think you’re on better footing when you examine your beliefs about the present. You can be vague about the past. It can be shrouded in the mists of time. But the present stares you in the face.
What are the distinctive sources for your beliefs about the present? Well, hmm. Gee, when you think about it, it seems that most of your beliefs about the present moment, about things going on beyond the purview of your own immediate perception, are based on the testimony of other people and your memory of what they’ve said. That’s how you know about current events around the world: testimony and memory. And you have just seen the wall you run into when you try to produce even a single shred of untainted evidence that either memory or testimony is ever reliable.
But this can get much more immediate. Even the testimony you remember comes initially through the medium of your own original sense experience. And many things that you know about the more immediate present, you know just from your current experience. This is how I know there is a blue cup on my desk and a steel watch with a black strap on my wrist. I see them. Perhaps sense experience can give the direct, provable tie to reality that the skeptic seems to be seeking. But, of course, the skeptic has challenging questions about sense experience as well.
Sense experience
You don’t need the testimony of others to tell you what’s going on in your room or other immediate physical space right now. And I’m the same. I know by sight that my computer monitor is on. I know by sight and touch that the keyboard is working. I can smell the delightful aftershave I just splashed on. I can hear the hum of my printer. And you have your own direct experience of yourself and your environment. A great number of present moment beliefs are just rooted in the immediacy of sense experience. In the first century BCE, the philosopher and poet Lucretius asked: “What can give us surer knowledge than our senses? With what else can we better distinguish the true and the false?” Our functioning senses and the sense experiences they yield provide our most basic ways of gathering any information about the world around us.
The skeptic, of course, wants to ask, “How do we know that sense experience is ever reliable?” You could see that one coming a mile away, at least if you can trust your own inferences. And what is the answer to the skeptic here? You may be tempted to say, “Look, I recall many times in the past seeming to see something, like a penny on the street, and when I got closer, there it was, just as it had appeared to be. So sense experience is sometimes reliable.”
This is almost embarrassing. First, if you think or say this, you are simply making use of your memory of a past experience. But, as you see in the preceding section on memory, nobody can come up with any good evidence that memory is ever reliable. Forget that for a moment, though, for the sake of argument. The little sample story suggested for you in the previous paragraph just recounted a memory of one initial sense experience that was later confirmed by what exactly? Another memory of another sense experience! So you confront the bane of circular reasoning again. If all sense experience has been called into question by the skeptic, it’s not sufficient for you to answer the challenge by appealing to a particular piece of sense experience, all of which is in question, and especially using memory, which has also been called into question.
Things are looking bad, so to speak. But that appearance might itself be deceiving, so hang in there. If you continue to read on in the coming paragraphs of this chapter, I promise that things are going to seem to get much worse for a few minutes, and then you’ll be truly amazed at what happens. Astonished. Shocked. You’re skeptical? Trust me. Aren’t you almost afraid to peek at beliefs about the future?
Here’s a relief. You don’t even have to go to any particular trouble to consider the reliability of distinctive beliefs about the future, because the same reasoning applies. You form such beliefs based on the past and present. And since you are realizing now that you can’t come up with any good reason for trusting the sources for your beliefs about the past and present, that just transfers over to an equal lack of justification for trusting any beliefs you have about the future. I leave it to you to think this through thoroughly, at some time in the future. Even Demosthenes saw in his ancient time that, “No man can tell what the future may bring forth.”
Conclusions about source skepticism
Notice that the skeptic’s questions don’t just show that you can’t absolutely prove the reliability of your sources for beliefs about the past, present, and future. The point is much deeper. You can’t even provide one single, pure piece of evidence for this assumption you share with everyone else, and on which the credibility of all your other particular beliefs depends: The sources of our beliefs are sometimes reliable.
And this fact is certainly surprising and perplexing, if not deeply troubling. Where is your anchor to reality? What ties your belief-forming mechanisms to the way things really are? The skeptic has questions. And there seem to be no good answers. But, of course, as is often the case in philosophy and life, it gets worse before it gets better. Or, it becomes at least crazier and more interesting. To find out, look at the next section, which covers a whole different type of skeptical questioning, as we go from the frying pan into the fire.
The questions of radical skepticism
The questions of source skepticism in the previous few sections direct your attention to the reliability of the most basic belief-forming mechanisms, or sources for your beliefs. It asks: How do you know that memory, testimony, sense experience, or any other possible sources of your beliefs are ever reliable guides to realities outside yourself? Radical skepticism proceeds differently. It suggests a radical hypothesis or scenario incompatible with a huge array of your typical beliefs, a hypothesis so opposed to what you ordinarily assume that, if it were true, an enormous number of beliefs that you now have would be false. The radical skeptic points out that continuing to hold your normal beliefs requires denying this radical hypothesis and believing its wild alternative scenario to be false. So you seem already committed to its being false. But then, the radical skeptic typically asks how you know or have any evidence to believe that it is false.
Radical skepticism about the past
The 20th-century philosopher Bertrand Russell once posed a radical hypothesis concerning the past that is called “The Five-Minute Hypothesis.” You have beliefs about breakfast this morning, about how you slept last night, about what time you went to bed, about your activities last evening, as well as about what transpired throughout the entire day. You have beliefs about the day before yesterday, and the day before that. Your memory reaches back to last week, and last month, and last year. You have a wealth of beliefs about things that happened decades in the past, perhaps tens of thousands, or even millions of such beliefs. But consider this hypothesis:
The Five-Minute Hypothesis: The entire universe sprang into existence from nothing five minutes ago, exactly as it then was, apparent fossils in the ground, wrinkles on people’s faces, and other signs of age all instantly formed and thoroughly deceptive.
This hypothesis is incompatible with all your beliefs concerning anything you think happened more than five minutes ago. If it is true, all those past-oriented beliefs of yours are false. And the same for me. I have no natural parents, no natural children, I am not really married, I have never signed a contract of any kind, and so on. I never got a philosophy degree. Plato never existed. I have false memories about all these things, memories that sprang into existence along with me and you five minutes ago, or a little longer ago, since you’ve been reading and thinking about it all for a bit now. But nothing existed before that cosmic appearance act roughly five minutes past. Weird. Bizarre. Crazy.
You might object right away, “But how do you know the Five-Minute Hypothesis is true?” If you react like this, your response is natural.
