.
[1] In a way, this bears similarity to the phenomenon of pareidolia, in which humans see patterns or non-existent forms in randomness. Humans are excellent at ascribing patterns to things and occasionally we go too far and start seeing patterns where they do not exist. Examples of pareidolia include people seeing Jesus in their toast, faces on mars, or the famous
Rorschach inkblot test. It is also interesting to note that Carl Sagan hypothesized that we see these patterns because of our survival instincts; and specifically that the human brain is hard-wired from birth to view the human face. (Sagan, Carl (1995). The Demon-Haunted World – Science as a Candle in the Dark. New York: Random House. ISBN 0-394-53512-X.) Similarly, causation is fundamental to the way we behave and view the world. Such a thing could be hard-wired into the brain, because of the survival benefits of viewing the world through a causal lens.
