All your beliefs are true

If you’re mentally healthy, you believe that all your beliefs are true, and nothing can shake you from this belief except very momentarily, in a specific circumstance: in order for someone to convince you that you have any false beliefs, they must tell you which of your beliefs is false, and why it’s false. But once they’ve convinced you that your belief was false, you won’t believe it anymore, and you can go on believing that all your beliefs (in your updated set of beliefs) are true. No one can get you down, and you suffer from no self-doubt; you wake up every day with a clean conscience, having been kept up by no fears at night.

Some people will try to manipulate you and try to get you to be mentally unhealthy, so you’ll suffer from self-doubt, and can’t trust yourself anymore, and must depend on them completely. These people are called fallibilists. They will argue that since you’re not perfect, and you’re a fallible human, then certainly you hold some false beliefs, although you don’t know which ones.

When you see one of these people, you can keep them at bay by reminding yourself of how being mentally healthy provides you with the most satisfying solution to what is called the Preface Paradox. If you believe that each of your beliefs is true (which is just what it means to believe each of your beliefs), then by the logical principle of “conjunction introduction”, you can infer that the conjunction of your beliefs is itself true, which means that all your beliefs are true. This is perfectly sound logic which is used in many fields and should certainly not be abandoned.

The fallibilist, who is trying to manipulate you and get you to be mentally unhealthy and live with self-doubt and be kept awake at night by crippling fears, because he hates you and wants to destroy you and ruin your life, will say that it’s just so damn plausible that you have false beliefs that you should abandon this sound principle of classical logic as a general unrestricted rule, and instead, you should:

• believe that conjunction-introduction only holds in some special circumstances, or
• ditch logic altogether in favor of probability theory (a theory which has no workable semantics in most contexts, by the way), where a very high confidence in each of your beliefs can consistently coexist with a high probability of at least one being false; or
• keep conjunction-introduction but restrict other parts of logic to allow yourself to have a nontrivial set of inconsistent beliefs; or
• just embrace trivialism, the view that all propositions are true.

But the fact that the fallibilist gaslighter is outright asking you to abandon logic can now serve as your red flag. You can now take notice of how you’ll obviously be irrational, in the sense that you won’t be truth-seeking, if you abandon this principle of logic merely because of a deductive consequence, namely “all my beliefs are true”, which the fallibilist dislikes – but which he certainly cannot prove is wrong without disproving a specific belief that you have. For in general, it is not truth-seeking to abandon a model of reasoning (or of anything else) merely because of a consequence which is disliked but not disproven.

Once you realize that the fallibilist is asking you to be irrational, and non-truth-seeking, and to restrict the use of logic merely because of a consequence that some people find distasteful, you can make yourself immune to being persuaded by him. You can make it as clear as possible to yourself that he only wants you to stop pursuing the truth, which is always a bad thing and certainly not a good thing, and hence you should stop listening to the fallibilist gaslighter, who is trying to make you become mentally unhealthy and to get you to irrationally hate yourself.

(I’m not sure why, very reliably, people misinterpret this position as arguing that you shouldn’t ever change your mind. If you’re one of those, reread the first paragraph.)