Laurence Steinberg, distinguished university professor of psychology at Temple University, is the co-author of “Rethinking Juvenile Justice” and director of the MacArthur Foundation Research Network on Adolescent Development and Juvenile Justice.

It’s important to note that this debate is not about whether juveniles should be excused from criminal responsibility. Juveniles know right from wrong, should be held responsible for their behavior and should face consequences when they violate the law. The question is whether the way we respond to a juvenile who commits a serious crime should differ from how we respond when the same crime is committed by an adult. I think so, for two reasons.

Because juveniles are more impetuous than adults, they are inherently less responsible for their acts, and are therefore less deserving of harsh punishment.

A bedrock principle of our criminal law is “penal proportionality” — that the extent to which people are punished should be tied to the degree of responsibility they had for the crime. This is why we punish premeditated crimes more harshly than impulsive ones and are more lenient in response to crimes that have been coerced than those that are completely voluntary. Because juveniles are more impetuous, short-sighted and susceptible to intimidation than adults, they are inherently less responsible for their acts, and are therefore less deserving of harsh punishment. Research on brain development helps explain the biological underpinnings of this immaturity, but neuroscience isn’t necessary to make the basic argument that adolescents are less mature than adults in ways that mitigate their culpability.

The second reason to sentence juveniles less harshly than adults is purely pragmatic. Most juvenile offending is transitory; only 10 percent of serious juvenile offenders become adult criminals. It is important to avoid responding to juveniles’ crimes in ways that will make them more likely to re-offend, as does incarceration in prison, a staggeringly expensive sanction that is ineffective beyond the period of incapacitation. (Few proponents of imprisoning juveniles consider what these individuals will be like when they are released back into the community, as the vast majority of them will be.) Moreover, there is no evidence that sentencing juveniles to prison deters other adolescents from committing crimes, because the same immaturity that leads teenagers to behave recklessly makes them unlikely to think far enough ahead to be deterred by the prospect of a serious punishment.