There are varying degrees of scepticism. Some may doubt whether we can have knowledge in a specific area, such as ethics or history. Some may entertain doubts concerning each of their beliefs, wondering which are true and which false. Others may entertain doubts concerning all of their beliefs, wondering whether all of them might be false.

Gilbert Ryle’s response to scepticism is a response to it in this last form. Ryle argues that though we may have doubts concerning each of our experiences, we cannot have doubts concerning all of them. Though we may not be able to identify which of our experiences accurately represent the world, we can be certain that at least some of them do.

Ryle draws an analogy between misleading experiences and counterfeit coins. He writes:

“In a country where there is a coinage, false coins can be manufactured and passed… An ordinary citizen… might become suspicious of the genuineness of any particular coin that he received. But however general his suspicions might be, there remains one proposition which he cannot entertain… that all coins are counterfeits. For there must be an answer to the question ‘Counterfeits of what?’” [Gilbert Ryle, Dilemmas, pp94-95].

Ryle’s argument, then, is that in order to have counterfeit coins there must be at least some genuine coins of which they are counterfeits. It makes no sense to talk of counterfeits if all coins are counterfeits; therefore, if there are counterfeits, then there are real coins too.

This point, Ryle’s argument suggests, applies to our experiences too. If there are misleading experiences, experiences that do not represent the world accurately, then there must also be at least experiences that do represent the world accurately. Although we can say of each of our experiences that it may be misleading, we cannot say that of all of them, for the notion of a ‘false’ experience is parasitic upon that of a ‘true’ one.

Consider the following situation. The Royal Mint designs a new set of coins. The national press ensure that these designs are well circulated, and a date is given for the release of the coins into public circulation. Across the country, a large number of counterfeiters make their preparations. They manufacture vast quantities of counterfeit coins, and when the announced date arrives they head off to their local shopping centres and spend freely. In the meantime the Royal Mint has made another decision, one that has not become common knowledge, the decision that no new coins are to be made. The counterfeiters can still successful use their illegal tender. A shop-keeper aware that there are counterfeiters in the world can wonder of each coin that he receives whether or not it is ‘real’. Yet, contrary to Ryle’s claim, every coin is a counterfeit.

So what has gone wrong? Well, the problem with Ryle’s story is that the notion of a ‘false’ coin need not be parasitic upon an actual ‘real’ coin. The mere notion of a real coin will suffice. This gives us an answer to the “Counterfeits of what?” question without committing ourselves to the claim that there really is such a coin in circulation.

Similarly, as long as we have an idea of what a ‘real’ experience would be, we can coherently say “All of my experiences may be dream-experiences”. And we may, for all Ryle says, be right.