Reid lays out three requirements for causation and argues that only an agent can be a true cause. He emphasizes the ambivalent capacities, free will, and moral responsibility of agents, and explains human behavior and moral responsibility through empirical evidence of causation and the role of motivation.
Suppose a red ball hits a stationary white ball, causing the white ball to move. Hume laid out three requirements for a causal relationship between the red ball hitting the white ball and the white ball moving. The cause must precede the effect in time, the cause and effect must follow each other in space and time, and there must be an “invariant union” between the cause and effect. An invariant connection means that if the balls move in the same way and collide in a similar situation, they will behave in the same way. However, Reid believed that even when Hume’s three conditions are met, such as in the example above, causation is not established: only an agent with free will can be the cause.
In his theory of agent causation, Reid characterized a cause as an entity that has an “ambivalent capacity” and is responsible for the change. An ambivalent capacity is an active ability to produce or not produce a change, and an agent is an entity that possesses the capacity to produce an effect, can exercise that capacity, and can be held responsible for that change. Reid argues that the true cause is the actor. According to him, when a red ball hits a white ball, the white ball can only move, not be moved, so the red ball cannot be an agent.
Reid also emphasized empirical evidence for causation. In his view, causality should be based on actual experience, not just logical reasoning. For example, if repeated experiments always show the same result under certain conditions, then only then can we be sure of a causal relationship. However, this empirical evidence can be understood on a different level than the free will of the actor. This is because free will is an internal decision that cannot be observed empirically.
From Reid’s perspective as an empiricist, the only agents within the scope of observation are humans. If a person rolls a red ball to make a white ball move, and the white ball moves, then the person is the agent and the movement of the white ball is the result. In Reid’s view, for an outcome to occur, the agent must be ambivalent, and the agent’s motivations must always be in sync. Reid viewed volition as an event in the mind. In this regard, it can be argued that the volition that is coupled to the exercise of an ambivalent faculty that produces an outcome is the manifestation of another ambivalent faculty, which requires another volition. In response to this argument, Reid sees an intrinsic activity of the mind, such as the will, as indistinguishable from the exercise of the agent’s ambivalent faculty, the “causing of the will,” and the result, the will itself. This suggests that in the case of motivation, the exercise of the agent’s faculties is itself motivation, and does not require another motivation.
Reid also developed an in-depth discussion of human moral responsibility, arguing that the reason humans can be held accountable for their actions is because they have free will. This free will allows humans to determine their own actions, and thus makes them morally responsible for the consequences of their actions. This emphasized that human behavior must be understood in a moral and ethical context, beyond mere physical cause and effect.
However, it could be argued against Reid’s view that intentions and events are always conjoined that it is the intention that causes the event, not the actor. In response, Reid supported his theory by arguing that the invariant union alone does not justify causal inevitability. While emphasizing the role of intention, Reid argued that the mere existence of intention is not enough. In fact, it is only when the motivation is manifested in an action, and the action leads to an effect, that causality is established.
Reid also had to address the problem of “opportunistic causes. At the time, some philosophers, influenced by medieval philosophy, believed that only God was the true cause of events, including human behavior, and that agents were merely chance causes. Opportunistic causes are things that routinely appear to be causes, but are not actually true causes. Reid rejected this position in favor of empiricism. He argued that God cannot be the true cause of events because all we can experience are the motivations and actions of agents, and divine intervention in actions is something we cannot experience. Reid emphasized the implications of human agency by arguing that it is ultimately up to the agent to make decisions.
Reid also addressed philosophical issues related to the moral responsibility of agents. He believed that moral responsibility is not simply determined by external conditions, but by the free will and choice of the actor. This means that humans can control their own behavior and are therefore morally responsible for the consequences of their actions. Reid’s argument provided an important foundation for modern ethics, which emphasizes human moral autonomy and responsibility.
Reid’s theory challenged traditional understandings of cause and effect, emphasizing the importance of agents and free will. This has important implications for understanding human behavior and moral responsibility, not just for explaining events in the physical world.
