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Hoffman's Conscious Realism:
A Critical Review

2. Fitness Beats Truth (FBT) Theorem

2.3 Reductio Ad Absurdum

Book cover: The Self and Its Brain: An Argument for Interactionism by Karl Popper and John C. Eccles

One way to view Hoffman's Fitness Beats Truth (FBT) Theorem critique of 'metaphysical realism', the view that there are mind-independent physical objects, is as a reductio ad absurdum form of argument. On this way of looking at Hoffman's approach, he is arguing that if the theory of evolution by natural selection is true, then nothing we perceive is veridical. A fundamental problem with this approach is that even if you assume it is true that all our perceptions are non-veridical, that fact would not entail that 'metaphysical realism' is false. That fact only entails that if such mind-independent objects exist, we can't faithfully sense their properties. As I have tried to show in this section, Hoffman's argument, in fact, presupposes the existence of such mind-independent objects for it to work; that is, just those objects that provide the selective pressures for fitness to evolve and to evolve in.

As a reductio ad absurdum, Hoffman needs the argument to stop at proving the absurdity of belief in the veridicality of perception. But even here, it does not do the work of disproving 'metaphysical realism'. Unfortunately for Hoffman, taking his reductio ad absurdum to its natural conclusion, it undercuts the very theory of evolution that he relies on to show that our perceptions are non-veridical.

As a further illustration of this point, consider Hoffman et al's description of the requirements for setting up and testing their FBT Theorem using computer simulations:

... we must include strategies that see none of the true facts, some of the true facts, and all of the true facts. Even if we suppose that human perception is veridical today, we must consider all possible strategies, veridical or not, in order to explore the plausible hypothesis that we evolved from species whose perceptions were not veridical.

[Hoffman et al 2015a: 1482]

In this scenario, it is Hoffman and his collaborators who are evaluating whether the test subjects see the 'true facts' or not. Hoffman, though, is a member of the species H. sapiens, a species he says for whom today 'none of our perceptual experiences are literally true of the world' [Hoffman et al 2015a: 1489]. Again, his own thesis is reduced to a reductio ad absurdum.

I want to dig down a little deeper here with a couple of specific examples illustrating the absurdity of Hoffman's position. Consider again Hoffman's case study using an organism's perception of the quantity of a resource [Hoffman et al 2015a: 1486]. In their simulation, an organism employing the critical realist (veridical) strategy is pitted against an organism using the interface (non-veridical) strategy. Both types of organism perceive a variable quantity of resource using just four colours. I've reproduced Hoffman et al's illustration below (labelled Fig. 2 and Fig. 3 in Hoffman et al). One such resource is water. Now picture yourself sitting in front of a very large transparent tank that is being gravity-filled with water at a constant rate. We know that the tank is being filled at a constant rate because the force of gravity is constant and the water is being fed through a fixed diameter tube.

Hoffman's diagrams for plotting payoff vs resource quantity for critical realist and interface strategies

Now Hoffman would have us believe that although the volume of water in the tank appears to be increasing, it may in fact not be so. For Hoffman, when the tank appears to us human beings using the non-veridical interface strategy as being two thirds full, it could in reality be one third full or it could be two thirds full (green bands in Fig. 3). You just don't know. The quantity you think you are perceiving is a 'you know not what'. Even more absurd, for Hoffman, when you perceive the tank as empty, it could in reality be full (red bands in Fig. 3).

Hoffman then applies this absurd conclusion to all of the other properties we sense. These include temperature, shape, velocity, hardness, and so on. If we cannot in reality determine the scalar quantities of these properties, then how do Hoffman and other scientists practice science? If a hydrologist measures the volume of water as, say, 70 cubic litres, and we believe Hoffman, the volume could be anything. It could be one cubic litre or it could be 1000 cubic litres. We just don't know. How then can we support a science of hydrology, or cosmology or biology at all?

Now, if Hoffman and other scientists can't say anything about the properties of biological organisms and the environments in which they live, then what are we to make of the entities that populate all versions of evolutionary theory? If cells, DNA, enzymes, fossils, mating pairs, predators, food, water, and so on, are all 'you know not what', if they are all non-veridical 'icons' representing 'you know not what' properties, then Hoffman needs to tell us how we can construct a theory of evolution in the first place. Hoffman appears to hoist himself on his own petard. Alternatively, if he insists on using the science of evolutionary biology to mount his case, he has already rejected the proposition that all perceptions are non-veridical. These are the horns of the dilemma that Hoffman is cast upon.

Book cover: An Idealist View of Life by  S. Radhakrishnan

How did Hoffman get to this point of absurdity? One reason is that his research team's mathematical model is based on a highly simplified organism that experiences only four possible percepts representing a wide scalar range of resource quantities. Hoffman mentions one such resource that organisms need to survive: 'Not enough water and one dies of thirst; too much and one drowns; somewhere in between is just right' [Hoffman et al 2015a: 1486]. This is the kind of organism that would have first evolved some billions of years ago. Now compare that perceptual capacity to that of Homo sapiens today.

Hoffman assumes here without argument that the simple organism employing the useful strict interface strategy and with a capacity for only four percepts will remain unchanged over the subsequent billions of years of evolution. Contrast that simple organism with a current Homo sapiens' brain containing some 80 billion neurons with some 100 trillion connections between them. We are able to discern by several orders of magnitude more differences of quantities of water than just four. Hoffman's assumption that his team's highly simplistic mathematical simulation incorporates all of the strategy generation and selection forces guiding evolution throughout the last few billion years seems entirely fanciful.

In a later paper, Hoffman [2009: 20] recognizes the simplicity of a similar mathematical model and suggests how the models may be developed to more accurately reflect natural ecosystems. At one point, tellingly, he opines that these more complex models will allow scientists to determine at what level of complexity a truth strategy will prove more advantageous than a simple interface strategy. He bets, however, that there will be none of interest. For Hoffman, the jury is still out on this crucial question. In view of how this admission severely limits the confidence in his bold conclusions, Hoffman does not tell us his reasons for betting against what I would have thought the more reasonable outcome.

A second reason Hoffman got to this point of absurdity is that he and his team's mathematical model premises a direct relation between perception and action. This direct relationship was true for the earliest and simplest organisms in our evolutionary history. However, it is clear that during the long evolutionary process, this basic stimulus-response function was complemented with both an environment modelling function and an executive function. So, today, when we are hungry and sense an apple, we can decide to eat it now or later. Our decision depends both on the model of the external world we construct and on our desires and values. If our belief is that eating the apple will raise the chagrin of the person who owns it, we may decide not to eat it all. Now, none of these complexities about our biological capacities and their evolutionary origins figures in Hoffman's mathematical model. He simply assumes, against the evidence, that if organisms were simple one-directional stimulus-response mechanisms billions of years ago, they must essentially be the same now. In an informative paper, Vlerick [2014] has more to say on the complexities of our cognitive capacities and their evolution.

Copyright © 2020, 2022

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