Your mental life involves a lot of different kinds of thoughts. You can make decisions about what to do, or figure out some truths about the world, or just daydream in a vivid series of images. There’s great diversity to the types of thoughts you can think.

即便如此，我们倾向于认为你一次只能有一个想法。你可以在不同的想法之间快速切换，或者你可以一个接一个地想很多想法，但你不能同时想一个以上的想法。

这是一个错误。有一种方法可以同时考虑两个想法。这不是一个专门的、专注的专家思考者会做的事情;我们都经常这样做。我会解释。

First, we must distinguish between mental actions and passive thoughts.

Sometimes you don’t direct your thought at all; your thoughts are just led, outside your control. This happens in mind-wandering, or when something you forgot suddenly comes to mind, or when you’re haunted by images that won’t go away.

(For more on mind-wandering, check out Zach Irving’s work, likethis paper. For a careful discussion of the difference between mind-wandering and active daydreaming, check outthis paperby Fabian Dorsch.)

But sometimes you do direct your mind; you cando在思想的东西。你在思想中做的事情是精神行为。You canremember your tenth birthday, oradd 57 and 18, orimagine a blue horsein mental action.

Thinking two thoughts at once is possible when you engage in mental action that isintentional.

It’s a difficult philosophical question exactly how to define intentional action, but the concept of intentional action is not a technical term. We talk about intentional action all the time. Whether something is doneintentionallymatters to how we attribute actions to people, and to whether we praise or blame them for doing what they did.

Fortunately, we don’t have to worry about defining intentional action here. We can just rely on a couple of important facts about intentional action.

First: when you do something intentionally, you have in mind an idea of the thing you’re trying to do. For example, when you intentionally kick a ball to a friend, you think ofkicking the ball to a friend. That’s your intention. The same point applies in mental action: when you intentionallyrecall your tenth birthday, you have in mind that you’rerecalling your tenth birthday.

Second: when you do somethingin order todo something else, you can do several things all at once. Here’s an example from the influential late philosopher Donald Davidson. If you flip the light switchin order toturn on the lights—and the switch works, so that’s all you have to do to turn on the lights—then you have both (1) flipped the switch and (2) turned on the lights, and you’ve done both intentionally.

如果我们将这两种关于有意行为的观察结果结合起来，并将其应用到心理行为中，我们就会看到在心理行为中你是如何同时想到两种想法的。

When you intentionally do somethingin order todo something else as well, you still have in mind an idea of what you’re doing. Now it’s just a more complicated idea. In the Davidson example from above, if you intentionally flip the switchin order toturn on the lights, you have in mindflipping the switch, and you have in mindturning on the lights, and you have in mind the connection between the two: you think of doing the first thing as a way of doing the second thing.

Consider the same kind of case in mental action. If you’re J.K. Rowling writing the Harry Potter books, you can intentionallythink of an insultin order tothink of something Malfoy could say to Harry. If you carry out that (simple enough) task successfully, you can perform two mental actions at once: you (1) think of an insult and (2) think of something Malfoy could say to Harry. You can do them both at the same time because you arealready thinking of你能想到的马尔福会对哈利说的任何侮辱的话。在这种情况下，如果你认为“马尔福会对哈利说这句话!”这是一种侮辱，那你就没有什么可做的了!

Here’s a more mundane example. At a store, you could intentionally figure out which of two soap brands is cheaper in order to decide which soap to buy. In performing this mental task successfully, you can think “Soap A is cheaper” at the same time that you decide “I’ll buy Soap A.” You can do both at once since you already committed, at the outset, to buying the cheaper soap.

These complex intentional mental actions are ubiquitous. We perform them whenever we intentionally perform a mental action ofonekind in order to perform a mental action ofanotherkind as well. It doesn’t take extra effort, necessarily, and it doesn’t involve any fancy mental acrobatics that are only available to expert thinkers.

We should give up the misconception that all our thought is serial. You can think two thoughts at once. You already know how to do it, and you do it all the time.