The Expression of Emotion: Designed Showing or Inclusive Indicating?

Every time we feel a strong emotion, our bodies often react in ways that others can see. A smile spreads across a face when we are happy; a frown tightens when we are angry; tears fall when we are sad. For centuries, philosophers and scientists have asked a simple but deep question: what exactly makes these reactions count as "expressions" of emotion? Is it enough that a behavior gives a clue about how someone feels, or does it require something more? To answer this, researchers must distinguish between a mere hint and a deliberate message. A hint is like a footprint in the mud that tells a tracker someone passed by; the person who made the footprint did not intend to leave a message, but the information is there. A message, by contrast, is like a signpost placed specifically to tell travelers which way to go. The debate centers on whether human emotional expressions are mostly like footprints, left over from other biological functions, or if they are like signposts, evolved specifically to communicate our inner states to others.

A new paper by Trip Glazer, a philosopher at the University of Dayton, enters this long-standing debate by revisiting the arguments of Charles Darwin. Glazer examines a recent theory proposed by Jay Odenbaugh, who argues that for a behavior to truly count as an emotional expression, it must be a "designed showing." This means the behavior must have been created by evolution or intention specifically to send a message, and it must successfully allow an observer to know what the person is feeling. Odenbaugh believes this strict definition is necessary to make sense of how we communicate. However, Glazer suggests that this view is too narrow. He argues that Odenbaugh should instead adopt the broader, more inclusive definition that Charles Darwin originally proposed. According to Darwin, an expression is simply any behavior that provides information about an emotion, regardless of whether it was designed to do so or whether it guarantees that the observer understands it.

Glazer's paper carefully unpacks these two competing ideas. He explains that Odenbaugh's view relies on the idea that expressions are "signals." In the natural world, a signal is a trait that evolved specifically to convey information, much like a bird's warning call that is designed to tell predators, "I see you, so do not bother chasing me." Odenbaugh insists that for a smile or a cry to be a true expression, it must be this kind of signal, and it must also "show" the emotion, meaning it must give the observer enough evidence to truly know what is happening. If a person smiles but is actually faking it, or if a person blushes because of a hot room rather than embarrassment, Odenbaugh's theory would say these are not true expressions because they fail to meet the strict criteria of being designed to communicate and successfully showing the truth.

Glazer challenges this by returning to Darwin's original work, The Expression of the Emotions in Man and Animals. Darwin argued that many behaviors we call expressions were not originally designed to communicate at all. Instead, they are side effects of other bodily processes. For example, a person might stomp their foot when angry because the body is full of energy and needs to move, not because they are trying to tell someone they are angry. Over time, observers learn to associate the stomp with anger, but the stomp itself was not created by evolution to send that message. Darwin called these "cues" rather than signals. Glazer points out that Darwin's definition is much more inclusive: it counts any behavior that indicates an emotion, whether it is a deliberate signal, a side effect, or even a fake attempt that fails to convince anyone. Glazer argues that this broader view fits better with our modern understanding of evolution and that it captures the messy reality of how humans and animals actually behave.

The paper also addresses a common objection: if we accept this broad definition, do we lose the ability to distinguish between telling someone how we feel and showing them? Glazer suggests we do not. We can still recognize that some behaviors are deliberate messages while others are accidental clues, but we do not need to exclude the accidental clues from the category of "expression." He notes that other researchers, such as Andrea Scarantino, have reached similar conclusions, arguing that we should define expression based on whether a behavior provides evidence of an emotion, rather than whether it was designed to do so. Glazer concludes that Odenbaugh's strict "designed showing" theory excludes too many real-world behaviors that we naturally recognize as expressions. By adopting Darwin's "inclusive indicating" approach, we can build a theory of emotion that is both scientifically accurate and true to the full range of human experience. The paper does not claim to have solved every mystery of emotion, but it offers a strong case for widening our definition to include the full spectrum of how feelings become visible.