IIn my two most recent posts (here and here) in this series on the science of purpose, I introduced the notion of intentionality as an intrinsic characteristic of living systems. Much has been written throughout the history of philosophy on what constitutes intentionality. Here I will discuss the key concepts essential to this subject.

One historically dominant position on intentionality has been the Brentano thesis, proffered by 19th-century German philosopher and psychologist Franz Brentano.  He maintained that it is intentionality which demarcates the psychic from the physical. The main competing position, held by Descartes, Locke, and others, identified consciousness as the essential criterion for separating mind from matter. In making the case for biologic intentionality, I will explain why it is most reasonable to side with Descartes rather than Brentano on this matter.

The Definition of Intentionality

What all philosophies agree on is that the definition of intentionality includes the act of directedness both about and toward something.  Now, according to the ontology of dispositionalism, all objects have intrinsic powers directed toward their characteristic manifestations. But the fundamental distinction between mental and inanimate directedness is this: for an entity to direct intention to something external, it must contain a representation of the object to which that intention is directed. Intention requires specific reference in order to have meaning. Thus, representational directedness fulfills the requirement that intentionality can only be explained within a theory of meaning, i.e., aboutness. 

It is easy to see how this applies to mental states, including desire, hunger, thirst, anger, kindness, etc. Quite in contrast, a wooden log directed towards combustion when put to flame requires no such internal reference for the combustion to occur. The same is true for all inanimate directedness, such as rainfall creating a watershed, magma generating a volcano, ozone absorbing ultraviolet radiation, helium lifting a balloon, CO₂ quenching a fire, etc.

Representational Directedness

But can there be unconscious or nonmental phenomena that do fulfill the above criteria for intentionality? I maintain that the answer to this question is resoundingly in the affirmative, based on the criterion set above (for intentionality), i.e., representational directedness.

Theoretical biologist Robert Rosen maintained within his revolutionary domain of relational biology that all organisms contain within themselves a representational model of both themselves and their environment. He presented anticipatory systems as exemplifying this concept.Examples in the biosphere abound.  Some of the more obvious include the cessation of photosynthesis in the leaves of angiosperms with shortening day length, the migratory behavior of birds, mammals, and insects pursuant to changing seasons, the hypergrowth of secondary sexual characteristics of all mating organisms antecedent to breeding, etc.

Biologic Intentionality

And the study of molecular biology reveals within a single cell an orchestration of biomolecular complexity far beyond anything in the macroscopic sphere. This well-demonstrated synchronized coordination can only take place by means of the representational directedness displayed by all the precisely interacting intracellular molecular components. And it was on this basis that I made the claim that intentionality exists within organisms independent of their mental state.  The term for this is (unconscious) biologic intentionality. 

There are countless examples available for illustration. We are all familiar with the normative language that describes such behavior regarding the transcription of DNA into RNA, the splicing of the RNA transcript, and its translation into a polypeptide. Another is to consider what is necessary to move glucose out of the plasma and into the cell, where life-giving metabolism can take place. Glucose is hydrophilic, thus unable to diffuse unaided through the hydrophobic cell membrane. That’s where insulin comes into play. Released from the pancreas in response to rising blood glucose levels, the insulin molecule attaches to an insulin receptor on the surface of a cell. Upon that interaction, that receptor sends a signal through the cell membrane to a set of proteins lying dormant underneath the cell membrane’s inner surface. When so stimulated, these previously inert proteins (Glut-4) assemble themselves into a cylinder which is then inserted through the cell membrane. This creates a pore through which only glucose can pass, allowing the glucose molecule to fuel the life of the cell. Representational directedness writ large.

The Impasse of Irreducible Complexity

Which takes us back to my advocacy for dispositional (powers) ontology. I have previously pointed out how dispositionalism overcomes the impasse of irreducible complexity inherent in Newtonian physicalism. And my goal with this discussion is to elucidate how this ontology allows us to entertain (unconscious) biologic intentionality, otherwise unreachable via Newton et al. Recall that dispositionalism simply says that all objects have properties that direct them to manifest their inherent power. Accordingly, I maintain the undeniable fact that the molecules of life have the property of intentionality which gives them the power to fulfill purpose. 

Life’s Designer

And where does biologic intentionality originate?

In order for nonmental, nonpsychic objects such as biomolecules to act with intentionality, there has to be a semantic representation built into the entire organism that directs the macromolecular interactions toward the operation of functions that fulfill purpose.  Acknowledging this constitutes another enormously powerful evidence for the reality of embedded design, which is absolutely necessary for the system to behave as it does.  And just like all conscious intentionality, biologic intentionality must ultimately derive from an intelligent source responsible for embedding the design within the organism and the biosphere. 

That conscious intelligence, the ultimate designer of life, was eloquently described by St. Thomas Aquinas as the unmoved mover, that which we call God.