Biology

What is a function (of an object or an idea)? I once read that functions are conventional or "artificial". I can understand that an ashtray has its function (being a place to put cigarette ash) only if we assign it to it, but the function of our hearts (to pump blood) seems quite more natural.

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Some objects simply aquire a function in virtue of being used in a certain way, like the rock I use to prop open my office door. But traits of biological organisms do seem to have natural functions, like the white fur of the polar bear, whose function is camoflage. There is a spirited discussion among philosophers of biology over just how to analyse biological functions, but the selected effects account is perhaps the most popular. On this view, an effect of a biological trait is a function if the trait was selected for by natural selection because of that effect. Thus camoflage is a function of white fur because it is in virtue of that effect that polar bears came to have white fur. Notice that not all effects of biological traits qualify as functions on this account. The heart pumps blood, and that is presumably an effect that was selected for and so counts as a function. But the heart also produces that adorable lub-dub sound; that is just as much an effect of the heart, but presumably not the reason we have hearts, and so not a function of the heart.

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