1) Academic 2) Conceptual thinker 3) Creative thinker 4) Dreamer 5) Einstein, famously 6) Idealogue 7) Impractical person 8) Intellect 9) Intellectual 10) Logician 11) Philosophical speculator 12) Someone who theorizes 13) Theoretician 14) Theoriser 15) Theorizer 16) Thinker 17) Thinking person 18) Truth-seeker 1) Muser 2) Philosopher 3) Theoriser 4) Theorizer 
• (n.) One who forms theories; one given to theory and speculation; a speculatist.
The'o·rist noun [ Confer French théoriste .] One who forms theories; one given to theory and speculation; a speculatist. Cowper. « The greatest theoretists have given the preference to such a government as that which obtains in this kingdom.» Addison. 
[n] - someone who theorizes (especially in science or art)
theoretician, theorist 1. A person who theorizes, especially one who specializes in the theory of some art, science, etc.2. One who formulates, studies, or is an expert in the theory of a science or an art.
theoretician noun someone who theorizes (especially in science or art)