What is the difference between weak emergentism and strong emergentism?

Weak emergentism and strong emergentism are two distinct positions within the philosophy of mind that attempt to explain the relationship between mental phenomena and physical processes. While both positions acknowledge the existence of emergent properties, they differ in their understanding of the nature and causal powers of these emergent properties.

Weak emergentism posits that mental properties emerge from physical properties, but they do not possess any causal powers that are independent of the underlying physical processes. According to this view, mental phenomena are reducible to and supervene upon physical phenomena, meaning that mental states are determined by and dependent on the physical states of the brain. Weak emergentists argue that mental properties arise from complex interactions of physical entities, such as neurons, but they do not introduce any new causal powers beyond what is already present in the physical realm. In other words, mental properties are considered to be epiphenomenal or secondary to the physical processes that give rise to them.

On the other hand, strong emergentism posits that mental properties not only emerge from physical properties but also possess novel causal powers that cannot be reduced to or explained solely by the underlying physical processes. According to this view, mental phenomena have a level of autonomy and can exert causal influence on physical processes. Strong emergentists argue that mental properties are irreducible and cannot be fully explained by the laws of physics or any other physical sciences. They believe that mental properties are ontologically distinct from physical properties and cannot be reduced to them.

In summary, the main difference between weak emergentism and strong emergentism lies in their understanding of the causal powers of emergent mental properties. Weak emergentism suggests that mental properties are dependent on and reducible to physical properties, while strong emergentism posits that mental properties have novel causal powers that cannot be fully explained by physical processes alone.