I get your point FF but with all due respect technical charting can be seen to have science within it.
There is the mathematics, patterns, probability and the psychology of the market which is made up of traders / humans.
It does get harder and more blurred these days with the ever increasing use of algo / bot / quant trading.... mathematics again though.
No doubt there is an art and interpretation by a Chartist and nothing in life is certain other than death and taxes (maybe not taxes if you live in a tax haven though haha) that was mentioned earlier today.
Charts are essentially a visual representation of historical trading activities which can be aligned to events or other influencing factors like Ann's, rumours, shorts, tweets etc.
It can provide a snapshot of how the market (humans mostly) reacted on those given events and being creatures of habit there is a probability, not guarantee, of how they could react to similar future events or even price points like going from pips to 5c increments once a stock breaks 10c.
You can visualise certain volume areas where resistance and support zones may be seen potentially in the future.
There are various methods or styles and indicators, oscillators etc all based primarily around outcomes from math calculations, OHLC on a bar, volume Inc / Dec, averages etc.
There is actually a lot of work trying to learn and understand a chart.
Bulkowski site is great for real world statistics of how certain patterns / candles play in a % sense gathered over years of data.
ThePatternSite.com is internationally known author and trader Thomas Bulkowski's FREE website for research on chart patterns, candlesticks, and much more!
thepatternsite.com
Richard Wyckoff, one the earliest technical analysts if you like observed many things and off ticker tapes back then.
StockCharts.com's comprehensive collection of Financial Analysis articles and explanations
school.stockcharts.com