A famous statement by Carl Sagan suggested that extraordinary claims need to be backed by extraordinary evidence.1 It’s interesting to apply this claim to physicalist statements made about consciousness.
The primary claim is that consciousness results from only natural, physical processes. This explicitly rejects the possibility of any sort of supernatural cause, but also implicitly rejects anything outside of what is deemed to be a physical process, basically anything that might not fit in the current model of reality known as the “standard model”. All other science seems to fit within that model.
Now, consciousness is the most familiar thing to us that there is; it is the experience of our own existence. Because it is so familiar, it does not seem extraordinary. However, it should seem extraordinary if we take the position that everything is described by physical processes, because we know of nothing else that is even remotely like consciousness. No other observations of the natural, physical world are like it.
Observing consciousness in the midst of physical reality is like finding an antique model T crankshaft in a cooking store – it just doesn’t fit. Might there be some reasonable explanation for it that would make it fit in? Possibly, but it seems much more likely that it is from somewhere else. Making the assertion that it fits in is an extraordinary claim, one that needs to be backed up by much stronger evidence than we might use to justify the presence of a colander, for example.
To date, the only evidence we have to relate consciousness and physicality are things called Neural Correlates of Consciousness (“NCCs”). When some sort of conscious activity is observed, there is often a specific neural activity observed at the same time. But NCCs are simply observations of correlations; they do not mean that one causes the other.
This is often stated as “correlation does not imply causation”. For example, the fact that both ice cream sales and drownings are more common in summer does not mean that one causes the other. Similarly, just because a certain conscious event and a certain neural event happens at the same time doesn’t mean that one causes the other. It’s possible, perhaps even suggested, but not proven. And when the observations are as disparate as auto parts and cooking, we need pretty strong evidence.
This begs the question of what could possibly be an example of such extraordinary evidence?
Sometimes the way to approach such questions is through thought experiments. I’ll try to explore one such possibility in my next post.
- “Extraordinary claims require extraordinary evidence” was a phrase made popular by Carl Sagan who reworded Laplace’s principle, which says that “the weight of evidence for an extraordinary claim must be proportioned to its strangeness”. ↩︎
Kelvin's Clouds 