The distinction between innate and acquired traits is relevant to the long-standing debate between nativists and empiricists about whether knowledge (of concepts, of language, etc.) is primarily innate or acquired. The debate can’t get off the ground if the distinction is baseless or confused.
In recent years, some philosophers have indeed argued that the notion of innateness (and, therefore, the distinction between innate and acquired traits) is hopelessly naive, or even misleading, and should be abandoned. One reason is that one of its most common explications doesn’t work. Some people might think that being innate is the same as being caused or specified by genes. But being genetically caused is neither necessary nor sufficient for being innate. It’s insufficient because cases such as bacterial conjugation and genetic engineering show that genes can be acquired during the developmental process, which makes such genes and the traits they cause acquired. It’s unnecessary because there are innate traits, such as the cytoplasm and mitochondria, that are not genetic.
Another alleged reason to abandon the distinction is that causal claims about what’s innate and what’s acquired are often thought to be too obscure and context-relative to underwrite a robust distinction between innate and acquired traits. For instance, that A is taller than B might seem to be an innate difference if A and B had the exact same diets but different DNAs; however, that A is taller than C might seem to be an acquired difference if A and C had similar DNAs but different diets. Is height innate or acquired? Every biological trait is the result of many factors interacting in complex ways … Should we just abandon the distinction between innate and acquired traits?
No. The distinction between innate and acquired traits is as useful as ever. It tells us where and when we should intervene if we want to change a trait. Many scientists use it profitably, and so can we.
The first key is to follow what Judea Pearl sometimes calls the “causal revolution” that has changed the way many sciences work. There was a time when statisticians eschewed causal claims in favor of correlations. In recent decades, however, Pearl and many others have developed precise formal tools for assessing causal claims. This has made causal discovery more feasible and effective and, as a consequence, the notion of causation has become more legitimate in many sciences including but not limited to statistics.
The second key is to notice that what’s innate is what is either (i) already present within an organism at its origin, regardless of whether it is part of its DNA at any particular time, or (ii) caused by what was present within an organism at its origin. As far as I can tell, this simple account, which (a) corrects the traditional account of innateness as genetic specification and (b) builds on the causal revolution, avoids the pitfalls of traditional accounts of the innateness-acquired distinction.
One upshot is that claims about traits being innate or acquired are indeed somewhat context-sensitive, although we can also delineate normal contexts that make such claims nontrivial and interesting. Another upshot is that claims about what’s innate or acquired are best construed as graded claims: some traits are highly innate, others are highly acquired, and yet others are somewhere in between. Such claims can be made precise enough and tested empirically using the sorts of tools that people like Pearl have developed.[Many thanks to my co-author Robert Northcott for doing the heavy lifting on causation]