“There is no truth.”
This is an assertion made by people who never live up to it. They will always state something – many things in fact – that contradict the premise that there is no such thing as truth. That is, they will make statements that they deem truthful. Everyone makes assertions as if they are truth. In fact, the meaning of assertion is: a confident and forceful statement of fact, or belief. (Synonyms for assertion: declaration, claim, opinion, affirmation, insistence.)
Truth exists – it usually falls into two categories: Subjective (personal) and Objective (universal).
This most often comes down to personal beliefs which do not require proof but are based on faith, or personal experience. However, there are subjective truths based on fact. This would involve the experience of something that happened but no one outside of the parties involved was there to witness it, or no one else accepts what happened because of their own beliefs. For example, a victim of domestic violence that could not prove that s/he was a victim of said violence, especially when those who know the perpetrator do not believe that s/he is capable of said violence. Their lack of belief does not negate the truth of the experience.
This is based on what IS, that has nothing to do with what people believe, their emotions, or perceptions: for example, the Sun is necessary for life on the planet; one plus one equals two; people need air, water and food to survive.
New Age Nonsense
Most die-hard New Agers believe that truth does not exist because everything is an illusion, your senses cannot be trusted, or something along those lines.
What is truly disturbing, is the number of New Agers who peddle this belief but then go on to teach, give advice, write books etc., as truth. If someone is going to tell people what to do they need to make assertions based on some type of truth. Why would anyone waste their time and money on fraudulent advice? So, the people making a living out of their own beliefs, practices, experiences and so on, must believe them to be true in the first instance otherwise they are outright charlatans. If they do not believe their own beliefs, they have no business (pun intended) selling them to other people.
Anyone who claims that there is no truth needs to take a life-long vow of non-communication in order to remain true to this assertion. If not, then every time they make a statement, they are contradicting their own ‘philosophy’.