- First principles are true
- First principles are necessarily true
- First principles are indemonstrable – they are not and cannot be deduced from anything else since otherwise the premises from which they are derived would be prior and not the First Principles themselves.
- First principles are more certain than anything derived from them – anything derived (deduced) from them can contain errors but first principles are free from any possible error as necessary truths.
In every systematic inquiry (methodos) where there are first principles, or causes, or elements, knowledge and science result from acquiring knowledge of these; for we think we know something just in case we acquire knowledge of the primary causes, the primary first principles, all the way to the elements. It is clear, then, that in the science of nature as elsewhere, we should try first to determine questions about the first principles. The naturally proper direction of our road is from things better known and clearer to us, to things that are clearer and better known by nature; for the things known to us are not the same as the things known unconditionally (haplôs). Hence it is necessary for us to progress, following this procedure, from the things that are less clear by nature, but clearer to us, towards things that are clearer and better known by nature. ( Aristotle, Physics. 184a10–21)
Finding Purpose List of First Principles