Is the Tomato a Fruit? Well, It Depends…

Most of us have encountered the oft-repeated question “Is the tomato a fruit?” or the similar question “Is the tomato a fruit or a vegetable?” These two questions appear to be nearly identical, and yet they are actually quite different. The best answer to the first question is “Yes, the tomato is a fruit.” But the best answer to the second question is “The tomato is a vegetable.” So how can these two apparently contradictory answers both be correct?

The first question — “Is the tomato a fruit?” — is a great example of misdirection. It appears that the question is about tomatoes, but in fact, everyone agrees on what a tomato is. You never hear an argument about whether or not a particular object is a tomato. It’s the word “fruit” that is the source of the disagreement. If we all agreed on a precise definition for the word “fruit”, then there would be little room left for debate about whether a tomato fits the definition. This is the very essence of what is called a semantic argument, where the entire discussion hinges upon the meaning of a particular word — and in this case the word is “fruit”.

Semantic arguments are quite common, and can go on and on for ages without a genuine resolution. This can seem bizarre to an independent observer, who might be thinking “Just look the word up in a dictionary, people!” However, there are two principal limitations to this kind of solution:

1. People don’t usually think this way. Our brains are wired to create generalizations from examples. From the time we were tiny kids, we have heard people using the word “fruit” in the context of examples — such apples, bananas, oranges, strawberries, and grapes — but seldom if ever defining the word. And that is perfectly fine with us. We quickly developed an intuitive sense for the meaning of the word, without ever consulting a definition. We are quite comfortable with fuzzy abstractions like this, deducing the meaning of a word from examples. In fact, people were using words such as “fruit” for millennia before anyone decided to create a dictionary of precise definitions for our words.

2. When we consult a dictionary for a particular word, we often find multiple definitions. In part, this is because the meanings of words change over time, and because we often use words as analogies to their earlier meanings. If we say that someone is “enjoying the fruit of his labors”, then we clearly understand that the conversation is not about apples and oranges. Words can also acquire special meanings that are unique to a particular field or profession — such as law or medicine. Science in particular has appropriated many common words and given them specific meanings that deviate from the fuzzier meanings employed by the general public. The upshot is that we often need to consider the context in which the word has been used in order to choose the appropriate definition from a dictionary.

By following the first approach — to deduce a meaning from generalization — our abstraction of the word “fruit” can take us in several possible directions. For many of us, when we hear the word “fruit”, we think of plant material that is sweet, juicy, and deliciously edible. But another abstraction is to think of “fruit” as a result or product of an effort — just as a fruit can be considered the product of a tree or plant. Therefore we can talk about the fruits of someone’s efforts, or underwear as “Fruit of the Loom”, or a baby as “the fruit of thy womb” (in the prayer “Hail Mary”).

Botany, the scientific study of plants, has taken the abstraction of the word “fruit” in still another direction. In botany, the essential attribute of a fruit is that it contains seeds. In some ways, this does not surprise us. We are accustomed to finding seeds in apples, oranges, watermelons, and so on. But in botany, this is the principal defining attribute of a fruit, which can lead us to some non-intuitive conclusions.

Technically, the botanical term “fruit” refers to the maturing ovary of a flowering plant. This is the part of the plant that might contain seeds, provided that the ovules inside the ovary have been fertilized with pollen. By this definition, a tomato is certainly a fruit, along with apples, oranges, bananas, grapes, cherries, peaches, watermelons, and so on. But in the scientific domain (that is, in the field of botany), the term “fruit” has a much broader meaning than in popular speech. To a botanist, a cucumber is also a fruit, and so is a green bean, a pea pod, an avocado, a zucchini, a pumpkin, an eggplant, and a bell pepper. In fact, nearly all flowering plants bear fruits of one kind or another, most of which we would never consider eating. The husk of a coconut is a fruit, and so is a beggar’s tick — that annoying thing that clings to your clothes when you go hiking. Furthermore, our intuitive idea of a fruit is that it has some pulp or flesh surrounding the seeds, but a botanical fruit need not have such flesh. In fact, a single-seeded fruit that lacks pulp can appear to be a naked seed without any fruit at all. Such fruits include a sunflower seed, an acorn, or the winged seed of a maple tree.

So if we ask “Is the tomato a fruit?”, then it makes sense to answer “yes”, because botanically a tomato is indeed a fruit. It wouldn’t make much sense to answer “no”.

On the other hand, the question “Is the tomato a fruit or a vegetable?” takes us down a different path. Although the word “fruit” is commonly used in science, the word “vegetable” is not. In older literature, the word was essentially a synonym for “plant”, and therefore “vegetable matter” meant (and still means) any kind of material taken from a plant. But in modern science the word is seldom used, and it is not associated with any essential scientific concept.

Therefore the question “Is the tomato a fruit or a vegetable?” puts us into a different domain — a domain where the term “vegetable” is still in current use — and that domain is food preparation. Furthermore, this question presents the terms “fruit” and “vegetable” as a dichotomy, where fruits and vegetables are mutually exclusive sets — and therefore the tomato can be a member of just one of these sets. This particular use of these terms is quite common, reflecting a popular way of thinking about food plants. This is a perfectly valid usage of the words, but it does not correspond to any professional field — such as botany, medicine, or law — where all of the jargon is carefully defined. Instead, we must rely on cultural rules of thumb to distinguish between fruits and vegetables.

A key point to note is this: Virtually no one ever asks “Is the zucchini a fruit or a vegetable?” or “Are green beans fruits or vegetables?” Most people would consider these to be silly questions, replying “Zucchinis and green beans are obviously vegetables!” And yet both, from a strictly botanical point of view, are fruits. This indicates that there is something different about tomatoes — something that makes the answer less obvious. The issue is that our process of mental categorization often employs several simultaneous criteria. When we look at a tomato, we see a food item that is usually prepared “like a vegetable”. But we also see an object whose shape and color are both “fruit-like”. Furthermore, a tomato is juicy like a fruit. And while a tomato is only slightly sweet, it is usually tart, another characteristic that is far more common in fruits than in vegetables. Therefore we have many possible characteristics to consider. So is there any single characteristic that can serve as a reliable rule of thumb to distinguish a fruit from a vegetable?

There are several possible criteria that might come to mind, but the most reliable rule of thumb is based on the finished food item. If you start with a recognizable part of a plant (not a plant by-product, such as sugar or flour), then the nature of the finished food usually indicates whether that piece of plant is considered to be a fruit or a vegetable. If the plant material is typically used as a major ingredient in sweet dishes, especially if served as a dessert, then it is usually considered to be a fruit. But if the plant material is typically used in savory dishes (that is, salted instead of sweetened), then the plant material is usually considered to be a vegetable.

But what if the plant material is eaten fresh and raw, without any preparation other than cutting it up? A raw apple is clearly a fruit, and a raw celery stalk is clearly a vegetable — so what is the formal distinction? The sweet and salty distinction can still apply. The foods we consider fruits are usually sweet (and often tart at the same time), and if we have a choice of sprinkling on sugar or salt, then we’ll usually go for the sugar. The foods we consider vegetables are usually not sweet (and usually not tart either), and if we have a choice of sprinkling on sugar or salt, then we’ll usually go for the salt.

By this culinary definition, the tomato is clearly a vegetable — almost always served in savory dishes, and never as a dessert. When eaten fresh and raw — either solitary or as part of a salad — we typically sprinkle on salt, not sugar. So if we ask “Is the tomato a fruit or a vegetable?” then the best answer is “a vegetable”.

To recap our initial questions and answers:

1) Is the tomato a fruit? Yes, it is.

2) Is the tomato a fruit or a vegetable? It’s a vegetable.

It all depends on the definition of the word “fruit”. These two questions have subtly different wordings that imply two different definitions for the word, resulting in two different answers that appear to be contradictory. But in fact these two answers are not contradictory, because we are using the word “fruit” in two different ways.

The upshot of this story is twofold:

1) Some hotly debated questions can be answered by simply defining the terms used in the question.

2) A single word can have multiple definitions, and these different meanings often correspond to distinct domains. If the most appropriate domain can be identified, then the best definition will often follow.

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