Why nothing can be known with certainty, and why it is reasonable to say that we know things

What if anything can we know about reality? What if anything should we assume without being able to know it? Why is it reasonable to assume that reality is broadly as it seems to be? Why is it reasonable to say that we know things? I wrote an earlier version of this some years ago, and I am now thinking it through again. Please let me know what you think.

Summary

1. Speaking strictly philosophically, nothing can be known with certainty

1. I seem to interpret the universe, and make assumptions, using my thinking.
2. But I can never know if any of my interpretations or assumptions are correct.
3. It is possible that this assumption may itself be incorrect.
4. However, that possibility does not prove that anything can be known.

2. There is a scale of at least five possible theories of reality

1. All that seems to exist, even what seem to be thoughts, may be an illusion.
2. Only what seem to be thoughts exist independently.
3. Only one thinking being and its thoughts exist.
4. Several thinking beings and their thoughts exist.
5. Real physical objects also exist, in conjunction with any of these scenarios.

3. In ordinary day-to-day life, it is reasonable to assume that reality is broadly as it seems to be

1. Each new scenario seems closer to the evidence of my experience.
2. Each assumes the existence of extra things that cannot be known to exist.
3. Each seems increasingly functional as a working assumption of reality.
4. These apparent patterns contain a key ‘on/off’ reason-switch.
5. This leads me to assume that reality is broadly as it seems to be.

4. In ordinary day-to-day language, it is reasonable to say that we know things

1. When we say we know things, this includes several unspoken conditions
2. We should apply these unspoken conditions consistently

1. Speaking strictly philosophically, nothing can be known with certainty

1.1. I seem to interpret the universe, and make assumptions, using my thinking.

The universe is all that exists, whether thoughts or things. Some of these:

• I am aware of experiencing (conscious thoughts, my house, eating ice cream)
• I experience but am not aware of (subconscious thoughts, my 42nd eyelash)
• I am aware of but do not experience (composing an opera, visiting the moon)
• I neither experience nor am aware of (thoughts I have not had, specific aliens)

These entities seem to change, combine and interact in complex ways. I must therefore interpret my awareness of them, then make assumptions based on my interpretations. I call the mechanism with which I do this, ‘my thinking’.

1.2. But I can never know if any of my interpretations or assumptions are correct.

Why? Because I can only interpret their correctness by using the very mechanism whose ‘efficiency-in-being-correct’ that I am testing (i.e. ‘my thinking’).

• If I assume that my thinking always produces correct interpretations, then this assumption may itself be an incorrect interpretation, caused by flaws in my thinking about which I am unaware.
• If I doubt my thinking’s reliability in always producing correct interpretations, then I must also doubt its reliability in testing the correctness of those interpretations.

1.3. It is possible that this assumption may itself be incorrect.

• It may be that something can be known, using mechanisms other than ‘my thinking’, and that ‘I’ am simply not yet aware of how this can be done.
• If I am shown a proof that ‘something can be known’, then I will change this assumption.

1.4. However, that possibility does not prove that anything can be known.

• To prove that ‘something can be known’, it is not sufficient to undermine the certainty of this or any theory of why ‘nothing can be known’.
• Indeed, undermining the certainty of this assumption can reinforce it, unless the undermining is accompanied by a positive alternative proof.
• To prove that ‘something can be known’, the onus is on the ‘knowledge-claimer’ to show how this can be done, using a proof that does not rely on the very thinking that is itself being tested.
• Until this happens, this seems the safest and purest working assumption to make about the nature of the universe: that, based on what seems to be my experience so far of the universe, nothing can be known.

2. There is a scale of at least five possible theories of reality

2.1. All that seems to exist, even what seem to be thoughts, may be an illusion.

Overview: This is the most cautious assumption of reality. Thoughts seem the most certain entities to exist, but maybe they only seem to be thoughts. Maybe they are something else that ‘I’ do not have access to any information about. Maybe nothing actually exists beyond the illusion of what seems to exist.

• Experience: This scenario seems the furthest away from the apparent evidence of ‘my experience’, to the extent of seeming incompatible with ‘my experience’.
• Reason: This seems to involve a paradox. However, ‘I’ cannot rationally rule it out as I have no way of disproving it or of proving any alternative. Maybe this scenario is correct, but what seems to be ‘my thinking’ cannot comprehend how. This is the easiest scenario to defend using reason alone, because it makes no definitive challengeable assertion.
• Functionality: As a working assumption of reality, this enables the illusory ‘me’ to function in what seems to be the same way as the real ‘me’ would if everything did exist. The illusory ‘me’ is at no disadvantage by virtue of being an illusion, because what seems to be ‘everything else’ is also an illusion.

2.2. Only what seem to be thoughts exist independently. 

Overview: If this is correct, then the illusion of ‘me’ is simply part of ‘the thoughts.’ This illusory ‘me’ cannot understand how this technically works, but this may be because ‘understanding how this works’ is not part of the ‘the thoughts.’

• Experience: Assuming the actual existence of something (in this case, the ‘independent thoughts’) this scenario seems the furthest away from the apparent evidence of my experience. What ‘I’ seem to experience is an illusion, and so is ‘me’. What ‘you’ may seem to experience is an illusion, and so is ‘you’.
• Reason: Of the scenarios that make a challengeable assertion (by assuming the actual existence of something), this seems the easiest to defend using reason alone. This is because it involves the fewest entities that are “assumed to exist without knowing that they exist,” i.e. the ‘independent thoughts’. This means there are fewest points of attack where the ‘independent thoughts’ (or indeed the illusory ‘me’ or ‘you’) are obliged to prove anything.
• Functionality: As a working assumption of reality, this scenario renders meaningless any attempts to analyse or choose or do anything. The ‘independent thoughts’ are, in effect, in control. Whatever the illusory ‘me’ or ‘you’ seems to decide, the ‘independent thoughts’ just continue to do whatever they would have been doing anyway.

2.3. Only one thinking being and its thoughts exist. 

Overview: If this is correct, there are three sub-possibilities.

• Only I, Michael Nugent, exist. My thinking has generated the illusions of me having written this paragraph, and of ‘you’ existing and reading this. An analogy is that Michael Nugent is a computer programmer, and ‘you’ are some lines of code in a computer programme that he has written.
• Only you, the person who seems to be reading this paragraph, exist. Your thinking has generated the illusions of ‘Michael Nugent’ existing and writing this paragraph, and of you reading this. An analogy for this relationship is that you are a computer programmer, and ‘Michael Nugent’ is some lines of code in a computer programme that you have written.
• Only another thinking being exist. Its thinking has generated the illusions of ‘Michael Nugent’ existing and writing this paragraph, and of ‘you’ existing and reading this. An analogy is that the ‘thinking being’ is a computer programmer, and ‘Michael Nugent’ and ‘you’ are some lines of code in a computer programme that it has written.

The sole ‘thinking being’ (whichever one of ‘us’ it may be) has also generated the illusion of all of the world’s literature, history, art, sport, civilisations, wars, knowledge, pleasure, pain and ongoing events. This being is what some people (if they existed) might call a god. That said, if you are the sole ‘thinking being’, you might consider generating a higher standard of illusory life for yourself.

• Experience: Because some ‘thinking being’ is assumed to exist, this scenario seems another step closer to the apparent evidence of ‘my experience’.
• Reason: It also seems another step harder to defend using reason alone. Another entity (you or me or another ‘thinking being’) is assumed to exist that cannot be known to exist, i.e. its existence cannot be proved using reason alone.
• Functionality: As a working assumption of reality, this may considerably boost the self-esteem of whichever ‘thinking being’ is assumed to exist. It also renders meaningless any attempts to debate or communicate anything, because nobody exists to communicate with. The thinker’s apparent disagreements with ‘other people’ are really internal arguments between the thinker’s own thoughts.

2.4. Several thinking beings and their thoughts exist.

Overview: You and I and others exist as ‘thinking beings’. We generate the illusion of sensory experiences, using our thinking, and we interact telepathically in a universe with no physical entities. However, there are limits to what our thinking can do. For example, each of us still seems to cease to exist (or ‘die’) at some stage, and we only seem able to communicate some thoughts and not others. We do not know why we all generate (more or less) the same illusions of sensory experiences, but this may be simply the way things happened to pan out.

• Experience: Because the ‘thinking beings’ can communicate with each other, this scenario seems another step closer to the apparent evidence of ‘my experience’.
• Reason: It also seems another step harder to defend using reason alone. Many entities (the interacting ‘thinking beings’) are assumed to exist that cannot be known to exist, i.e. their existence cannot be proved using reason alone.
• Functionality: As a working assumption of reality, this enables me to function and interact with others, in what seems to be the same way as I would if our bodies and other objects actually existed. For example, we only seem able to transmit some thoughts and not others, and these ‘transmittable thoughts’ seem to correspond to those that we would communicate through our senses, if our senses existed.

2.5. Real physical objects also exist, in conjunction with any of these scenarios.

Overview: Adding real physical entities to any of the above scenarios, such as atoms and rocks and trees and human bodies and bicycles and microwave ovens and space rockets and planets and galaxies.

• Experience: Adding real physical entities to any scenario brings it another step closer to the apparent evidence of ‘my experience’. The effect is greatest with scenario four, which combines thinking beings, their thoughts, and interaction between the thinking beings. Here, adding real physical entities makes the nature of reality identical to the apparent evidence of ‘my experience’.
• Reason: Adding real physical entities also makes each scenario another step harder to defend using reason alone, by assuming extra entities that cannot be known to exist.
• Functionality: As a working assumption of reality, the real or illusory ‘me’ can function (in each scenario) in much the same way irrespective of whether the physical objects are real or illusory. This is because, in each scenario, my real interaction with real physical objects seems functionally identical to ‘my’ illusory interactions with illusory physical objects.

3. In ordinary day-to-day life, it is reasonable to assume that reality is broadly as it seems to be

3.1. Each new scenario seems closer to the evidence of my experience.

This is the first of three patterns that these possible scenarios seem to follow.

• In the first scenario, all that seems to exist, even what seem to be thoughts, may be an illusion. This scenario seems so far away from the apparent evidence of ‘my experience’ as to be incompatible with it.
• Gradually extra entities are assumed to exist (‘thoughts’, ‘thinking beings’, physical objects). Each of these seems to match with parts of the apparent evidence of ‘my experience’.
• In the final scenario, all permutations of thoughts are combined with real physical objects. This makes the nature of reality identical to the apparent evidence of ‘my experience’.

3.2. Each new scenario assumes the existence of extra things that cannot be known to exist

This is the second of three patterns that these possible scenarios seem to follow.

• In the first scenario, all that seems to exist, even what seem to be thoughts, may an illusion. This is the easiest to defend using reason alone, because it makes no definitive challengeable assertion.
• Gradually extra entities are assumed to exist (‘thoughts’, ‘thinking beings’, physical objects) that cannot be known to exist. Each of these assumptions makes each scenario a step harder to defend using reason alone.
• The final scenario has the greatest number of ‘entities that are assumed to exist but cannot be known to exist.’ This makes it the hardest scenario to defend using reason alone.

3.3. Each new scenario seems increasingly functional as a working assumption of reality

This is the third of three patterns that these possible scenarios seem to follow.

This third pattern depends on something being assumed to exist. If everything is an illusion, then the illusory ‘me’ is at no disadvantage by virtue of being an illusion, because what seems to be ‘everything else’ is also an illusion.

• Stage one: ‘independent thoughts’ or another ‘thinking being’ are assumed to exist, but ‘I’ am not. This renders meaningless any attempts by the illusory ‘me’ to analyse or choose or do anything.
• Stage two: I am assumed to exist, as the sole ‘thinking being’. I can now seek to analyse and choose and do things, but cannot communicate as nobody else exists.
• Stage three: I and other ‘thinking beings’ are assumed to exist. I can now function in much the way that I seem to, based on the apparent evidence of ‘my experience’. This allows me to have a meaningful working assumption of reality.

At any of these three stages, the real or illusory ‘me’ can function in much the same way irrespective of whether the physical objects are real or illusory. This is because, at each stage, my real interaction with real physical objects seems functionally identical to ‘my’ illusory interactions with illusory physical objects.

3.4. These apparent patterns contain a key ‘on/off’ reason-switch

In terms of making a working assumption about the nature of reality, the biggest conflict is not whether physical objects or gods are assumed to exist. It is whether anything is assumed to exist that cannot be known to exist, using reason alone.

In other words, the switch is turned to ‘on’ once it is assumed that anything at all exists. This may not even be ‘thoughts’; it may be something that seems to be ‘thoughts’ but is actually something else. But as long as it is assumed that that something exists, and it cannot be known to exist, the switch has been turned to ‘on’.

If it is assumed that it is self-evident that something must exist, then the switch is turned to on once something identifiable is assumed to exist that cannot be known to exist. Depending on the rational faculties of the ‘assumer’, this could be when ‘thoughts’, a ‘thinking being’ or ‘me’ is assumed to exist.

3.5. This leads me to assume that reality is broadly as it seems to be

Once ‘I’ turn on this switch, ‘I’ have assumed in principle that “things-that-cannot-be-known-to-exist” may exist. What then might I assume these things to be, based on experience, reason and functionality?

Experience and Reason

• Once I assume that anything exists, it is now rational to assume that reality consists of those things which seem to be (a) more consistent than other possibilities with the apparent evidence of my experience, and (b) more likely to be the case than other possibilities, based on applying reason to the apparent evidence of my experience.
• This leads me towards assuming the final scenario of my five theories of reality: that reality includes me as a thinking entity, you and other thinking entities, thoughts that are generated by me and you and other thinking entities, and real physical objects, whether animate or inanimate. It is not rational to assume that some, but not all, of these types of things exist.
• Also, it is not rational to assume that any specific types of things exist if they are either (a) less consistent than other possibilities with the apparent evidence of my experience, or (b) less likely to be the case than other possibilities, based on applying reason to the apparent evidence of my senses. This includes unicorns, leprechauns and gods.

Functionality

• This argument is strengthened if it results in a working assumption that makes it easier for ‘me’ to function in what seems to be reality. This also leads towards the final scenario of my five theories of reality, where ‘I’ am assumed to exist and interact with other thinking beings and physical objects.
• It does not matter if ‘I’ am wrong in this assumption. If so, ‘I’ will just seem to cause the same things to happen as would happen anyway.
• So, for practical reasons as well as theoretical ones, my working assumption is that reality is broadly as it seems to be, based on applying reason to the apparent evidence of my experience, while remaining open to changing my specific beliefs if I become aware of new evidence.

Note that I am assuming that reality is broadly as it seems to be, not that every detail of reality is actually as it seems to be. The details of reality can be different to what we seem to experience, and indeed can be counterintuitive to what we seem to experience. Specifically, I am saying that:

• It is reasonable to assume that we exist as physical, sentient, thinking beings in a world of actual physical objects.
• It is reasonable to assume that the specifics of reality are described by those theories that seem most likely after applying reason to the apparent evidence of our experience.
• It is reasonable to always be prepared to change our assumptions if we get new evidence, but it is not reasonable to change our assumptions before that.
• When we build on those assumptions, the most reliable way to devise effective theories about our shared reality is to use the scientific method. This enables us to develop models of reality that are consistent with what we are gradually learning about the laws of nature.
• For example, what seems to be solid matter (based on the apparent evidence of our direct experience) turns out to be  composed ultimately of subatomic particles and empty space with energy fluctuations (based on applying reason and the scientific method to the apparent evidence of our direct experience).

4. In ordinary day-to-day language, it is reasonable to say that we know things

4.1. When we say we know things, this includes several unspoken conditions

• Based on assuming that we exist as thinking beings…
• Based on assuming that the physical world exists…
• Based on what we seem to directly experience…
• Based on the currently best available evidence…
• Based on applying reason to that evidence…
• Based on forming beliefs most proportionate to the evidence…
• Based on the outcomes of scientific experiments…
• Based on reaching conclusions beyond reasonable doubt…
• Based on accepting that we may be mistaken…
• Based on being open to the possibility of new evidence…

… we can reasonably say that we know something to be the case.

4.2. We should apply these unspoken conditions consistently

If we are talking about knowing whether or not God exists, we should not skip during the same conversation between strictly philosophical language and ordinary day-to-day language.

In any given conversation, we should use either the standard of proof that we cannot know anything for certain, or else a standard of proof based on something like the unspoken conditions described above. But whatever standard we are using, we should apply that consistently to all assertions made as part of that conversation.

As a final caveat, it may be the case that we are not in control of what we are thinking or saying. It may be the case that our thoughts and actions are deterministically generated, and that free will is an illusion. If that is the case, it does not effect what is written here, as we will just do whatever we end up doing anyway.