The Modest Interface: Adequacy as the Progressive Reduction of Illusion
We do not touch the universe by seeing it flawlessly, but by feeling exactly where it breaks our illusions.
There is a point where Kant, Spinoza, and modern neuroscience collide. And I think the collision teaches us something that none of them fully saw alone. If Spinoza is right in the simplest sense, then Proposition 18 assumes that we can increasingly understand reality itself. If Kant is right, then we never know reality as it is in itself. We know only reality as it appears through the forms of our cognition. If predictive processing is right, then the brain does not receive reality directly at all. It continually constructs hypotheses that are corrected by sensory input.
At first glance, Spinoza seems to lose. But he has not necessarily to. The mistake is to imagine that adequate means a God's-eye view. It cannot mean that. Not for a finite organism. Instead, adequate has to become a biological concept rather than a metaphysical one. Suppose you and I never see the world exactly as it is. Still, one of us predicts where the edge of the cliff is correctly. The other predicts it incorrectly. One survives. The other falls. Neither perceived the noumenon which is kant's name form real world. Yet one model was objectively better.
Why?
Because it tracked the causal structure of the environment more successfully. This is the crucial distinction. Reality-in-itself may remain inaccessible. But constraint is not inaccessible. Reality continually pushes back against our models. If I believe I can breathe underwater, reality corrects me. If I believe wolves are vegetarians, reality corrects me. If I believe trauma has no biological effects, reality corrects me. Reality is constantly saying "no" to bad models. Mostly it means eliminating those with bad models of rality.
Donald Hoffman argues that evolution did not shape perception to reveal objective reality. It shaped perception to support fitness. Yet even Hoffman does not conclude that anything goes. The interface must still preserve the structure needed for successful action. The icons on a computer desktop are not the transistors, but clicking the wrong icon still has predictable consequences because the interface is reliably connected to what lies beneath it.
This idea helps us avoid the trap of thinking we are completely isolated in our own minds which is solipsism. We can't directly compare our understanding of the world with reality from an outside perspective. Instead, reality constantly tests and chooses between different models of understanding. Evolution does this over many generations, while individuals learn throughout their lives. Science refines our knowledge over centuries, and trauma therapy helps people adjust their beliefs based on new experiences. None of these methods can fully grasp the true essence of reality, but they can all improve and make understanding more adequate.
Spinoza would probably accept the formulation that nobody can hate reality insofar as their models become increasingly constrained by reality itself rather than by fantasy, wishful thinking, or fear. Notice that we no longer say know reality as it is. We say allow reality to constrain your models. That is a much more modest claim. It also fits science. Science never proves that it has reached ultimate reality. Science constructs models that survive increasingly severe contact with reality. That is enough.
Finally, the fear of solipsism is exactly why Kant insisted that there is something outside us. We cannot know the noumenon directly, but it is precisely because something independent of us affects our sensibility that experience is not merely a dream. Likewise, predictive processing does not say that the brain invents the world. It says the brain invents hypotheses about a world that relentlessly corrects those hypotheses through prediction errors. The world is not inside your head. Your model is inside your head. The continual mismatch between the two is what drives learning.
Ironically, Spinoza's deepest insight survives this correction. The goal is not to escape the interface and become God, nor to achieve a view from nowhere. The goal is to make the interface less misleading. Adequacy is not perfect correspondence with reality-in-itself. It is the progressive reduction of error of our predictive model of reality under the pressure of a world that exists independently of our wishes. That is a goal that Spinoza, Kant, evolutionary biology, and predictive neuroscience can all support, even though they explain it in very different ways. The mind does not build reality, it builds guesses and survival belongs to the organism whose guesses match the sharp edges of the world.