The phrase "you are what you eat" has become drastically watered-down in contemporary American parlance. It is now more or less synonymous with "eat your vegetables."
But to materialist nineteenth-century thinkers, saying "you are what you eat" was like a call to arms against idealist mumbo-jumbo. "Mann ist was mann esst," went the play on words in German.
The idea was that even ideas themselves do not spring immaculately from an amorphous, pristine realm of spirit that humans access through their minds. Thoughts, the argument goes, are merely the by-products of purely physical processes, with each of us caught in an unbreakable causal chain.
Dostoevsky rightly railed against this type of deterministic, linear explanation of human behavior. For after all, to describe human actions as merely the inescapable consequences of external stimuli is to deny free will. Humans, in short, are not Pavlov's dogs.
From our 21st-century vantage point, however, it would be naive to deny that those external stimuli can play a powerful role in affecting decisions. As Al Gore pointed out in The Assault on Reason, there are numerous factors that can get in the way of rational decision making.
For legal decisions, the "legal realists" who came on the scene in the 1930s asserted that those factors often include a judge's personality. The notion was that "law is what the judge had for breakfast,"as one of my law professors put it to me at Valparaiso in the mid-80s.
I was reminded of this two weeks ago, when a newspaper columnist named Chuck Shepherd reported on a recently released research study of parole decisions. According to the lead researcher, Prof. Jonathan Levav of Columbia University, there are spikes in the granting of parole after lunch or snack breaks. But parole gets harder and harder to get as morning or afternoon sessions grind on.
Humans aren't Pavlov's dogs, but food does influence people's moods - and that cannot help but affect decisions at times. To say that isn't to accept hardcore nineteenth materialism; it's simply to acknowledge human limits.